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Papers by mechai abdelbasset

In the present work, 108 strains of lactic acid bacteria (LAB) were isolated from Algerian tradit... more In the present work, 108 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fermented milk (Jben, Klila, Raib and Lben) in order to evaluated their enzymatic activities (Proteolytic, caseinolytic, lipolytic, and α-amylase, activities) and their antimicrobial activity relative to different reference strains. Only 12 strains were retained, they were characterised in respect to their functional properties. The retained strains were identified phenotypically and analyses of the 16S rDNA gene as; Lactococcus lactis subsp lactis (3 strains), L. lactis subsp. cremoris (1 strain), L. lactis subsp. lactis biovar. diacetylactis (2 strains), Lactobacillus plantarum (3 strains), Lactobacillus casei subsp. casei (2 strain) and Leuconostoc mesenteroides (1 strain). Lactococcus strains were those that showed the greatest degree of acidifying and proteolytic activity, however the highest level of caseinolytic activity was shown by the CFE of tow strains of Lactobacillus c...

Asian Journal of Microbiology Biotechnology and Environmental Sciences, Apr 8, 2014

African Journal of Biotechnology, Aug 18, 2008

Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from indivi... more Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from individual household. They were evaluated for the presence of autochthonous bacteriocin-producing lactic acid bacteria. From 13 of these samples 52 strains of lactic acid bacteria were isolated, and shown to exhibit inhibitory activity against the indicator strain Listeria monocytogenes. Five of these inhibitor-producing isolates were selected for further study on the basis of their relatively wide antimicrobial spectrum. The inhibitory spectra of activity of the selected strains were evaluated against a range of Gram-positive and Gram-negative test organisms. Listeria monocytogenes and Staphylococcus aureus were the most sensitive indicator tested. All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by some of the proteolytic enzymes, but were unaffected by catalase which indicates their proteinaceous nature. The compounds were heat stable up to 120°C for 20 min, and were active from pH 3.0 to 10.0. Highest bacteriocin activity was recorded under acidic conditions and activity decreased with increasing alkalinity.

Asian Journal of Microbiology Biotechnology and Environmental Sciences, Feb 5, 2014

Background: Community acquired infections due to extended-spectrum beta-lactamase-producing Enter... more Background: Community acquired infections due to extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) had been increased. The fecal flora of children in the community represents a huge potential reservoir for ESBLs which are located on highly transmissible plasmids. This study examined the prevalence of ESBL-PE fecal carriage, antimicrobial susceptibility pattern, possible risk factors, and characterized the genes encoding these ESBL enzymes in Lebanese children community. Methods: A total of 125 rectal swabs were taken from healthy children aged from 1 to 5 years. Detection of ESBLs was carried out using combination-disc method test and multiplex PCR. A questionnaire concerning child's lifestyle and risk factors for ESBL carriage was illustrated. Results: Thirty-one of 125 participants (24.8 %) carried ESBL-PE. Regular consumption of meat, and chicken were significantly associated with high carriage rate of ESBL-PE, while dairy products (milk, yogurt, cheese) association was non-significant. Intimate hygiene habits were found also affecting the carriage rate. Multiple bla genes were the most common, 48.4 % (15/31) of ESBL-PE carried both bla CTX-M and bla TEM , and 22.6 % (7/31) carried bla CTX-M , bla SHV , and bla TEM , 29 % (9) carried bla CTX-M only. Concerning CTX-M-types, CTX-M-9 was the most predominant (24/31) and mostly in combination with CTX-M-15 type. Conclusion: High rate of colonization in healthy children with ESBL-PE was observed, regular consumption of dietary products from animal source (meat or chicken) were associated with this colonization in the community in non-hospitalized children. To our best knowledge it is the first study about regular consumption of dairy product as a risk factor for ESBL-PE community carriage, the first data about the carriage rate of ESBL-PE in community children in Lebanon and Middle East, and for the wide dissemination of CTX-M-9 type in this population.

Environmental Geology, 2008

The aim of this study was to do a preliminary assessment of the hydrochemical and microbial groun... more The aim of this study was to do a preliminary assessment of the hydrochemical and microbial groundwater quality of the West Thrace region. Forty samples of groundwater collected from Edirne (Site 1) to Gelibolu (Site 2) were assessed for their suitability for human consumption. As 3was non-detectable in all the groundwater and Zn 2+ , Pb 2+ , F-, Cu 2+ , NH 4 + , Cn-PO 4 3and Clwere all below their respective European Union drinking water directive (EU-DWD) and Turkish food codex-drinking water directive (TFC-DWD). Maximum Acceptable Concentrations (MAC) Ni 2+ , Pb 2+ , Cd 2+ , Mg 2+ , Mn 2+ , and Ca 2+ levels were detected in upper maximum acceptable concentrations 77.5, 42.5, 35.0, 50.0, 50.0, and 32.5% of the groundwater samples, respectively. However, in terms of Cr 3+ , Ni 2+ and Pb 2+ , the differences between groundwaters of Sites 1 and 2 were significant (p < 0.05). Eight water samples (20%) had HPC exceeding the EU and Turkish water directive limit 20 CFU (Colony Forming Unit)/ml in drinking water and the maximum bacteria count recorded was 44 CFU/ml. Total coliforms, thermotolerant coliforms, E. coli, Enterococcus spp., Salmonella sp., Staphylococcus spp. and P. aeruginosa were detected in 25, 17.5, 15, 47.5, 15, 27.5, and 15% of the groundwater samples, respectively. Furthermore, heavy metals and trace elements were found after chemical analyzes in most samples. The pollution of groundwater come from a variety of sources, Meric and Ergene rivers, including land application of agricultural chemicals and organics wastes, infiltration of irrigation water, septic tanks, and infiltration of effluent from sewage treatment plants, pits, lagoons and ponds used storage.

Advances in Environmental Biology, 2014

Article history: Received 23 January 2014 Received in revised form 19 April 2014 Accepted 26 Apri... more Article history: Received 23 January 2014 Received in revised form 19 April 2014 Accepted 26 April 2014 Available online15 May 2014

International Food Research Journal, Dec 10, 2014

A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional ferm... more A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fermented milk (Jben, Klila, Raib and Lben), in order to evaluate their technological and probiotic properties. These strains were tested for their antimicrobial activity against Listeria monocytogenes using agar well diffusion technique. Only 11 strains were retained, they were also characterised in respect to their technological properties. The retained strains were identified by analyses of the 16S rDNA gene as; Lb. curvatus (1 strain), Ln. mesenteroides subsp mesenteroides (1 strain), Lb. plantarum (3 strains), Lb. brevis (2 strain), Lactobacillus acidophilus (2 strains), and Lactococcus lactis subsp lactis (2 strains). All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by the proteolytic enzymes. The compounds were heat stable up to 100°C for 20 min, and were active from pH 3.0 to 10.0. The enzymatic potential of the strains evaluated with API ZYM system show that all strains exhibited high leucine, cystine aminopeptidase and β-Galactosidase activities. Lactococcus strains were those that showed the greatest degree of proteolytic activity, however very low lipolytic and amylolytic capacity was detected for same strains. Two out of the 11 selected strains showed moderate survival rates under simulated gastric, however all tested strains showed a high stability under intestinal conditions. According to the results, the selected LAB strains could be used as potential probiotics to a possible inhibition of food-borne pathogenic bacteria and also would be of considerable interest to use as starter culture.

Applied and …, 2003

Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis we... more Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis were isolated from rice bran. One of the isolates, identified as Enterococcus faecalis RJ-11, exhibited a wide spectrum of growth inhibition with various gram-positive bacteria. A bacteriocin purified from culture fluid, designated enterocin RJ-11, was heat stable and was not sensitive to acid and alkaline conditions, but it was sensitive to several proteolytic enzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that enterocin RJ-11 had a molecular weight of 5,000 in its monomeric form. The amino acid sequence determined for purified enterocin RJ-11 exhibited high levels of similarity to the sequences of enterocins produced by Enterococcus faecium.

Applied and …, 2003

Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis we... more Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis were isolated from rice bran. One of the isolates, identified as Enterococcus faecalis RJ-11, exhibited a wide spectrum of growth inhibition with various gram-positive bacteria. A bacteriocin purified from culture fluid, designated enterocin RJ-11, was heat stable and was not sensitive to acid and alkaline conditions, but it was sensitive to several proteolytic enzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that enterocin RJ-11 had a molecular weight of 5,000 in its monomeric form. The amino acid sequence determined for purified enterocin RJ-11 exhibited high levels of similarity to the sequences of enterocins produced by Enterococcus faecium.

The aim of this study was to perform a pre-liminary assessment of the hydrochemical and microbial... more The aim of this study was to perform a pre-liminary assessment of the hydrochemical and microbial
groundwater quality of the Merdja plain (Te´bessa area).
Twenty samples of groundwater collected from Bekkaria
(Site 1) to Ain Chabro (Site 2) were assessed for their
suitability for human consumption. Groundwater from the
aquifer in the Merdja area can be divided into two major
groups according to geographical locations and chemical
compositions. Water in the center part of the study area is
characterized by the dominance of chloride, sulfate,
sodium, and potassium; whereas waters in the limestone
aquifers in the west are dominated by the same cations but
have higher concentrations of bicarbonate. Microbiological
parameters were determined in 13 groundwater samples
collected from the study area. Total coliforms, thermotol-erant coliforms,E. coli, Enterococcusspp.,Salmonellasp.,
Staphylococcusspp., and P. aeruginosawere detected in
96.36, 88.18, 100, 47.5, 97.27, 96.7, and 75 % of the
groundwater samples, respectively. The pollution of
groundwater comes from a variety of sources, Ouadi El
Kebir River, including land application of agricultural
chemicals and organic wastes, infiltration of irrigation
water, septic tanks, and infiltration of effluent from sewage
treatment plants, pits, lagoons, and ponds used for storage.

A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fer... more A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional
fermented milk (Jben, Klila, Raib and Lben), in order to evaluate their technological and
probiotic properties. These strains were tested for their antimicrobial activity against Listeria
monocytogenes using agar well diffusion technique. Only 11 strains were retained, they
were also characterised in respect to their technological properties. The retained strains were
identified by analyses of the 16S rDNA gene as; Lb. curvatus (1 strain), Ln. mesenteroides
subsp mesenteroides (1 strain),Lb. plantarum(3 strains), Lb. brevis (2 strain), Lactobacillus
acidophilus (2 strains), andLactococcus lactissubsp lactis(2 strains). All the antimicrobial
compounds produced by the selected lactic acid bacteria were fully or partially inactivated by
the proteolytic enzymes. The compounds were heat stable up to 100°C for 20 min, and were
active from pH 3.0 to 10.0. The enzymatic potential of the strains evaluated with API ZYM
system show that all strains exhibited high leucine, cystine aminopeptidase and β-Galactosidase
activities. Lactococcusstrains were those that showed the greatest degree of proteolytic activity,
however very low lipolytic and amylolytic capacity was detected for same strains. Two out of
the 11 selected strains showed moderate survival rates under simulated gastric, however all
tested strains showed a high stability under intestinal conditions. According to the results, the
selected LAB strains could be used as potential probiotics to a possible inhibition of food-borne
pathogenic bacteria and also would be of considerable interest to use as starter culture.

Research article, Jul 2014

Abstract- In the present study, a total of 108 of lactic acid bacteria (LAB) was isolated from Al... more Abstract- In the present study, a total of 108 of lactic acid bacteria (LAB) was isolated from Algerian traditional fermented dairy products (Jben, Klila, Raib and Lben) in order to evaluate their enzymatic activities (Proteolytic, α-amylase production, caseinolytic, lipolytic) and antimicrobial proprieties. Twelve representative isolates were selected and characterized with regard to their functional properties. The retained strains were identified using phenotypic and 16S rDNA gene analysis as; Lactococcus lactis subsp lactis (3 strains), L. lactis subsp. cremoris (1 strain), L. lactis subsp. lactis biovar. diacetylactis (2 strains), Lactobacillus plantarum (3 strains), Lactobacillus casei subsp. casei (2 strains) and Leuconostoc mesenteroides (1 strain). Lactococcus strains showed the greatest degree of acidifying and proteolytic activity. However, tow strains of Lactobacillus casei subsp. casei exhibited maximum caseinolytic activity. Furthermore, low lipolytic and amylolytic capacities were detected. The enzymatic potential evaluated with API ZYM system showed that all strains exhibited high Leucine arylamidase, Valine arylamidase and β-Galactosidase activities. Selected LAB were also tested for their antimicrobial activity against Listeria monocytogenes ATCC 7644 using agar well diffusion technique. All extracts of isolates were found to be fully inactivated by proteolytic enzymes, heat stable up to 100°C for 20 min and displayed inhibitory activity at pH from 3.0 to 10.0. Lactic acid bacteria isolated in this study play complex role in the traditional fermentation milk by their functional properties related to a specific enzyme spectrum, acidifying capacity, antimicrobial activities and probiotic properties.

Bacteria producing extended-spectrum β-lactamase (ESBL) among clinical isolates have been reporte... more Bacteria producing extended-spectrum β-lactamase (ESBL) among clinical isolates have been reported in many countries. However, data concerning the role of environmental contamination in the dissemination of (ESBL)-producing Enterobacteriaceae are currently lacking. In this context, the aim of this study was to investigate and characterise Enterobacteriaceae strains isolated from different places in a hospital and to determine the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. The bacterial isolates were identified on the basis of standard cultural, morphological and biochemical characteristics. Antibiotic susceptibility of the isolates was tested by disk diffusion method. A total of 637 strains of Enterobacteriaceae were isolated between 2007-2012. Susceptibility study showed that the imipenem was the most active antibiotic against overall enterobacteria with resistance rate of 2.51%, however the high resistance rates were observed to ampicilin (98.11%) and cephalixin (78.65%). The prevalence of ESBL was 136 (21.35%) and ESBL-producing strains were K. pneumoniae 66 (28.45 %), E. coli 31 (25.41%), S. marcescens 18 (19.15%), K. oxytoca 9 (17.31%), En .cloacae 5 (5.43%), C. freundii 04 (16%) and P. mirabilis 03 (15%). ESBL production was confirmed by double disk screening, combination disk method and E-test ESBL strip. All selected isolates harbored from one to four different plasmids with molecular sizes ranging from 5-170 kb. In general, most transconjugants acquired ceftazidime resistance by an ESBL gene encoded on the largest plasmid (>125 kb) found in the respective isolate. In addition, these transconjugants co-expressed other antibiotic resistance markers such as amikacin and ciprofloxacin.

In the last two decades, an extensive work has been carried out on bacteriocin like inhibitory su... more In the last two decades, an extensive work has been carried out on bacteriocin like inhibitory substance and also on the producing strains of lactic acid bacteria (LAB) for potential use as biopreservatives. In this study, a novel bacteriocin produced by the strain Lactobacillus curvatus LB65 isolated from traditional Algerian fermented milk product, was studied. The bacteriocinogenic strain was identified by both phenotypical and physiological tests combined with 16S rDNA sequence analysis. This bacteriocin which was designed curvaticin LB65, was sensitive to protease but insensitive to lipase and α-amylase, is stable between pH 4-10, and is heat resistant (15 min at 121°C). The novel bacteriocin exhibits inhibitory activity against food-spoiling bacteria and food-borne pathogens, including Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Micrococcus luteus, Klebsiella pneumonia, Escherichia coli, and against most of the lactic acid bacteria tested. Maximal production of bacteriocin was reached in the late stationary phase, and inhibitory activity declined within 24 h. The mode of action of curvaticin LB65 was determined to be bactericidal, as evidenced by its action upon Listeria monocytogenes. The novel bacteriocin, curvaticin LB65, was purified by ammonium sulphate precipitation followed by chromatography at normal pressure (QAE Sephadex A-25) and HPLC anion exchange chromatography on DEAE. The SDS-PAGE of the active fractions resulted in a single band with estimated molecular mass of 3.2 kDa. The technological properties of curvaticin LB65 suggest that it is a novel bacteriocin with potential application as a biopreservative in the food industry.

Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from indivi... more Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from individual household. They were evaluated for the presence of autochthonous bacteriocin-producing lactic acid bacteria. From 13 of these samples 52 strains of lactic acid bacteria were isolated, and shown to exhibit inhibitory activity against the indicator strain Listeria monocytogenes. Five of these inhibitor-producing isolates were selected for further study on the basis of their relatively wide antimicrobial spectrum. The inhibitory spectra of activity of the selected strains were evaluated against a range of Gram-positive and Gram-negative test organisms. Listeria monocytogenes and Staphylococcus aureus were the most sensitive indicator tested. All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by some of the proteolytic enzymes, but were unaffected by catalase which indicates their proteinaceous nature. The compounds were heat stable up to 120°C for 20 min, and were active from pH 3.0 to 10.0. Highest bacteriocin activity was recorded under acidic conditions and activity decreased with increasing alkalinity.

In the present work, 108 strains of lactic acid bacteria (LAB) were isolated from Algerian tradit... more In the present work, 108 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fermented milk (Jben, Klila, Raib and Lben) in order to evaluated their enzymatic activities (Proteolytic, caseinolytic, lipolytic, and α-amylase, activities) and their antimicrobial activity relative to different reference strains. Only 12 strains were retained, they were characterised in respect to their functional properties. The retained strains were identified phenotypically and analyses of the 16S rDNA gene as; Lactococcus lactis subsp lactis (3 strains), L. lactis subsp. cremoris (1 strain), L. lactis subsp. lactis biovar. diacetylactis (2 strains), Lactobacillus plantarum (3 strains), Lactobacillus casei subsp. casei (2 strain) and Leuconostoc mesenteroides (1 strain). Lactococcus strains were those that showed the greatest degree of acidifying and proteolytic activity, however the highest level of caseinolytic activity was shown by the CFE of tow strains of Lactobacillus c...

Asian Journal of Microbiology Biotechnology and Environmental Sciences, Apr 8, 2014

African Journal of Biotechnology, Aug 18, 2008

Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from indivi... more Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from individual household. They were evaluated for the presence of autochthonous bacteriocin-producing lactic acid bacteria. From 13 of these samples 52 strains of lactic acid bacteria were isolated, and shown to exhibit inhibitory activity against the indicator strain Listeria monocytogenes. Five of these inhibitor-producing isolates were selected for further study on the basis of their relatively wide antimicrobial spectrum. The inhibitory spectra of activity of the selected strains were evaluated against a range of Gram-positive and Gram-negative test organisms. Listeria monocytogenes and Staphylococcus aureus were the most sensitive indicator tested. All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by some of the proteolytic enzymes, but were unaffected by catalase which indicates their proteinaceous nature. The compounds were heat stable up to 120°C for 20 min, and were active from pH 3.0 to 10.0. Highest bacteriocin activity was recorded under acidic conditions and activity decreased with increasing alkalinity.

Asian Journal of Microbiology Biotechnology and Environmental Sciences, Feb 5, 2014

Background: Community acquired infections due to extended-spectrum beta-lactamase-producing Enter... more Background: Community acquired infections due to extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) had been increased. The fecal flora of children in the community represents a huge potential reservoir for ESBLs which are located on highly transmissible plasmids. This study examined the prevalence of ESBL-PE fecal carriage, antimicrobial susceptibility pattern, possible risk factors, and characterized the genes encoding these ESBL enzymes in Lebanese children community. Methods: A total of 125 rectal swabs were taken from healthy children aged from 1 to 5 years. Detection of ESBLs was carried out using combination-disc method test and multiplex PCR. A questionnaire concerning child's lifestyle and risk factors for ESBL carriage was illustrated. Results: Thirty-one of 125 participants (24.8 %) carried ESBL-PE. Regular consumption of meat, and chicken were significantly associated with high carriage rate of ESBL-PE, while dairy products (milk, yogurt, cheese) association was non-significant. Intimate hygiene habits were found also affecting the carriage rate. Multiple bla genes were the most common, 48.4 % (15/31) of ESBL-PE carried both bla CTX-M and bla TEM , and 22.6 % (7/31) carried bla CTX-M , bla SHV , and bla TEM , 29 % (9) carried bla CTX-M only. Concerning CTX-M-types, CTX-M-9 was the most predominant (24/31) and mostly in combination with CTX-M-15 type. Conclusion: High rate of colonization in healthy children with ESBL-PE was observed, regular consumption of dietary products from animal source (meat or chicken) were associated with this colonization in the community in non-hospitalized children. To our best knowledge it is the first study about regular consumption of dairy product as a risk factor for ESBL-PE community carriage, the first data about the carriage rate of ESBL-PE in community children in Lebanon and Middle East, and for the wide dissemination of CTX-M-9 type in this population.

Environmental Geology, 2008

The aim of this study was to do a preliminary assessment of the hydrochemical and microbial groun... more The aim of this study was to do a preliminary assessment of the hydrochemical and microbial groundwater quality of the West Thrace region. Forty samples of groundwater collected from Edirne (Site 1) to Gelibolu (Site 2) were assessed for their suitability for human consumption. As 3was non-detectable in all the groundwater and Zn 2+ , Pb 2+ , F-, Cu 2+ , NH 4 + , Cn-PO 4 3and Clwere all below their respective European Union drinking water directive (EU-DWD) and Turkish food codex-drinking water directive (TFC-DWD). Maximum Acceptable Concentrations (MAC) Ni 2+ , Pb 2+ , Cd 2+ , Mg 2+ , Mn 2+ , and Ca 2+ levels were detected in upper maximum acceptable concentrations 77.5, 42.5, 35.0, 50.0, 50.0, and 32.5% of the groundwater samples, respectively. However, in terms of Cr 3+ , Ni 2+ and Pb 2+ , the differences between groundwaters of Sites 1 and 2 were significant (p < 0.05). Eight water samples (20%) had HPC exceeding the EU and Turkish water directive limit 20 CFU (Colony Forming Unit)/ml in drinking water and the maximum bacteria count recorded was 44 CFU/ml. Total coliforms, thermotolerant coliforms, E. coli, Enterococcus spp., Salmonella sp., Staphylococcus spp. and P. aeruginosa were detected in 25, 17.5, 15, 47.5, 15, 27.5, and 15% of the groundwater samples, respectively. Furthermore, heavy metals and trace elements were found after chemical analyzes in most samples. The pollution of groundwater come from a variety of sources, Meric and Ergene rivers, including land application of agricultural chemicals and organics wastes, infiltration of irrigation water, septic tanks, and infiltration of effluent from sewage treatment plants, pits, lagoons and ponds used storage.

Advances in Environmental Biology, 2014

Article history: Received 23 January 2014 Received in revised form 19 April 2014 Accepted 26 Apri... more Article history: Received 23 January 2014 Received in revised form 19 April 2014 Accepted 26 April 2014 Available online15 May 2014

International Food Research Journal, Dec 10, 2014

A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional ferm... more A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fermented milk (Jben, Klila, Raib and Lben), in order to evaluate their technological and probiotic properties. These strains were tested for their antimicrobial activity against Listeria monocytogenes using agar well diffusion technique. Only 11 strains were retained, they were also characterised in respect to their technological properties. The retained strains were identified by analyses of the 16S rDNA gene as; Lb. curvatus (1 strain), Ln. mesenteroides subsp mesenteroides (1 strain), Lb. plantarum (3 strains), Lb. brevis (2 strain), Lactobacillus acidophilus (2 strains), and Lactococcus lactis subsp lactis (2 strains). All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by the proteolytic enzymes. The compounds were heat stable up to 100°C for 20 min, and were active from pH 3.0 to 10.0. The enzymatic potential of the strains evaluated with API ZYM system show that all strains exhibited high leucine, cystine aminopeptidase and β-Galactosidase activities. Lactococcus strains were those that showed the greatest degree of proteolytic activity, however very low lipolytic and amylolytic capacity was detected for same strains. Two out of the 11 selected strains showed moderate survival rates under simulated gastric, however all tested strains showed a high stability under intestinal conditions. According to the results, the selected LAB strains could be used as potential probiotics to a possible inhibition of food-borne pathogenic bacteria and also would be of considerable interest to use as starter culture.

Applied and …, 2003

Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis we... more Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis were isolated from rice bran. One of the isolates, identified as Enterococcus faecalis RJ-11, exhibited a wide spectrum of growth inhibition with various gram-positive bacteria. A bacteriocin purified from culture fluid, designated enterocin RJ-11, was heat stable and was not sensitive to acid and alkaline conditions, but it was sensitive to several proteolytic enzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that enterocin RJ-11 had a molecular weight of 5,000 in its monomeric form. The amino acid sequence determined for purified enterocin RJ-11 exhibited high levels of similarity to the sequences of enterocins produced by Enterococcus faecium.

Applied and …, 2003

Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis we... more Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis were isolated from rice bran. One of the isolates, identified as Enterococcus faecalis RJ-11, exhibited a wide spectrum of growth inhibition with various gram-positive bacteria. A bacteriocin purified from culture fluid, designated enterocin RJ-11, was heat stable and was not sensitive to acid and alkaline conditions, but it was sensitive to several proteolytic enzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that enterocin RJ-11 had a molecular weight of 5,000 in its monomeric form. The amino acid sequence determined for purified enterocin RJ-11 exhibited high levels of similarity to the sequences of enterocins produced by Enterococcus faecium.

The aim of this study was to perform a pre-liminary assessment of the hydrochemical and microbial... more The aim of this study was to perform a pre-liminary assessment of the hydrochemical and microbial
groundwater quality of the Merdja plain (Te´bessa area).
Twenty samples of groundwater collected from Bekkaria
(Site 1) to Ain Chabro (Site 2) were assessed for their
suitability for human consumption. Groundwater from the
aquifer in the Merdja area can be divided into two major
groups according to geographical locations and chemical
compositions. Water in the center part of the study area is
characterized by the dominance of chloride, sulfate,
sodium, and potassium; whereas waters in the limestone
aquifers in the west are dominated by the same cations but
have higher concentrations of bicarbonate. Microbiological
parameters were determined in 13 groundwater samples
collected from the study area. Total coliforms, thermotol-erant coliforms,E. coli, Enterococcusspp.,Salmonellasp.,
Staphylococcusspp., and P. aeruginosawere detected in
96.36, 88.18, 100, 47.5, 97.27, 96.7, and 75 % of the
groundwater samples, respectively. The pollution of
groundwater comes from a variety of sources, Ouadi El
Kebir River, including land application of agricultural
chemicals and organic wastes, infiltration of irrigation
water, septic tanks, and infiltration of effluent from sewage
treatment plants, pits, lagoons, and ponds used for storage.

A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fer... more A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional
fermented milk (Jben, Klila, Raib and Lben), in order to evaluate their technological and
probiotic properties. These strains were tested for their antimicrobial activity against Listeria
monocytogenes using agar well diffusion technique. Only 11 strains were retained, they
were also characterised in respect to their technological properties. The retained strains were
identified by analyses of the 16S rDNA gene as; Lb. curvatus (1 strain), Ln. mesenteroides
subsp mesenteroides (1 strain),Lb. plantarum(3 strains), Lb. brevis (2 strain), Lactobacillus
acidophilus (2 strains), andLactococcus lactissubsp lactis(2 strains). All the antimicrobial
compounds produced by the selected lactic acid bacteria were fully or partially inactivated by
the proteolytic enzymes. The compounds were heat stable up to 100°C for 20 min, and were
active from pH 3.0 to 10.0. The enzymatic potential of the strains evaluated with API ZYM
system show that all strains exhibited high leucine, cystine aminopeptidase and β-Galactosidase
activities. Lactococcusstrains were those that showed the greatest degree of proteolytic activity,
however very low lipolytic and amylolytic capacity was detected for same strains. Two out of
the 11 selected strains showed moderate survival rates under simulated gastric, however all
tested strains showed a high stability under intestinal conditions. According to the results, the
selected LAB strains could be used as potential probiotics to a possible inhibition of food-borne
pathogenic bacteria and also would be of considerable interest to use as starter culture.

Research article, Jul 2014

Abstract- In the present study, a total of 108 of lactic acid bacteria (LAB) was isolated from Al... more Abstract- In the present study, a total of 108 of lactic acid bacteria (LAB) was isolated from Algerian traditional fermented dairy products (Jben, Klila, Raib and Lben) in order to evaluate their enzymatic activities (Proteolytic, α-amylase production, caseinolytic, lipolytic) and antimicrobial proprieties. Twelve representative isolates were selected and characterized with regard to their functional properties. The retained strains were identified using phenotypic and 16S rDNA gene analysis as; Lactococcus lactis subsp lactis (3 strains), L. lactis subsp. cremoris (1 strain), L. lactis subsp. lactis biovar. diacetylactis (2 strains), Lactobacillus plantarum (3 strains), Lactobacillus casei subsp. casei (2 strains) and Leuconostoc mesenteroides (1 strain). Lactococcus strains showed the greatest degree of acidifying and proteolytic activity. However, tow strains of Lactobacillus casei subsp. casei exhibited maximum caseinolytic activity. Furthermore, low lipolytic and amylolytic capacities were detected. The enzymatic potential evaluated with API ZYM system showed that all strains exhibited high Leucine arylamidase, Valine arylamidase and β-Galactosidase activities. Selected LAB were also tested for their antimicrobial activity against Listeria monocytogenes ATCC 7644 using agar well diffusion technique. All extracts of isolates were found to be fully inactivated by proteolytic enzymes, heat stable up to 100°C for 20 min and displayed inhibitory activity at pH from 3.0 to 10.0. Lactic acid bacteria isolated in this study play complex role in the traditional fermentation milk by their functional properties related to a specific enzyme spectrum, acidifying capacity, antimicrobial activities and probiotic properties.

Bacteria producing extended-spectrum β-lactamase (ESBL) among clinical isolates have been reporte... more Bacteria producing extended-spectrum β-lactamase (ESBL) among clinical isolates have been reported in many countries. However, data concerning the role of environmental contamination in the dissemination of (ESBL)-producing Enterobacteriaceae are currently lacking. In this context, the aim of this study was to investigate and characterise Enterobacteriaceae strains isolated from different places in a hospital and to determine the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. The bacterial isolates were identified on the basis of standard cultural, morphological and biochemical characteristics. Antibiotic susceptibility of the isolates was tested by disk diffusion method. A total of 637 strains of Enterobacteriaceae were isolated between 2007-2012. Susceptibility study showed that the imipenem was the most active antibiotic against overall enterobacteria with resistance rate of 2.51%, however the high resistance rates were observed to ampicilin (98.11%) and cephalixin (78.65%). The prevalence of ESBL was 136 (21.35%) and ESBL-producing strains were K. pneumoniae 66 (28.45 %), E. coli 31 (25.41%), S. marcescens 18 (19.15%), K. oxytoca 9 (17.31%), En .cloacae 5 (5.43%), C. freundii 04 (16%) and P. mirabilis 03 (15%). ESBL production was confirmed by double disk screening, combination disk method and E-test ESBL strip. All selected isolates harbored from one to four different plasmids with molecular sizes ranging from 5-170 kb. In general, most transconjugants acquired ceftazidime resistance by an ESBL gene encoded on the largest plasmid (>125 kb) found in the respective isolate. In addition, these transconjugants co-expressed other antibiotic resistance markers such as amikacin and ciprofloxacin.

In the last two decades, an extensive work has been carried out on bacteriocin like inhibitory su... more In the last two decades, an extensive work has been carried out on bacteriocin like inhibitory substance and also on the producing strains of lactic acid bacteria (LAB) for potential use as biopreservatives. In this study, a novel bacteriocin produced by the strain Lactobacillus curvatus LB65 isolated from traditional Algerian fermented milk product, was studied. The bacteriocinogenic strain was identified by both phenotypical and physiological tests combined with 16S rDNA sequence analysis. This bacteriocin which was designed curvaticin LB65, was sensitive to protease but insensitive to lipase and α-amylase, is stable between pH 4-10, and is heat resistant (15 min at 121°C). The novel bacteriocin exhibits inhibitory activity against food-spoiling bacteria and food-borne pathogens, including Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Micrococcus luteus, Klebsiella pneumonia, Escherichia coli, and against most of the lactic acid bacteria tested. Maximal production of bacteriocin was reached in the late stationary phase, and inhibitory activity declined within 24 h. The mode of action of curvaticin LB65 was determined to be bactericidal, as evidenced by its action upon Listeria monocytogenes. The novel bacteriocin, curvaticin LB65, was purified by ammonium sulphate precipitation followed by chromatography at normal pressure (QAE Sephadex A-25) and HPLC anion exchange chromatography on DEAE. The SDS-PAGE of the active fractions resulted in a single band with estimated molecular mass of 3.2 kDa. The technological properties of curvaticin LB65 suggest that it is a novel bacteriocin with potential application as a biopreservative in the food industry.

Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from indivi... more Twenty samples of traditional fermented milk "Raib" were collected in eastern Algeria from individual household. They were evaluated for the presence of autochthonous bacteriocin-producing lactic acid bacteria. From 13 of these samples 52 strains of lactic acid bacteria were isolated, and shown to exhibit inhibitory activity against the indicator strain Listeria monocytogenes. Five of these inhibitor-producing isolates were selected for further study on the basis of their relatively wide antimicrobial spectrum. The inhibitory spectra of activity of the selected strains were evaluated against a range of Gram-positive and Gram-negative test organisms. Listeria monocytogenes and Staphylococcus aureus were the most sensitive indicator tested. All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by some of the proteolytic enzymes, but were unaffected by catalase which indicates their proteinaceous nature. The compounds were heat stable up to 120°C for 20 min, and were active from pH 3.0 to 10.0. Highest bacteriocin activity was recorded under acidic conditions and activity decreased with increasing alkalinity.