Nivin Al-alami - Academia.edu (original) (raw)
Papers by Nivin Al-alami
International Journal of Food Microbiology, 2016
The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria ... more The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus and Campylobacter jejuni in laboratory contaminated live clam (Venerupis philippinarum) and mussel (Mytilus edulis) was investigated. The initial levels of bacterial contamination were: in clam 4.9 to 5.7log10CFU/g, and in mussel 5.1 to 5.5log10CFU/g. Two types of AEW were used for treatment time intervals of 1 and 2h: strong (SAEW) with an available chlorine concentration (ACC) of 20mg/L, pH=3.1, and an oxidation-reduction potential (ORP) of 1150mV, and weak (WAEW) at ACC of 10mg/L, pH=3.55 and ORP of 950mV. SAEW and WAEW exhibited significant inhibitory activity against inoculated bacteria in both shellfish species with significant differences compared to saline solutions treatments (1-2% NaCl) and untreated controls (0h). SAEW showed the largest inhibitory activity, the extent of reduction (log10CFU/g) ranged from 1.4-1.7 for E. coli O104:H4; 1.0-1.6 for L. monocytogenes; 1.3-1.6 for A. hydrophila; 1.0-1.5 for V. parahaemolyticus; and 1.5-2.2 for C. jejuni in both types of shellfish. In comparison, significantly (P<0.05) lower inhibitory effect of WAEW was achieved compared to SAEW, where the extent of reduction (log10CFU/g) ranged from 0.7-1.1 for E. coli O104:H4; 0.6-0.9 for L. monocytogenes; 0.6-1.3 for A. hydrophila; 0.7-1.3 for V. parahaemolyticus; and 0.8-1.9 for C. jejuni in both types of shellfish. Among all bacterial strains examined in this study, AEW induced less bacterial injury (~0.1-1.0log10CFU/g) and more inactivation effect. This study revealed that AEW (10-20mg/L ACC) could be used to reduce bacterial contamination in live clam and mussel, which may help control possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish.
Journal of Food Science, 2016
Bactericidal activity of neutral electrolyzed water (NEW), quaternary ammonium (QUAT), and lactic... more Bactericidal activity of neutral electrolyzed water (NEW), quaternary ammonium (QUAT), and lactic acid-based solutions was investigated using a manual spraying technique against Salmonella Typhimurium, Escherichia coli O157:H7, Campylobacter jejuni, Listeria monocytogenes and Staphylococcus aureus that were inoculated onto the surface of scarred polypropylene and wooden food cutting boards. Antimicrobial activity was also examined when using cutting boards in preparation of raw chopped beef, chicken tenders or salmon fillets. Viable counts of survivors were determined as log10 CFU/100 cm(2) within 0 (untreated control), 1, 3, and 5 min of treatment at ambient temperature. Within the first minute of treatment, NEW and QUAT solutions caused more than 3 log10 bacterial reductions on polypropylene surfaces whereas less than 3 log10 reductions were achieved on wooden surfaces. After 5 min of treatment, more than 5 log10 reductions were achieved for all bacterial strains inoculated onto polypropylene surfaces. Using NEW and QUAT solutions within 5 min reduced Gram-negative bacteria by 4.58 to 4.85 log10 compared to more than 5 log10 reductions in Gram-positive bacteria inoculated onto wooden surfaces. Lactic acid treatment was significantly less effective (P < 0.05) compared to NEW and QUAT treatments. A decline in antimicrobial effectiveness was observed (0.5 to <2 log10 reductions were achieved within the first minute) when both cutting board types were used to prepare raw chopped beef, chicken tenders or salmon fillets.
Journal of food protection, 2015
This study investigated the growth and survival of three foodborne pathogens (Clostridium perfrin... more This study investigated the growth and survival of three foodborne pathogens (Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes) in beef (7% fat) and nutrient broth under different oxygen levels. Samples were tested under anoxic (<0.5%), microoxic (6 to 8%), and oxic (20%) conditions during storage at 7°C for 14 days and at 22°C for 5 days. Two initial inoculum concentrations were used (1 and 2 log CFU per g of beef or per ml of broth). The results show that C. perfringens could grow in beef at 22°C, with an increase of approximately 5 log under anoxic conditions and a 1-log increase under microoxic conditions. However, C. perfringens could not survive in beef held at 7°C under microoxic and oxic storage conditions after 14 days. In an anoxic environment, C. perfringens survived in beef samples held at 7°C, with a 1-log reduction. A cell decline was observed at 2 log under these conditions, with no surviving cells at the 1-log level. However, the results s...
Efficient Management of Wastewater, 2008
Survey on wastewater irrigation, with emphasis on 44 the Nakivubo drainage channel in Kampala Kha... more Survey on wastewater irrigation, with emphasis on 44 the Nakivubo drainage channel in Kampala Khalid Y. Muwembe* Graywater treatment and reuse for water and food security 49 in Lebanon N. Haddad, L. Kaï, and C. Mahfoud* Effects of sewage sludge on heavy metal accumulation in 57 soil and plants, and on crop productivity in Aleppo governorate Fate of pathogens in tomato plants and soil irrigated with 86 secondary treated wastewater M. Halalsheh*, L. Abu Ghunmi, N. Al-Alami, and M. Fayyad Effect of wastewater application on parsley yield and 93 heavy metals accumulation in soil and plants A. Hamdan*, and A. Arslan
Journal of Food Protection, 2011
Journal of Agricultural and Food Chemistry, 2008
The effect of chlorine-induced bacterial injury on spectral features using Fourier transform infr... more The effect of chlorine-induced bacterial injury on spectral features using Fourier transform infrared (FT-IR) absorbance spectroscopy was studied using a mixed bacterial culture of (1:1) ca. 500 CFU/ mL each Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 15442 in 0.9% saline. Bacterial cells were treated with 0, 0.3, or 1.0 ppm of initial free chlorine (21°C, 1 h of contact time). Chlorine-injured and dead bacterial cells retained the ATR spectral properties of uninjured or live cells in the region of C-O-C stretching vibrations of polysaccharides, indicative of the cell wall peptidoglycan layer and lipopolysaccharide outer leaflet. This confirms the observations of others that extensive bacterial membrane damage is not a key factor in the inactivation of bacteria by chlorine. The bactericidal effect of chlorine caused changes in the spectral features of bacterial ester functional groups of lipids, structural proteins, and nucleic acids, with apparent denaturation reflected between 1800 and 1300 cm -1 for injured bacterial cells. Three-dimensional principal component analysis (PCA) showed distinct segregation and clustering of chlorine-treated and untreated cells. Cells exposed to chlorine at 0.3 or 1.0 ppm could be distinguished from the untreated control 73 and 80% of the time, respectively, using soft independent modeling of class analogy (SIMCA) analysis. This study suggests that FT-IR spectroscopy may be applicable for detecting the presence of injured and viable but not culturable (VBNC) waterborne pathogens that are underestimated or not discernible using conventional microbial techniques.
Journal of Agricultural and Food Chemistry, 2006
Fourier transform infrared (FT-IR) spectroscopy and multivariate analysis were used to identify P... more Fourier transform infrared (FT-IR) spectroscopy and multivariate analysis were used to identify Pseudomonas aeruginosa and Escherichia coli ATCC 25922 inoculated into bottled drinking water. Three inoculation treatments were examined as examined: (i) E. coli ATCC 25922 (N ) 3), (ii) P. aeruginosa (N ) 3), and (iii) a 1:1 (v:v) mixed culture of both P. aeruginosa and E. coli ATCC 25922 (N ) 3). The control treatment was noninoculated drinking water (N ) 3). Second derivative transformation and loadings plots over the range of 1800-900 cm -1 indicate variations in the following bacterial constituents: amide I band ca. 1650 cm -1 , amide II band ca. 1540 cm -1 , phosphodiester backbone of nucleic acids ca. 1242 and 1080 cm -1 , and polysaccharide compounds ca. 1050-950 cm -1 . Cells with the different treatments were clearly segregated from a mean centered principal component analysis. By using soft independent modeling of class analogy analysis, spectra from a given treatment could be correctly classified 83-88% of the time. These results suggest that FT-IR spectroscopy can determine whether a pure culture is present, in addition to confirming that this method can discriminate between closely related bacteria based on differences in biochemical and phenotypic characteristics that can be detected in this spectral region.
Food Microbiology, 2011
The inactivation and sublethal injury of Escherichia coli O157:H7, Campylobacter jejuni and Pseud... more The inactivation and sublethal injury of Escherichia coli O157:H7, Campylobacter jejuni and Pseudomonas aeruginosa at three temperatures (22 C, 4 C and À18 C) were studied using traditional microbiological tests and mid-infrared spectroscopy (4000e400 cm À1 ). Bacteria were cultivated in diluted nutrient matrices with a high initial inoculation (∼10 7 CFU/ml) levels. Both E. coli O157:H7 and P. aeruginosa survived and cell numbers increased at 22 C for 5 days while C. jejuni numbers decreased one log 10 CFU/ml. A two log CFU/ml decrease was observed for the three pathogens held at 4 C for 12 days. C. jejuni survived poorly following incubation at À18 C for 20 days while levels of E. coli O157:H7 and P. aeruginosa remained high (10 4 CFU/ml). Temperature stress response of microbes was observed by infrared spectroscopy in polysaccharide, protein, lipid, and nucleic acid regions and was strain specific. Level of cold injury could be predicted using cluster, discriminant function and class analog analysis models. Pathogens may produce oligosaccharides and potentially other components in response to stress as indicated by changes in spectral features at 1200e900 cm À1 following freezing.
Journal of Rapid Methods and Automation in Microbiology, 2008
This study examined the potential of Fourier transform infrared (FT-IR) absorbance spectroscopy t... more This study examined the potential of Fourier transform infrared (FT-IR) absorbance spectroscopy to detect biochemical changes in bacterial cells that occur during bacterial growth phases in batch culture. Two bacterial strains, Escherichia coli ATCC 25922 and Listeria innocua ATCC 51742 were cultured in brain heart infusion (BHI) broth and incubated at 37C and cells recovered 7 Corresponding 73 at: the lag phase (3 h), the log phase (7 h), the stationary phase (24 h), and the death phase (10 days) from incubation in BHI (n = 2).
International Journal of Food Microbiology, 2016
The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria ... more The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus and Campylobacter jejuni in laboratory contaminated live clam (Venerupis philippinarum) and mussel (Mytilus edulis) was investigated. The initial levels of bacterial contamination were: in clam 4.9 to 5.7log10CFU/g, and in mussel 5.1 to 5.5log10CFU/g. Two types of AEW were used for treatment time intervals of 1 and 2h: strong (SAEW) with an available chlorine concentration (ACC) of 20mg/L, pH=3.1, and an oxidation-reduction potential (ORP) of 1150mV, and weak (WAEW) at ACC of 10mg/L, pH=3.55 and ORP of 950mV. SAEW and WAEW exhibited significant inhibitory activity against inoculated bacteria in both shellfish species with significant differences compared to saline solutions treatments (1-2% NaCl) and untreated controls (0h). SAEW showed the largest inhibitory activity, the extent of reduction (log10CFU/g) ranged from 1.4-1.7 for E. coli O104:H4; 1.0-1.6 for L. monocytogenes; 1.3-1.6 for A. hydrophila; 1.0-1.5 for V. parahaemolyticus; and 1.5-2.2 for C. jejuni in both types of shellfish. In comparison, significantly (P&amp;lt;0.05) lower inhibitory effect of WAEW was achieved compared to SAEW, where the extent of reduction (log10CFU/g) ranged from 0.7-1.1 for E. coli O104:H4; 0.6-0.9 for L. monocytogenes; 0.6-1.3 for A. hydrophila; 0.7-1.3 for V. parahaemolyticus; and 0.8-1.9 for C. jejuni in both types of shellfish. Among all bacterial strains examined in this study, AEW induced less bacterial injury (~0.1-1.0log10CFU/g) and more inactivation effect. This study revealed that AEW (10-20mg/L ACC) could be used to reduce bacterial contamination in live clam and mussel, which may help control possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish.
Journal of Food Science, 2016
Bactericidal activity of neutral electrolyzed water (NEW), quaternary ammonium (QUAT), and lactic... more Bactericidal activity of neutral electrolyzed water (NEW), quaternary ammonium (QUAT), and lactic acid-based solutions was investigated using a manual spraying technique against Salmonella Typhimurium, Escherichia coli O157:H7, Campylobacter jejuni, Listeria monocytogenes and Staphylococcus aureus that were inoculated onto the surface of scarred polypropylene and wooden food cutting boards. Antimicrobial activity was also examined when using cutting boards in preparation of raw chopped beef, chicken tenders or salmon fillets. Viable counts of survivors were determined as log10 CFU/100 cm(2) within 0 (untreated control), 1, 3, and 5 min of treatment at ambient temperature. Within the first minute of treatment, NEW and QUAT solutions caused more than 3 log10 bacterial reductions on polypropylene surfaces whereas less than 3 log10 reductions were achieved on wooden surfaces. After 5 min of treatment, more than 5 log10 reductions were achieved for all bacterial strains inoculated onto polypropylene surfaces. Using NEW and QUAT solutions within 5 min reduced Gram-negative bacteria by 4.58 to 4.85 log10 compared to more than 5 log10 reductions in Gram-positive bacteria inoculated onto wooden surfaces. Lactic acid treatment was significantly less effective (P &amp;lt; 0.05) compared to NEW and QUAT treatments. A decline in antimicrobial effectiveness was observed (0.5 to &amp;lt;2 log10 reductions were achieved within the first minute) when both cutting board types were used to prepare raw chopped beef, chicken tenders or salmon fillets.
Journal of food protection, 2015
This study investigated the growth and survival of three foodborne pathogens (Clostridium perfrin... more This study investigated the growth and survival of three foodborne pathogens (Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes) in beef (7% fat) and nutrient broth under different oxygen levels. Samples were tested under anoxic (<0.5%), microoxic (6 to 8%), and oxic (20%) conditions during storage at 7°C for 14 days and at 22°C for 5 days. Two initial inoculum concentrations were used (1 and 2 log CFU per g of beef or per ml of broth). The results show that C. perfringens could grow in beef at 22°C, with an increase of approximately 5 log under anoxic conditions and a 1-log increase under microoxic conditions. However, C. perfringens could not survive in beef held at 7°C under microoxic and oxic storage conditions after 14 days. In an anoxic environment, C. perfringens survived in beef samples held at 7°C, with a 1-log reduction. A cell decline was observed at 2 log under these conditions, with no surviving cells at the 1-log level. However, the results s...
Efficient Management of Wastewater, 2008
Survey on wastewater irrigation, with emphasis on 44 the Nakivubo drainage channel in Kampala Kha... more Survey on wastewater irrigation, with emphasis on 44 the Nakivubo drainage channel in Kampala Khalid Y. Muwembe* Graywater treatment and reuse for water and food security 49 in Lebanon N. Haddad, L. Kaï, and C. Mahfoud* Effects of sewage sludge on heavy metal accumulation in 57 soil and plants, and on crop productivity in Aleppo governorate Fate of pathogens in tomato plants and soil irrigated with 86 secondary treated wastewater M. Halalsheh*, L. Abu Ghunmi, N. Al-Alami, and M. Fayyad Effect of wastewater application on parsley yield and 93 heavy metals accumulation in soil and plants A. Hamdan*, and A. Arslan
Journal of Food Protection, 2011
Journal of Agricultural and Food Chemistry, 2008
The effect of chlorine-induced bacterial injury on spectral features using Fourier transform infr... more The effect of chlorine-induced bacterial injury on spectral features using Fourier transform infrared (FT-IR) absorbance spectroscopy was studied using a mixed bacterial culture of (1:1) ca. 500 CFU/ mL each Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 15442 in 0.9% saline. Bacterial cells were treated with 0, 0.3, or 1.0 ppm of initial free chlorine (21°C, 1 h of contact time). Chlorine-injured and dead bacterial cells retained the ATR spectral properties of uninjured or live cells in the region of C-O-C stretching vibrations of polysaccharides, indicative of the cell wall peptidoglycan layer and lipopolysaccharide outer leaflet. This confirms the observations of others that extensive bacterial membrane damage is not a key factor in the inactivation of bacteria by chlorine. The bactericidal effect of chlorine caused changes in the spectral features of bacterial ester functional groups of lipids, structural proteins, and nucleic acids, with apparent denaturation reflected between 1800 and 1300 cm -1 for injured bacterial cells. Three-dimensional principal component analysis (PCA) showed distinct segregation and clustering of chlorine-treated and untreated cells. Cells exposed to chlorine at 0.3 or 1.0 ppm could be distinguished from the untreated control 73 and 80% of the time, respectively, using soft independent modeling of class analogy (SIMCA) analysis. This study suggests that FT-IR spectroscopy may be applicable for detecting the presence of injured and viable but not culturable (VBNC) waterborne pathogens that are underestimated or not discernible using conventional microbial techniques.
Journal of Agricultural and Food Chemistry, 2006
Fourier transform infrared (FT-IR) spectroscopy and multivariate analysis were used to identify P... more Fourier transform infrared (FT-IR) spectroscopy and multivariate analysis were used to identify Pseudomonas aeruginosa and Escherichia coli ATCC 25922 inoculated into bottled drinking water. Three inoculation treatments were examined as examined: (i) E. coli ATCC 25922 (N ) 3), (ii) P. aeruginosa (N ) 3), and (iii) a 1:1 (v:v) mixed culture of both P. aeruginosa and E. coli ATCC 25922 (N ) 3). The control treatment was noninoculated drinking water (N ) 3). Second derivative transformation and loadings plots over the range of 1800-900 cm -1 indicate variations in the following bacterial constituents: amide I band ca. 1650 cm -1 , amide II band ca. 1540 cm -1 , phosphodiester backbone of nucleic acids ca. 1242 and 1080 cm -1 , and polysaccharide compounds ca. 1050-950 cm -1 . Cells with the different treatments were clearly segregated from a mean centered principal component analysis. By using soft independent modeling of class analogy analysis, spectra from a given treatment could be correctly classified 83-88% of the time. These results suggest that FT-IR spectroscopy can determine whether a pure culture is present, in addition to confirming that this method can discriminate between closely related bacteria based on differences in biochemical and phenotypic characteristics that can be detected in this spectral region.
Food Microbiology, 2011
The inactivation and sublethal injury of Escherichia coli O157:H7, Campylobacter jejuni and Pseud... more The inactivation and sublethal injury of Escherichia coli O157:H7, Campylobacter jejuni and Pseudomonas aeruginosa at three temperatures (22 C, 4 C and À18 C) were studied using traditional microbiological tests and mid-infrared spectroscopy (4000e400 cm À1 ). Bacteria were cultivated in diluted nutrient matrices with a high initial inoculation (∼10 7 CFU/ml) levels. Both E. coli O157:H7 and P. aeruginosa survived and cell numbers increased at 22 C for 5 days while C. jejuni numbers decreased one log 10 CFU/ml. A two log CFU/ml decrease was observed for the three pathogens held at 4 C for 12 days. C. jejuni survived poorly following incubation at À18 C for 20 days while levels of E. coli O157:H7 and P. aeruginosa remained high (10 4 CFU/ml). Temperature stress response of microbes was observed by infrared spectroscopy in polysaccharide, protein, lipid, and nucleic acid regions and was strain specific. Level of cold injury could be predicted using cluster, discriminant function and class analog analysis models. Pathogens may produce oligosaccharides and potentially other components in response to stress as indicated by changes in spectral features at 1200e900 cm À1 following freezing.
Journal of Rapid Methods and Automation in Microbiology, 2008
This study examined the potential of Fourier transform infrared (FT-IR) absorbance spectroscopy t... more This study examined the potential of Fourier transform infrared (FT-IR) absorbance spectroscopy to detect biochemical changes in bacterial cells that occur during bacterial growth phases in batch culture. Two bacterial strains, Escherichia coli ATCC 25922 and Listeria innocua ATCC 51742 were cultured in brain heart infusion (BHI) broth and incubated at 37C and cells recovered 7 Corresponding 73 at: the lag phase (3 h), the log phase (7 h), the stationary phase (24 h), and the death phase (10 days) from incubation in BHI (n = 2).