Tatsinkou Fossi Bertrand | University of Buea (original) (raw)

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Papers by Tatsinkou Fossi Bertrand

The occurrence of antibiotic resistant Salmonella is one of the major threats to the poultry indu... more The occurrence of antibiotic resistant Salmonella is one of the major threats to the poultry industry. The use of probiotic strains is a promising alternative for the control and eradication of Salmonella in poultry. This study aims at producing and assessing the potential of Lactobacillus rhamnosus (IS9) strain to reduce Salmonella enterica serovar
Enteridis and Typhimurium common in poultry. Pathogen-free chicks were orally administered by gavage with 1.0 x 109 CFU / ml of Lactobacillus rhamnosus (IS9) suspended in 0.1 ml of sterile water and 24 h later were challenged in separate experiments with S. Enteritidis and S. Typhimurium. There was a significant reduction (P0.05) in S. Enterisdis and S. Typhimurium in the small intestine of infected birds. The action of L. rhamnosus (IS9) was more important in 14-days old chicks. Salmonella count was nil in duodenum, colon and caeca of 14-days old chicks pre-dosed with a single dosed of L. rhamnosus (IS9). Weekly analysis of caeca swabs of chicks pre-dosed with L. rhamnosus
(IS9) showed significant reduction (P0.05) in Salmonella while the caeca population of lactobacilli increases.

An amylolytic yeast strain was isolated from starchy soils (flour mills environment, flour market... more An amylolytic yeast strain was isolated from starchy soils (flour mills environment, flour market, cassava farms after harvesting and transformation of tubers) and its enzyme productivity and activity evaluated. The enzyme synthesis was optimum at 30°C when initial pH of fermentation medium was 4.5. After extraction and partial purification, the enzyme remained stable in a range of temperature and pH between 20°C-60°C and 2-8 pH respectively. The optimum enzyme activity was displayed at 70°C and pH 5.5 and 6.5. The thermostability of the enzyme was comparable to that of amylases from bacteria.

The present study was undertaken to assess the inhibitory potential of lactic acid bacteria isola... more The present study was undertaken to assess the inhibitory potential of lactic acid bacteria isolated from traditionally processed corn-beer and palm-wine on Escherichia coli, Salmonella typhi and Staphylococcus aureus. Lactic acid bacteria were isolated on MRS agar using pour plate method. The catalase negative and Gram positive isolates were selected as presumptive lactic acid bacteria and were biochemically characterized using the API 50 CHL BioMerieux kit to identify them at species level. The LAB isolates were then assessed for antimicrobial activity potentials against food-borne pathogens. Thirteen LAB isolates which constituted nine different species namely: Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus acidophilus, Lactobacillus bulgaricus, Leuconostoc mesenteroides, Leuconostoc carnosum, Pedioccocus acidilactici and Lactobacillus pentosus were isolated from these two beverages. The entire LAB isolates demonstrated great potentials to inhibit the test pathogens. P. acidilactici from corn-beer exhibited the overall highest inhibitory activity with zones of inhibition of 19, 20 and 16 mm on E. coli, S. typhi and S. aureus, respectively; while the isolate from palm-wine, L. pentosus exerted the highest antimicrobial action on the test pathogens. It was observed that most of the LAB isolates inhibited the indicator pathogens mainly by bacteriocin production. S. typhi was the most susceptible food-borne bacterial pathogen to the inhibitory activity of the LAB isolates, followed by E. coli.

Fruits and vegetables are important part of the diet of most humans. They are highly nutritive, a... more Fruits and vegetables are important part of the diet of most humans. They are highly nutritive, and constitute an important source of minerals and vitamins. However the widely consumed fruits and vegetables are rich in phytic acid that causes reduction in the absorption and bioavailability of nutrients and minerals. The use of probiotic bacteria such as phytic acid degrading lactic acid bacteria (LAB) in the diet could help to prevent the chelation of mineral by phytates. Therefore the aim of this study was to screen, select and characterise phytate degrading LAB isolated from fruits and vegetables. LAB were isolated from 106 fruits and vegetables samples collected in Buea and Limbe using pour plating method on de Man Rogosa and Sharpe (MRS) agar. The isolates were characterised using the catalase test, Gram staining and the API 50 CHL BioMerieux kit. The phytate degrading activity of LAB was carried out qualitatively on modified MRS agar by point inoculation and the phytase activity was quantified in broth by spectrophotometric method. Thirty three LAB isolates were isolated. In which Twenty one produced a clear zone of hydrolysis on modified MRS agar demonstrating their phytate degrading potentials. Lactobacillus rhamnosus and Lactobacillus plantarum showed the highest phytate degradation both qualitatively and quantitatively, producing the highest amounts of the enzyme phytase. Both isolates also had a good tolerance to bile and acidic conditions, there by showing their ability to survive in the gastrointestinal track. This work shows a new perspective on the phytate degrading power of LAB thereby highlighting the ability of LAB to decrease malnutrition due to mineral deficiency.

Lactic acid bacteria are potential source of enzymes that can be used in food biotechnology becau... more Lactic acid bacteria are potential source of enzymes that can be used in food biotechnology because they are generally regarded as safe. A highly thermostable α-amylase producing lactic acid bacterium, Lactobacillus fermentum 04BBA19 isolated from a soil of the western region of Cameroon was characterized for its starch degrading activity and biochemical properties. The bacterium exhibited maximal production of the enzyme at temperature 45°C, and within pH range of 4.0 to 5.0. The main environmental conditions affecting enzyme productivity were the nature of substrate, the nitrogen source, the minerals content and the presence of surfactants. The enzyme was identified as an α-amylase fragment exhibiting maximum activity and stability in temperature and pH ranges of 60-70°C and 4.0-7.0 respectively, with a very high thermostability revealed by the retention of 100% of original activity after pre-incubation for 30 min at 80°C. The stability improved considerably with addition of 0.1% (w/v) CaCl 2 .2H 2 O; the half live of the enzyme under the above conditions was 6 h at 80°C.

The present study aims at screening and isolates thermostable alkaline protease producing bacteri... more The present study aims at screening and isolates thermostable alkaline protease producing bacteria from soil sample in the northern part of Cameroon, and characterizes their enzyme. Samples of soil were collected from four (04) North Cameroonian towns (Ngaoundere, Garoua, Figuil and Maroua). Six (06) isolates showed important
proteolytic activity on skim milk agar. The strain N2.3.5 from Ngaoundere showed the largest hydrolysis halo (24
mm) and was selected for protease production. The partial identification of strain N2.3.5 through morphological and biochemical characterization enabled us to classify it as belonging to the genus Bacillus sp. The growth of the strain N2.3.5 and its enzyme production profile showed that the growth of the bacteria was a diauxic type, and that the protease production was not directly associated with the microbial growth. In a medium composed of soya flour, corn
flour, yeast extract and at alkaline pH, following the monitoring of each of these parameters by a complete factorial experimental design, the pH value of 10 was found to be significant for an optimal growth. Meanwhile, the corn flour, the soya flour and the yeast extract did not have a consequent influence on the protease production by the bacteria,
under the chosen experimental conditions. The extracellular protease produced by Bacillus sp N235 was partially purified using a precipitation with ammonium sulphate, a dialysis and a gel filtration on sephadex G-75. A specific activity of 1516.7 U/mg and a purification yield of 37.63% were obtained. The partially purified enzyme was able to maintain its activity after been heat-treated at 80°C for 30 min. The maximal activity was exhibited at temperature of 80°C and to a pH 12. The enzyme activity and stability was enhanced in presence of the Ca2+.

Fruits and vegetables are important part of the diet of most humans. They are highly nutritive, a... more Fruits and vegetables are important part of the diet of most humans. They are highly nutritive, and constitute an important source of minerals and vitamins. However the widely consumed fruits and vegetable are rich in phytic acid that causes reduction in the absorption and bioavailability of nutrients and minerals. The use of probiotic bacteria such as phytic acid degrading lactic acid bacteria (LAB) in the diet could help to prevent the chelation of mineral by phytates. Therefore the aim of this study was to screen, select and characterise phytate degrading LAB isolated from fruits and vegetables. LAB was isolated from 106 fruits and vegetables samples collected in Buea and Limbe using pour plating method on de Man Rogosa and Sharpe (MRS) agar. The isolates were characterised using the catalase test, Gram staining and the API 50 CHL BioMerieux kit. The phytate degrading activity of LAB was carried out qualitatively on modified MRS agar by point inoculation and the phytase activity was quantified in broth by spectrophotometric method. Thirty three LAB isolates were isolated. In which Twenty one produced a clear zone of hydrolysis on modified MRS agar demonstrating their phytate degrading potentials. Lactobacillus rhamnosus and Lactobacillus plantarum showed the highest phytate degradation both qualitatively and quantitatively, producing the highest amounts of the enzyme phytase. Both isolates also had a good tolerance to bile and acidic conditions, there by showing their ability to survive in the gastrointestinal track. This work shows a new perspective on the phytate degrading power of LAB thereby highlighting the ability of LAB to decrease malnutrition due to mineral deficiency.

The commonly used probiotic bacteria are lactic acid bacteria (LAB) from the gastroint... more The commonly used probiotic bacteria are lactic acid bacteria (LAB) from the gastrointestinal tract. However, other LAB from exogenous origin having similar functional properties may also confer health benefit to the host. Palm wine has been described as a rich source of LAB. But very few studies have investigated their probiotic potential. Twenty LAB were isolated from palm wine collected in the South West Region of Cameroon by pour plate method on MRS agar. These isolates were assessed in vitro for their potential to inhibit the growth of some foodborne pathogens, mainly Salmonella sp. and Escherichia coli using disc diffusion method. Acid and bile tolerance were evaluated by measuring the survival rate of LAB after incubation at pH range from 1.0 to 3.0 and various bile salt concentrations (0.15-0.30%). Only five isolates were selected based on their potential to inhibit food borne pathogens tested and their tolerance in acid and bile. They were identified using API kit 50 CHL BioMerieux as strains of Lactobacillus pentosus, Lactobacillus plantarumand Lactobacillus brevis. All these strains showed antimicrobial activity against strains of Salmonella sp. and E. coli with diameters of inhibition varying from 12 to 20 mm. Only L. pentosus and L. brevis1 tolerated pH 3.0 (acidic condition of interest) with survival rates of 55 and 69% respectively, while all survived in bile with survival rates above 60%.

nteractions occurring between Saccharomyces cerevisiae and two thermostable α-amylase producing s... more nteractions occurring between Saccharomyces cerevisiae and two thermostable α-amylase producing strains (Bacillus amyloliquefaciens 04BBA15 and Lactobacillus fermentum 04BBA19) were analyzed by comparing their growth patterns obtained in isolation with those obtained in mixture. The difference between the patterns was assessed using analysis of variance (ANOVA) in order to measure how much the growth of an organism was affected by other. The results showed two types of interactions in mixed culture; commensalism between S. cerevisiae and B. amyloliquefaciens 04BBA15 and mutualism between S. cerevisiae and L. fermentum 04BBA19. In mixed culture, the α-amylase production increased significantly compared to that observed in monoculture (P < 0.05). Response surface optimization of fermentation parameters in mixed cultures (initial yeast to bacteria ratio 1.125, temperature 33.5 °C, pH 5.5) resulted in about 1.8 fold higher enzyme production than that observed in the unoptimized fermentation.
Keywords

Microbial interactions; Thermostable amylases; Statistical optimization

One hundred and nineteen amylases producing strains (29 yeasts and 90 bacteria) were isolated fro... more One hundred and nineteen amylases producing strains (29 yeasts and 90 bacteria) were isolated from some Cameroonian soils contaminated by starchy residues and screened for thermostable amylases production. Phenotypic characterization of these amylases producing strains revealed the prominence of ascomycetous yeasts and two kinds of bacteria; the aerobic endospore forming dominated by Bacillus spp and aero-anaerobic non spore forming bacteria dominated by lactic acid bacteria of Lactobacillus spp. Among yeasts, one designated 04LBA3 produced high title of very high thermostable amylase. It was able to provoke starch hydrolysis halo of 33.7± ± ± ±1.5 mm on starch agar plate, and produced 80 ± ± ± ±0.5 U/ml of amylase in starch broth after 48 h of incubation at 30°C. Concerning amylases producing bacteria, two isolates designated 04BBA15 and 04BBA19 showed very high amylolytic power, the values were 55.0± ± ± ±3.2 mm and 45.3± ± ± ±1.5 mm of starch hydrolysis halo respectively for 04BBA15 and 04BBA19. Amylase production in starch broth were 131.0 and 107.7 U/ml respectively for 04BBA15 and 04BBA19 after 48 h of incubation at 40°C, on the other hand, their crude amylase extract remained 100% of original activity after been heated at 80°C for 30 min. The strain 04LBA3, 04BBA15, 04BBA19 were respectively identified as strain of Schwanniomyces alluvius, Bacillus amyloliquefaciens and Lactobacillus fermentum. Cluster analysis on the basis of amylolytic activity and thermostability of crude amylase extract showed similarities between strains of same geographic origin, this observation allows us to suggest that amylase activity and thermostabilty can serve as indicators for micro-organisms traceability.

Les substrats amylacés sont les plus abondants après la cellulose, ils constituent des sources im... more Les substrats amylacés sont les plus abondants après la cellulose, ils constituent des sources importantes de matières premières valorisables, en particulier dans la production d'éthanol. Les levures de distillerie communément utilisées étant dépourvues de l'activité amylasique, la production d'éthanol à partir de l'amidon nécessite un prétraitement d'hydrolyse généralement onéreux à cause du coût élevé des enzymes amylolytiques utilisées et la dépense énergétique liée à l'hydrolyse. Afin d'améliorer le rendement de la production d'éthanol à partir de matières premières amylacées, une souche de levure amylolytique (Schwanniomyces sp) isolée du sol a été testée en culture pure et en co-culture avec une souche commerciale de Saccharomyces cerevisiae. En culture pure l'activité amylasique de la souche de Schwanniomyces sp dépend de la source d'amidon utilisée ; elle atteint 101,5 U/ml et 80,0U/ml respectivement dans les moûts constitués de 8% (p/v) de farine de maïs et de manioc. Cette souche a été capable d'hydrolyser l'amidon toute seule et de convertir les sucres simples obtenus jusqu'au stade de l'éthanol. La co-culture de cette souche avec S cerevisiae augmente le rendement de la fermentation éthanolique qui atteint 96,4%. Ce rendement est comparable à celui obtenu au cours du procédé classique.

Fruits and vegetables are important part of the diet of most humans. They are highly nutritive, a... more Fruits and vegetables are important part of the diet of most humans. They are highly nutritive, and constitute an important source of minerals and vitamins. However the widely consumed fruits and vegetable are rich in phytic acid that causes reduction in the absorption and bioavailability of nutrients and minerals. The use of probiotic bacteria such as phytic acid degrading lactic acid bacteria (LAB) in the diet could help to prevent the chelation of mineral by phytates. Therefore the aim of this study was to screen, select and characterise phytate degrading LAB isolated from fruits and vegetables. LAB was isolated from 106 fruits and vegetables samples collected in Buea and Limbe using pour plating method on de Man Rogosa and Sharpe (MRS) agar. The isolates were characterised using the catalase test, Gram staining and the API 50 CHL BioMerieux kit. The phytate degrading activity of LAB was carried out qualitatively on modified MRS agar by point inoculation and the phytase activity was quantified in broth by spectrophotometric method. Thirty three LAB isolates were isolated. In which Twenty one produced a clear zone of hydrolysis on modified MRS agar demonstrating their phytate degrading potentials. Lactobacillus rhamnosus and Lactobacillus plantarum showed the highest phytate degradation both qualitatively and quantitatively, producing the highest amounts of the enzyme phytase. Both isolates also had a good tolerance to bile and acidic conditions, there by showing their ability to survive in the gastrointestinal track. This work shows a new perspective on the phytate degrading power of LAB thereby highlighting the ability of LAB to decrease malnutrition due to mineral deficiency.

Microbial interactions; Thermostable amylases; Statistical optimization