Isolation, Characterization, and Effect on Biofilm Formation of Bacteriocin Produced by Lactococcus lactis F01 Isolated from Cyprinus carpio and Application for Biopreservation of Fish Sausage.

The aim of this work was the screening of bacteriocin-producing LABs isolated from fish, the selection of promising/prominent strain(s), the characterization of the bacteriocin produced, and the evaluation of its potential to be used as biopreservative(s). Amplification and sequencing of the 16S rRNA gene of the bacteriocin-producing strain was performed. Then a partial purification of the produced bacteriocin, using a combination of ammonium sulfate and chloroform-methanol precipitation, was done. Its molecular weight was determined by SDS-PAGE. In addition, the action spectrum, the hemolysis test, and its ability to inhibit biofilm formation were analyzed. A total of 88 isolates of lactic acid bacteria (LAB) including one bacteriocin producer, which was identified as Lactococcus lactis F01, were collected. The bacteriocin was partially purified with an estimated yield of 40%. Regarding the SDS-PAGE profile, the secreted bacteriocin has molecular weight of about 3.5 kDa and was identified as class I bacteriocin. The antimicrobial test showed that the bacteriocin inhibits pathogenic and/or spoilage bacteria, 10 Gram-positive and 16 Gram-negative bacterial species. Moreover, it can inhibit biofilm formation from 1.3% (Escherichia coli) to 63.92% (Pseudomonas aeruginosa ATCC15692) depending on the strain. The hemolytic activity of novel bacteriocin was observed at the concentration of 10 µg/ml of bacteriocin crude extract, which was 0.7 ± 0.0029%. In addition, it exhibited good thermal and pH stability with retained antibacterial activity of 85.25% after treatment at 121°C for 20 min, as well as at a pH range between 2.0 and 10.0. Moreover, this bacteriocin showed the ability to inhibit the growth of bacterial culture load in fish sausage stored at 8°C for 28 days. Considering the results obtained, bacteriocin could be potentially exploited as an alternative to chemical preservatives or as a substitute for antibiotics.

Technological characterisation and probiotic traits of yeasts isolated from Sha'a, a Cameroonian maize-based traditional fermented beverage.

The current trend in starter selection is to combine both technological and probiotic properties to standardise and make functional artisanal fermented beverages such as Sha'a whose properties are very variable due to the lack of a known starter. The objective of this work was to study technological and probiotic properties of yeasts isolated from Sha'a sold in Bamenda, Bafoussam, Bonabérie, Dschang, Foumbot, Mbouda and Njombé (Cameroon). The isolated yeasts were studied for their ability to produce CO2 from glucose, to grow in the presence of 8% ethanol, 20% glucose and pH 3, to assimilate maltose and to produce ethanol. Then, the survival of the pre-selected isolates was assessed in simulated gastric (pH 2 and 3) and intestinal juices, followed by self-aggregation, co-aggregation, hydrophobicity, haemolysin, gelatinase, biogenic amine production, antibiotic and antifungal susceptibility, bile salt hydrolase and antiradical activity. The selected isolates were identified by sequencing the 5.8S/28S rRNA gene. From the 98 isolates obtained, 66 produced CO2 from glucose and 16 were then selected for their ability to grow in the presence of 8% ethanol, 20% glucose, pH 3 and maltose. The overall survival of isolates ranged from 4.12 ± 1.63 to 104.25 ± 0.19% (LT16) and from 0.56 ± 0.20 to 96.74 ± 1.60% (LT66) at pH 3 and pH 2 respectively. All of them have remarkable surface hydrophobicity properties. Based on principal component analysis, 5 isolates were selected as the best. However, only 3 of them, LT16 (the most promising), LT25 identified as Saccharomyces cerevisiae and LT80 as Nakaseomyces delphensis, do not produce a virulence factor. The latter can deconjugate bile salts with a maximum percentage of 60.54 ± 0.12% (LT16) and the highest inhibition of DPPH° radicals was 55.94 ± 1.14% (LT25). In summary, the yeast flora of Sha'a contains yeasts capable of fermenting and producing ethanol while producing bioactive compounds that would benefit the consumer.

Effect of boiling and roasting on the physicochemical properties of Djansang seeds (Ricinodendron heudelotii).

This study was aimed at determining the effect of boiling and roasting on physicochemical properties of Djansang seeds. Dried Djansang seeds were divided into three groups: one group was boiled for 5, 10, and 15 min; another group was traditionally roasted for 5, 10, and 15 min, and the last group was left unprocessed and served as the control. Polyphenols were extracted from the processed seeds using the maceration method, and their content and antioxidant activity were evaluated. Oils were extracted from the dried seeds by Maceration method, and the quality was analyzed by determining their peroxide value (PV), thiobarbituric acid value (TBA), iodine value (IV), and acid value (AV). The changes in proximate composition and mineral content of the processed samples were also evaluated using standard methods. Results showed that traditional roasting significantly decreases (p < .05) the polyphenol content and antioxidant activity of Djansang seeds as compared to boiling. The analysis of oil showed that traditional roasting and boiling significantly reduce the quality of Djansang seed oil (PV: 10.85-38.49 meq O2/kg; TBA: 1.80-3.20 ppm; AV: 0.28%-0.82%; and IV: 104.27-98.11 g I2/g for roasted samples, and PV: 10.85-27.52meq O2/kg; TBA: 1.45-2.28 ppm; AV: 0.56%-0.96%; and IV: 105.87-102.96 g I2/g for boiled samples) compared to the control (PV: 9.96 meq O2/kg; TBA: 1.01 ppm; AV: 0.11%; and IV: 104.83 g I2/g) and that traditionally roasted samples were the most affected. The proximate and mineral composition of Djansang was also affected during processing. Boiling for 5 and 10 min (BNS 5 min and 10 min) and traditional roasting for 5 min (TRNS 5 min) appear to be the best processing methods of Djansang for production of Djansang-based foods like Djansang sauce.

Bacteriocinogenic Lactococcus lactis subsp. lactis 3MT isolated from freshwater Nile Tilapia: isolation, safety traits, bacteriocin characterisation, and application for biopreservation in fish pâté.

This work was aimed to screen bacteriocin-producing LAB from freshwater fish, select a prominent strain and evaluate its safety, characterise the bacteriocin produced, and evaluate its potential to be used as biopreservatives. Isolate 3MT showed the ability to produce bacteriocin-like substances and was identified as Lactococcus lactis subsp. lactis. This strain proved to be free from virulence factors as well as biogenic amine production and antibiotic resistance patterns. The bacteriocin produced displayed high resistance to heat, pH, detergents, and its partial purification led to a 4.35-fold increase in specific activity. Moreover, this bacteriocin showed the ability to inhibit the growth of Vibrio sp. 1T1 in fish pâté stored at 10 °C for 20 days, without altering its sensory properties. The bacteriocin can be used successfully as a preservative to improve the hygienic quality and enhance the shelf life of fish paté in particular and food products in general. Lactococcus lactis subsp. lactis strain 3MT can also be safely used as a protective culture.

Water supply, sanitation and health risks in Douala 5 municipality, Cameroon.

BACKGROUND: In the poor zones of sub-Saharan Africa, the conventional drinking water network is very weak. The populations use alternative groundwater sources which are wells and springs. However, because of urbanization, the groundwater sources are degrading gradually making pure, safe, healthy and odourless drinking water a matter of deep concern. There are many pollutants in groundwater due to seepage of organic and inorganic pollutants, heavy metals as well as microbiological contamination. This study was carried out in October 2012 and aimed to analyze the practices and behaviors of populations related to water supply that may constitute potential risks of microbiological contamination and emergence of waterborne diseases. METHOD: This study was carried out on a sample of 285 households, distributed in twelve principal quarters of the Douala V municipality in Cameroon. After data collection through the questionnaires, the selection of vulnerable quarters was done by the tabulation of some specific results on the questionnaire. The microbiological analysis was carried out using an innovative rapid test called "Micro Biological Survey (MBS)" that has been developed and patented by MBS srl, a recent spin-off of the University of Roma Tre. RESULT: We found out that 42.30% of households used water from drilled wells (forages), 33.80% from Cameroon National Water Company (CDE) distribution network, 9.50% from spring, and 9.40% used other source of water such as buying industrial mineral water. However, it should be noted that, as dangerous as it may be, wells ("puits" in French) water is used as permanent source of drinking water by 5% of households. In general, 63.2% of households affirmed not to have benefited the fitting of public water point. Moreover, among the quarters were the households affirmed to have benefited from the development of a public water point, 52.5% of these water point were no longer functional. From the obtained data we have assessed that 83% of wells analyzed are faecally contaminated and all the forages analyzed (100%) are not contaminated. The most affected people by water-related diseases are children under 5 years (43%). CONCLUSION: We highly recommend the City Council of Douala V to restrict the use of the contaminated wells and provide alternative water sources such as forages for public use and to ensure that microbiological quality of the new and already existing water sources is controlled regularly by the Technical Service.

Condom perception and prevention of HIV/AIDS infection in Cameroon: appraisal of knowledge, attitudes and practices among level one students of the University of Dschang.

BACKGROUND: With the decreasing HIV epidemiology in Cameroon (5.5% in 2004 to 4.3% in 2011), HIV/AIDS remains a major public health concern, affecting mostly the sexually active population, among which the young University students represent an important target. Since sexual intercourses represent about 90% of HIV transmission, understanding the sexual behaviors of youth could relevantly optimize the design of HIV prevention strategies, through updated and adapted communication strategies for healthy sexual behavioral changes. METHODOLOGY: A qualitative, descriptive and cross-sectional study was conducted in November 2010, among 518 newly registered students in the various faculties of the University of Dschang, Cameroon. In order to evaluate Knowledge, Attitudes and Practices (KAP) toward HIV/AIDS prevention among the study participants, a structured questionnaire was administered to each participant, on the basic knowledge about HIV/AIDS and condoms. Data analysis was performed using Epi Info version 3.5.0 software. RESULTS: The mean age of participants was 20 years, with a slight female predominance (52%). 98.6% of students voted familiar with the theme "condom", with 88.9% giving a satisfactory definition. However, 41.1% do not know the appropriate transmission route of HIV, while 5.4% do not master the correct use of condom; with up to 75.7% being aware of the female condom existence. Although 97.8% of students consider the proper use of condoms as an effective HIV preventive tool, up to 34.5% of them fail to use condoms during sexual intercourses and 69% were not in favor of the use of female condom, mainly due to a decreasing sexual pleasure. CONCLUSION: Despite the existing sensitization campaigns, the perception of condoms is still very poor among young Cameroonian academics; with the non-systematic use of condoms being the major setback. The lack of familiarity to female condom, both among female and male, would also be a contributing drawback. These major sexual behavioral risk factors to HIV infection appear as key points to address during the campaigns to ensure owning of healthy sexual habits, a leading component to reduce HIV incidence among young Cameroonian/Africans.

Antimicrobial and Safety Properties of Lactobacilli Isolated from two Cameroonian Traditional Fermented Foods.

Twenty-one Lactobacillus isolates from "Sha'a" (a maize - based fermented beverage) and "Kossam" (traditionally fermented cow milk) were selected in accordance with their antagonistic activities and tested for their bacteriocinogenic potential as well as safety properties. These isolates were preliminarily identified as Lactobacillus plantarum (62%), Lactobacillus rhamnosus (24%), Lactobacillus fermentum (10%) and Lactobacillus coprophilus (4%) based on phenotypic characteristics and rep-PCR genomic fingerprinting. Twelve (57.1%) out of the 21 strains tested were found to be bacteriocin producers, as revealed by the sensitivity of their antimicrobial substances to proteolytic enzymes (Trypsin, Proteinase K) and inhibition of other Lactobacillus spp. These bacteriocinogenic strains showed no positive haemolytic and gelatinase activities and proved to be sensitive to penicillin G, ampicillin, tetracycline, erythromycin, amoxicillin, chloramphenicol, co-trimoxazole and doxycyclin, but resistant to ciprofloxacin and gentamicin. The bacteriocins showed a broad inhibitory activity against Gram-positive and Gram-negative pathogenic bacteria, several of which are classified as especially dangerous by the World Health Organization, as well as Multidrug-resistant strains. These include Staphylococcus aureus, Salmonella enterica subsp. enterica serovare Typhi, Bacillus cereus, Streptococcus mutans, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Shigella flexneri. These Lactobacillus strains are promising candidates for use as protective cultures in food fermentation.