Anti-bacterial profile of some beers and their effect on some selected pathogens

The investigation of the therapeutic properties of some beers, allow us to study their anti-bacterial profile against food born diseases caused by bacteria such as Escherichia coli, Salmonella typhimurium, Staphilococcus aureus, Bacillus cereus, Bacillus anthracis and Bacillus subtilis. The results obtained show that beers B2 and B3 had no anti-bacterial activity on the tested bacteria, whereas, beer B1 had bactericidal activity on gram positive and gram negative bacteria. The anti-spore activity of beer B1 on B. anthracis, B. cereus and B. subtilis exhibited a microcycle (sporulationgermination-sporulation), which could permit the application of soft preservation methods during the first 5 h for B. cereus and B. subtilis and during the first 10 h for B. anthracis. Finally, the results seem to confirm some popular practices. The beer B1 presents some potentialities for the treatment of gastro-enteritis.Keywords: Food contaminations, beer, anti-bacterial substance, gastro-enteritisAfrican Journal of Biotechnology Vol. 9(36), pp. 5938-5945, 6 September, 201

Comparison of bacterial communities of tilapia fish from Cameroon and Vietnam using PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis)

Fishes in general and tilapia in particular are traded all over the world. However, it is difficult to find out their exact geographical location. One of the techniques used in the traceability of fish and its byproductsconsist in analysing in a global way the whole viable and non viable bacterial communities. For this purpose, the molecular technique employing the bacterial 16S DNA banding profiles generated by PCR-DGGE (polymerase chain reaction-Denaturing gradient gel electrophoresis) was used to evaluate the differences between the bacterial profiles of fishes from Vietnam (An Giang, south province) and those of Cameroon (Yagoua, Maga, Lagdo). The different PCR-DGGE 16S rDNA banding profiles obtained were analysed and results showed that there were specific bands for each geographical location though some bands common to Cameroon and Vietnam were observed. Thismethod could be used as a rapid analytical traceability tool for fish products and could be considered as a provider of a unique biological bar code

Influence of technological treatments on bacterial communities in tilapia (Oreochromis niloticus) as determined by 16S rDNA fingerprinting using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)

Food quality and safety are major concern among consumers throughout the world in the context of globalization. Hence, the origin and the history of a food item are of prime interest when food quality is questioned. Precise determination of contamination source relies on the use of efficient and reliable methods. This study was carried out to assess the microbial ecology of fish upon technological treatments using 16S rDNA polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting. Samples of tilapia from Montpellier (South-east of France) and Yagoua (far north of Cameroon) were used for this purpose. The technological treatments applied on fillets were marinade, drying, smoking and deep-freezing. When the 16S rDNA profiles were analysed by multivariate analysis, distinct microbial communities were detected. The band profiles of fish bacteria after each treatment were different and specific. Technological treatments applied on fillets from Montpellier did not have an effect on the biological markers present on the fillets. These bands could be used as specific markers for this region. One of the treatments, the marinade applied on the samples of Yagoua induced the disappearance of some bands on the DGGE profile. In spite of treatment applied on samples, it is possible to recover the geographical origin by using DNA of the bacterial community in fish even if it was treated.Keywords: Traceability, tilapia, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), bacterial community, technological treatment

Antiradical potential and antifungal activities of essential oils of the leaves of Citrus latifolia against Phaeoramularia angolensis

Investigations were conducted to determine the chemical composition, antiradical and antifungal activities of the essential oil extracted from the fresh leaves of Citrus latifolia var. Tahiti from Cameroonagainst Phaeoramularia angolensis. The essential oil obtained by hydrodistillation was analysed by GC and GC/MS. The disc diffusion method was used to evaluate the zone of fungal growth inhibition atvarious concentrations of the oil while the antiradical activity of the oil was studied by the DPPH (diphenyl picryl hydrazyl) method. The chemical analysis revealed 26 components among whichlimonene (45.76%), geranial (13.12%) and neral (10.35%) were the main components. The antiradical activity of C. latifolia essential oil (SC50 = 9.93 g/l) was less than that of butylated hydroxyl toluene (BHT) which was used as the reference compound (SC50 = 7.02 x 10-3 g/l). After 40 days of incubation on oil – supplemented medium, the growth of P. angolensis was totally inhibited by 1600 mg/l of C. latifolia oil. Results obtained in the present study indicate the possibility of exploiting C. latifolia var Tahiti essential oil to combat P. angolensis which is responsible for heavy losses of Citrus fruits harvests