Quantitative analyses of the bacterial microbiota of rearing environment, tilapia and common carp cultured in earthen ponds and inhibitory activity of its lactic acid bacteria on fish spoilage and pathogenic bacteria.

The present study aimed to evaluate the bacterial load of water, Nile Tilapia and common Carp intestines from earthen ponds, isolate lactic acid bacteria (LAB) and assess their antimicrobial activity against fish spoilage and pathogenic bacteria. Following enumeration and isolation of microorganisms the antimicrobial activity of the LAB isolates was evaluated. Taxonomic identification of selected antagonistic LAB strains was assessed, followed by partial characterisation of their antimicrobial metabolites. Results showed that high counts (>4 log c.f.u ml-1 or 8 log c.f.u g-1) of total aerobic bacteria were recorded in pond waters and fish intestines. The microbiota were also found to be dominated by Salmonella spp., Vibrio spp., Staphylococcus spp. and Escherichia coli. LAB isolates (5.60%) exhibited potent direct and extracellular antimicrobial activity against the host-derived and non host-derived spoilage and pathogenic bacteria. These antagonistic isolates were identified and Lactococcus lactis subsp. lactis was found as the predominant (42.85%) specie. The strains displayed the ability to produce lactic, acetic, butyric, propionic and valeric acids. Bacteriocin-like inhibitory substances with activity against Gram-positive and Gram-negative (Vibrio spp. and Pseudomonas aeruginosa) bacteria were produced by three L. lactis subsp. lactis strains. In this study, the LAB from the microbiota of fish and pond water showed potent antimicrobial activity against fish spoilage or pathogenic bacteria from the same host or ecological niche. The studied Cameroonian aquatic niche is an ideal source of antagonistic LAB that could be appropriate as new fish biopreservatives or disease control agents in aquaculture under tropical conditions in particular or worldwide in general.

Physicochemical properties, nutritional value, and antioxidant potential of jackfruit (Artocarpus heterophyllus) pulp and seeds from Cameroon eastern forests.

This work aimed to study the physicochemical, nutritional, and antioxidant characteristics of the pulp and seeds of the jackfruit collected in the East Cameroon region to reduce the malnutrition problems encountered in the said region. To achieve this work, we first administered a survey. We observed that 50 people from Bertoua knew the fruit among the 200 people surveyed. After that, the physicochemical characteristics and nutritional value of Artocarpus heterophyllus pulp and seeds from Bertoua were evaluated. Finally, the antioxidant compounds (total phenolic and flavonoid contents) and the antioxidant activities were evaluated through the DPPH free radical scavenging capacity, the ability to reduce ferric ions, and the hydroxyl radical scavenging ability using the aqueous, ethanolic, and hydro-ethanolic extracts of these samples (pulp and seeds). Results (means ± standard deviation) were obtained in triplicate and analyzed statistically by the analysis of variance (ANOVA) at the 0.05 probability level. The results revealed that the jackfruit pulp has a water content (89.85% ± 0.49) significantly higher than that of seeds (60.075% ± 0.12). The pH of jackfruit pulp (5 ± 0) is significantly lower than that of seeds (6 ± 0). Jackfruit pulp had a carbohydrate content (54.39% ± 0.47) significantly higher than that of seeds (49.01% ± 0.43). The protein content of jackfruit pulp (18.35% ± 0.04) is lower than that of the seeds (21.66% ± 0.31). For mineral content, the maximum contents of K (848 mg/100 g ± 10.34) and Na (69.53 mg/100 g ± 0) were identified in the jackfruit pulp while those of Ca (132 mg/100 g ± 9.42), Mg (43.73 mg/100 g ± 9.12), and P (101.51 mg/100 g ± 4.02) were found in the seeds. However, all extracts possessed both antioxidant compounds (phenols and flavonoids) and antioxidant activities. In conclusion, the jackfruit appears to be a fruit that can improve the nutritional status of the populations of eastern Cameroon.