Characterization of moulds associated with processed garri stored for 40 days at ambient temperature in Makurdi, Nigeria

Characterization of moulds associated with processed white and yellow garri stored at ambient temperature for 40 days was investigated. The moulds isolated from white garri (%) were: Aspergillus spp 35.3, Penicillium spp 23.53, Fusarium spp 2.94, Mucor spp 17.65, Alternaria spp 5.88, Cladosporium sp 2.94 and Rhizopus 11.76%. For yellow garri: Aspergillus spp 37.04, Penicillium spp 23.53, Fusarium spp 7.41, Mucor spp 18.52, Rhizopus spp 14.81, Alternaria spp 0% Cladosporium sp. and Aspergillus spp had the highest frequency of occurrence in both white and yellow garri. Higher moulds species were isolated from white garri (34) compared to yellow (27) samples. The mean total fungal counts from the three hostels were 6.22 × 103, 7.22 × 104 and 9.67 × 105 CFUg-1 in white garri, and 3.56 × 103, 4.22 × 104 and 5.78 × 105 CFUg-1 in yellow garri. There were significant differences in total mean fungal counts in the various dilutions of white and yellow garri at p < 0.05. Results also revealed that the longer the storage time, the higher the pH and moisture content. Proper storage is recommended owing to the public health concern due to mycotoxins, food safety, shelf life and biostability of this product.Keywords: Garri, moulds, storage, pH, moisture contentAfrican Journal of Biotechnology, Vol. 13(5), pp. 673-677, 29 January, 201

Optimization of biosurfactant production by Bacillus thuringiensis c25 isolated from palm oil contaminated soil

Biosurfactants of microbial origin have wide applicability because of their surface-active potentials. Bacillus thuringiensis c25 isolated from palm oil contaminated soil was used in the production of biosurfactant and the product was screened using emulsification stability test (E24), drop-collapse, oil spreading, blood hemolysis and surface tension tests. The effects of incubation period, temperature, pH, and carbon source on biosurfactant production by B. thuringiensis c25 were investigated with a view to optimizing the production process. The biosurfactant produced was characterized using Fourier Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry. Initial assay showed emulsification index of 57.24 ± 0.25 %, oil displacement of 6.17 ± 0.21 mm and a positive drop-collapse test. Growth of B. thuringiensis at the optimal conditions of temperature 35 ºC, pH 7.0, glucose 10 g/L and yeast extract 1.5 g/L, reduced surface tension to 27.71 ± 0.88 mN/m and increased emulsification index to 84.78 ± 0.44%. Maximum biosurfactant production of 2.70 ± 0.04 g/L was obtained at 72 h. The characterization showed a lipopeptide biosurfactant type. Consequently, the B. thuringiensis of the present study is a good biosurfactant producer