Identification and product optimization of amylolytic Rhodococcus opacus GAA 31.1 isolated from gut of Gryllotalpa africana

An attempt has been made to isolate potent amylase producing gut bacteria from Gryllotalpa africana. Out of 82 isolates, GAA 31.1 was selected as potent producer, having enzyme activity 9.6 ± 0.861 U/ml. The isolate GAA 31.1 was identified as Rhodococcus opacus following morphological, biochemical, physiological characterization and phylogenetic analysis through 16S rRNA gene sequencing. Fatty acid methyl ester profile of the isolate was also studied. The optimized physical cultural conditions for amylase production were found as incubation period 48 h, inoculum volume 2%, initial pH of the fermentation medium 7.0, temperature 38 °C and aeration at 150 rpm. Optimum nutrient conditions were determined as: supplementation of maltose 1.4% and sodium nitrate 1.4%. Surfactants SDS, EDTA, Tween 80 and Triton X-100 showed positive effect on enzyme production. Riboflavin (50 μg/ml) among the tested vitamins stimulated the production maximally. The isolate was also able to produce amylase using agro-industrial waste. This actinobacterium may be a potent candidate for amylase as it is capable of enhanced production (326.72 ± 6.081 U/ml) by utilizing agro-residues.