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ABSTRACT
The marine bacterial isolate MS7 grown in treated shrimp waste (TSW) showed the most potent degrading activity (Au = 12.8) upon swollen chitin plates. This isolate was submitted to the phenotypic characterization through morphological, physiological and biochemical tests and submitted to genotypic characterization through 16S rDNA technique. Sequence of the isolate MS7 was affiliated according to their 16S rDNA to the genus Alcaligenes. The isolate MS7 showed 88% sequence homology to Alcaligenes faecalis. The optimum conditions for the highest chitinase activity secreted by A. feacalis MS7 were detected as 37°C (Au = 13.7 and U/ml = 10.1), pH 7 (Au = 12.1 and U/ml = 9.3) and 72 h incubation period (Au= 12.6 and U/ml = 9.6). Seven factors were examined as independent variables affecting the production of reducing sugars (mainly N-acetyl-D-glucoseamine; GlcNAc) from TSW by A. feacalis MS7 using Plackett-Burman experimental design. The main effect data as well as the t-test results suggested that the yeast extract is the most effective variable that controlled the reducing sugar value by A. feacalis MS7. The predicted near optimum and far from optimum levels of the independent variables were examined and compared to the basal condition settings. The applied near optimum condition resulted in 0.68 g/l reducing sugar, while the basal medium formulation recorded 0.24 g/l reducing sugar. On the other hand, the condition predicted to be far from optimal did not record any activity for reducing sugar production. Fermentation step included Candida albicans ATCC 14053 to ferment GlcNAc into bioethanol. It produced 2.6% bioethanol from 25 g/l sugar solution. The Plackett-Burman design was applied again to optimize the bioethanol production by C. albicans ATCC 14053 at certain variables and with higher sugar solution (40 g/l). The main effect data as well as the t-test results suggested that the higher levels of the GlcNAc solution, the incubation period and yeast extract were the most effective variables that controlled the bioethanol production. The applied near optimum condition, resulted in approximately 7.9% bioethanol from GlcNAc with increasing 1.46 folds than the basal medium formulation that recorded 5.4% bioethanol. On the other hand, the fermentation condition predicted to be far from-optimum recorded no activity in the fermentation of GlcNAc. However, these results support the predictions expected from the...