Antimicrobial activity of extracellular liquid obtained from molasses fermentation by Nocardia sp strain V1

Abstract

Molasses is one of agricultural wastes that could be utilized as a substrate for microbial fermentation. The utilization of molasses as a fermentation medium is expected to increase its added value. In this study, molasses served as a carbon source for bolstering the growth and the production of extracellular liquid having antimicrobial activity produced by Nocardia sp strain V1. The six types of fermentation media containing three carbon sources namely molasses, molasses-starch, and molasses-glucose were prepared; wherein molasses used were the ones with and without the pre-treatment using K4Fe(CN)6.3H2O. This chemical was used to precipitate heavy metals and other substances in molasses that might inhibit the growth of the bacteria. The antimicrobial activity of extracellular liquid produced by Nocardia sp strain V1 was evaluated against 10 microbes isolated from infected strawberries and pseudostem of banana plant. The result showed that the antimicrobial activities were demonstrated by the extracellular liquid derived from the bacteria grown in the media containing pre-treated molasses-starch (M2 medium), pre-treated molasses-glucose (M3 medium), and glucose-starch (synthetic medium) as the carbon sources. The extracellular liquid from those fermented media was able to inhibit 2 microbes from a total of 10 microbes identified as Rhodotorula sp and Fusarium graminearum with the inhibition diameter ranged from 10-21 mm.