Screening of microorganisms producing lactic acid using glycerol as a sole carbon source

Abstract

Microorganisms which produce lactic acid by using glycerol as a sole carbon source were identified from various sources, 14 samples such as soil and waste water contaminated with crude glycerol from biodiesel production process, EM bio-extract samples etc. The microorganisms from these samples were selected by cultivated in crude glycerol as a sole carbon source and calcium carbonate. As the results, EM-bio-extract had the widest clear zone and the other samples had very narrow clear zone and some of them no clear zone. Therefore, the 18 microorganisms from EM bio-extract samples which had the most widest clear zone were continued to investigate growth rate and lactic acid production. The results showed that the EM383 was the most rapid growth and the EM335 had the widest clear zone as 17.07 mm. After that, the EM335, the EM383 and the EM335 mixed with the EM383 were cultivated in medium containing crude glycerol, 99% glycerol and 99.5% glycerol. It was found that the EM335 produced the highest amount of lactic acid as 84.76 µg/L when it was cultivated in medium containing crude glycerol as a sole carbon source.