Composite organic waste was assessed for its physical, chemical and microbial suitability to serve as a substrate for the fermentative production of lactic acid. The biowaste studied was highly acidic (pH 4.3) and had high organic carbon content (45%). A clone library identified 90% of the bacterial community were lactic acid bacteria, mainly represented by Lactobacilli (70%). Cultivation using semiselective media identified Lactobacillus plantarum, Lactobacillus brevis and their closest relatives as the dominating taxa. PCR-DGGE using general bacterial and lactic acid bacterial specific primers resulted in little heterogeneity of microbial community. These data indicate that biowaste is a preferred habitat of lactic acid bacteria, suggesting that the unsterilized biowaste and its natural flora could be used in a fermentation process for lactic acid production. Such kind of biowaste application could be an alternative for current substrates and provide a modern, efficient and environmental friendly waste treatment technology. (c) 2013 Elsevier Ltd. All rights reserved.