ABSTRACT
Five acid forming bacteria, SK3-3, SK3-6B, SK3-7B, SK13-3 and PL20-4S were isolated from soils collected in Samut Songkhram and Phitsanulok provinces. All isolates were Gram-positive, anaerobic, spore-forming, rodshaped bacteria. The isolates were screened for their end product fermentation and were identified based on their phenotypic characteristics and 16S rRNA gene sequence analyses. They were belonged to the genus Clostridium and were closely related to Clostridium butyricum DSM 10702T (99.7-100%) and Clostridium saccharoperbutylacetonicum N1-4T (98.0-98.2%) based on 16S rRNA gene sequence similarity. All 5 isolates were identified as Clostridium butyricum. They produced 4.51-8.90 g/L (19.40-54.82% yield) of L-lactic acid with 0.06-0.12 g/L/h productivity, 6.15-7.52 g/L of acetic acid and 24.32-29.67 g/L of ethanol as the end product fermentation.