Isolation and characterization of a new osmotolerant, non-virulent Klebsiella pneumoniae strain SAP for biosynthesis of succinic acid.

In the present study, isolation of anaerobic bacteria from 24 different eco-niches was carried out. A total number of 300 bacterial isolates, including 230 obligate and 70 facultative anaerobes were obtained using anaerobic techniques. All the isolates were initially screened for succinic acid production by Fluorescein test and TLC method. During screening, 10 isolates found to produce succinic acid were further examined by HPLC and then finally confirmed for succinic acid by LC-MS analysis. Amongst 10 isolates, isolate SAP, a facultative anaerobe isolated from buffalo rumen fluid, showed maximum yield of 2.1 g/l of succinic acid from 10 g of glucose in 24 hr under anaerobic condition. This isolate was identified as Klebsiella pneumoniae strain SAP by 16S rDNA sequence and signature sequence analysis. Mouse lethality test for the strain SAP showed LD50 value of 3.3 x 10(8) CFU/ml, which shows non-virulent nature of the strain. This strain may become a candidate strain for succinic acid production because of its osmotolerant nature and higher succinate:acetate ratio.