Improvement of Lactobacillus brevis NM101-1 grown on sugarcane molasses for mannitol, lactic and acetic acid production

The conversion of sugarcane molasses for the production of lactic acid, acetic acid, and mannitol was enhanced by subjecting Lactobacillus brevis NM101-1 wild strain to various doses of gamma irradiation. Four mutants (LM-1-LM-4) obtained at gamma ray doses of 30, 60, 90, and 120 Gy produced higher levels of lactic acid, acetic acid, and mannitol than the wild-type. Among all the mutants tested, LM-3 strain showed the highest mannitol and acetic acid production which reached 198.95 and 96.86 g/l, respectively. On the other hand, mutant LM-1strain exhibited the best performance with respect to lactic acid production (143.73 g/l). Random amplified polymorphic DNA polymerase chain reaction technique (RAPD-PCR) using three primers (RP, R5, and M13) was used in order to detect the variation in DNA profile in response to gamma irradiation treatments. RAPD analysis indicated the appearance and disappearance of DNA polymorphic bands at different gamma ray doses. The results showed the potential of these mutants to be potential candidates for economical production of mannitol, lactic and acetic acids from molasses on a commercial scale.