Lactic acid production by Pediococcus pentosaceus HLV1 from banana crop residue: an economic and renewable resource

Utilization of renewable bioresources for the production of industrial products such as biofuels and biochemicals is one of the best alternative strategies for sustainable development. Banana crop residue (BCR) is one of such renewable substrates that are readily available widely. In the current work, the production of lactic acid (LA) from BCR by recently isolated Pediococcus pentosaceus HLV1 was studied. We found that the dried BCR had 40.6 ± 4.1%, 21.0 ± 2.0%, and 17.4 ± 1.5% of cellulose, hemicellulose, and lignin respectively. Pretreatment with 1% sulfuric acid removed 60% of hemicellulose and 54% of lignin. In the pretreated BCR, cellulose content was increased to 61.5 ± 2.0% from 40.6 ± 4.1% of native BCR. Enzymatic saccharification with celluclast 1.5 L enzyme yielded 0.58 and 0.16 g/g sugars from pretreated and untreated BCR biomass, respectively. After 72 h of BCR Hydrolysate fermentation, 56.5 g/l of lactic acid was produced with a yield of 1.10 g LA/g substrate and with a productivity of 0.78 g/l/h. Pretreatment by-products such as HMF (5-hydroxymethylfurfural), furfural, and polyphenols were analyzed and studied their effect on cell growth and LA production along with their biotransformation. After the fermentation, the concentration of HMF (5-hydroxymethylfurfural) and furfural decreased significantly from 1.9 to 0.56 g/l and from 0.95 to 0.17 g/l, respectively. The noted polyphenols, vanillin, and ferulic acid concentrations were decreased to 0.16 mg/ml and 0.18 g/l from 0.3 mg/ml and 0.38 mg/ml respectively. For the first time, degradation of phenolic compounds and furfurals was studied with BCR and observed significant biotransformation by the newly P. pentosaceus HLV1. BCR will be a new and potential substrate for the synthesis of industrial products through fermentation technology. Graphical abstract: [Figure not available: see fulltext.]