Cellulase from Halomonas elongata for biofuel application: enzymatic characterization and inhibition tolerance...

Halophilic bacteria are promising candidates for biofuel production because of their efficient cellulose degradation. Their cellulases exhibit high activity, even in the presence of inhibitors and under extreme conditions, making them ideal for biorefinery applications. In this study, we isolated a strain of Halomonas elongata (Kadal6) from decomposed cotton cloth on a Rameshwaram seashore. Morphological, biochemical, and 16S rRNA analyses revealed that Kadal6 was 99.93% similar to the cellulase-producing strain, H. elongata MH25661. The tolerance of the cellulase to inhibitors was assessed through molecular docking with a cellulase model of MH25661 generated by I-TASSER and experimentally using response surface methodology (RSM) with Kadal6. A molecular docking study indicated a high inhibition constant for ethanol, hydroxymethylfurfural (HMF), and furfural. Cellulase from H. elongata Kadal6 (CellHe) showed a maximum inhibition rate of 44.27% at 55 °C, 15% ethanol, and 6.5 g/L furfural and HMF. The enzyme retained 50% of its activity in the presence of these inhibitors, and remained unaffected at 1 g/L furfural and HMF, although inhibition occurred at 3 g/L. H. elongata cellulase demonstrated significant tolerance to inhibition both in vitro (RSM) and in silico, indicating its potential for biorefinery applications in harsh environments.