Isolation and Evaluation of Extracellular Enzyme-producing Endophytic Bacteria from Curcuma caesia Roxb.
TL;DR
The bacterial endophytes associated with Curcuma caesia possess substantial extracellular enzyme-producing potential and their potential for agricultural, industrial, and biotechnological applications is assessed.
Abstract
Aims: The present study aimed to isolate, identify, and evaluate extracellular enzyme-producing bacterial endophytes from the rhizomes of Curcuma caesia Roxb. and to assess their potential for biotechnological applications. Study Design: An experimental, laboratory-based study. Place and Duration of Study: Department of Biotechnology, Dr B. R. Ambedkar University, Etcherla, Andhra Pradesh, India, from June to May 2025. Methodology: Endophytic bacteria were isolated from surface-sterilized rhizomes of Curcuma caesia and identified through morphological, biochemical, and 16S rRNA gene sequence analyses. The isolates were screened for extracellular amylase, protease, Cellulase, and lipase production using standard qualitative plate assays. Enzyme activities were quantified using the dinitrosalicylic acid (DNS) assay for amylase and cellulase, the Folin-Ciocalteu method for protease, and the olive oil emulsion titration assay for lipase. Results: Three bacterial endophytes were identified as Enterobacter hormaechei, Bacillus flexus, and Bacillus amyloliquefaciens. Enterobacter hormaechei exhibited the highest amylase (85 µg/mL; 0.000047 U/mL) and protease (70 µg/mL; 0.000039 U/mL) activities. In contrast, Bacillus amyloliquefaciens showed the highest cellulase (65 µg/mL; 0.000036 U/mL) and lipase (9.67 U/mL) activities, whereas Bacillus flexus displayed moderate enzyme production. The variation in enzyme activity among the isolates indicated their diverse hydrolytic capabilities and functional roles in the degradation of starch, proteins, cellulose, and lipids. Conclusion: The bacterial endophytes associated with Curcuma caesia possess substantial extracellular enzyme-producing potential. The superior amylase and protease activities of Enterobacter hormaechei and the enhanced cellulase and lipase production by Bacillus amyloliquefaciens indicate their potential for agricultural, industrial, and biotechnological applications. Further studies on enzyme purification, optimisation of production conditions, and large-scale production are recommended to evaluate their commercial potential.