Screening, Optimization, and Characterization of PHA from Exiguobacterium sp. under Different Carbon and pH Conditions
DOI:
https://doi.org/10.65761/jbs.2025.13Keywords:
Exiguobacterium sp.; Polyhydroxyalkanoates; PHA production; Cane molasses; FTIR spectroscopyAbstract
Background: Polyhydroxyalkanoates (PHAs) are biodegradable microbial polymers with considerable potential as environmentally friendly alternatives to conventional petroleum-based plastics.
Objective: The present study aimed to screen Exiguobacterium sp. and Klebsiella sp. for PHA production and optimize PHA accumulation under different carbon source concentrations and pH conditions.
Methods: The bacterial strains were screened using Nile blue and Sudan Black B staining. PHA production was evaluated using glucose, sodium gluconate, and pretreated cane molasses at 0.105% and 2.1% concentrations and pH values of 5, 7, and 8. Bacterial growth, biomass production, and PHA accumulation were monitored during cultivation. Extracted PHA was further characterized using Fourier-transform infrared (FTIR) spectroscopy.
Results: Exiguobacterium sp. exhibited stronger Nile blue fluorescence and more prominent Sudan Black B-positive intracellular inclusions than Klebsiella sp., indicating greater PHA-producing potential. PHA accumulation varied with carbon source, substrate concentration, pH, and incubation period. Higher carbon availability and near-neutral pH generally favored bacterial growth and PHA production. Pretreated molasses successfully supported bacterial growth and polymer synthesis, demonstrating its potential as a low-cost carbon substrate. FTIR analysis confirmed characteristic functional groups associated with PHA.
Conclusion: The findings indicate that Exiguobacterium sp. is a promising PHA-producing bacterium, while pretreated cane molasses represents a potential inexpensive substrate for sustainable microbial biopolymer production.
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