Optimization of process parameters for maximum poly(-beta-)hydroxybutyrate (PHB) production by Bacillus thuringiensis...

Area of Science:

• Microbiology
• Biotechnology

Background:

• Poly-beta-hydroxybutyrate (PHB) is a biodegradable polymer with diverse applications.
• Efficient microbial production of PHB is crucial for its commercial viability.

Purpose of the Study:

• To screen and identify a novel Bacillus strain capable of accumulating PHB.
• To optimize media parameters for enhanced PHB production by the identified strain.

Main Methods:

• Isolation and identification of a PHB-accumulating bacterium from soil using 16S rDNA sequencing.
• Optimization of growth conditions, including biphasic cultivation and nutrient limitation (nitrogen deficiency).
• Analysis of PHB accumulation over time and characterization of the extracted polymer via UV spectroscopy.

Main Results:

• A Gram-positive bacterium, identified as Bacillus thuringiensis IAM 12077, was isolated and confirmed to accumulate PHB.
• Biphasic growth, transitioning from nutrient broth to nitrogen-deficient medium, significantly enhanced cell dry weight and PHB accumulation (from 24% to 43.37%).
• Maximum PHB production (1.2 g/l) and accumulation occurred at 24 hours in nitrogen-deficient medium, coinciding with the stationary growth phase.

Conclusions:

• Bacillus thuringiensis IAM 12077 is a promising strain for poly-beta-hydroxybutyrate (PHB) production.
• Nutrient limitation, specifically nitrogen deficiency and biphasic cultivation, are key factors for maximizing PHB yield.
• The study provides a foundation for further research into large-scale PHB biosynthesis using this optimized microbial system.