Production, isolation, optimization, and characterization of microbial PHA from Bacillus australimaris

Area of Science:

• Microbiology
• Biotechnology
• Polymer Science

Background:

• Growing environmental pollution from nondegradable substances necessitates sustainable alternatives.
• Microbial polyesters, polyhydroxyalkanoates (PHAs), offer a biodegradable solution for bioplastics production.
• Microorganisms accumulate PHAs under nutrient-limited conditions.

Purpose of the Study:

• To screen soil microorganisms for polyhydroxyalkanoates (PHA) production.
• To optimize media parameters for enhanced PHA yield.
• To characterize the produced PHA and identify the producing organism.

Main Methods:

• Isolation and screening of soil microbes using Sudan black staining.
• Identification of promising strain GS-14 via sodium hypochlorite method.
• PHA quantification using a crotonic acid standard curve.
• Polymer characterization using FTIR, LC-MS, and DSC.
• Bacterial identification through 16S rRNA sequencing.
• Media optimization using Minitab software and statistical analysis.

Main Results:

• Seventeen soil isolates confirmed for PHA production.
• Strain GS-14 exhibited the highest PHA yield.
• FTIR confirmed PHA characteristic peaks (C=O stretch at 1732 cm⁻¹).
• LC-MS indicated an oligomeric species (641.6 g/mol); polymer MW estimated at 5,000–20,000 Da.
• DSC showed an exothermic peak at 174 °C, enabling crystallinity calculation.
• Bacillus australimaris identified as the PHA-producing organism (GS-14).

Conclusions:

• Bacillus australimaris strain GS-14 is a promising candidate for industrial PHA production.
• Optimized media parameters can enhance PHA yield.
• Characterization confirmed the biopolymer's properties, suitable for bioplastics.
• This study contributes to developing sustainable bioplastics from microbial sources.