A new research study has identified Bacillus australimaris, isolated from soils around Manipal, India, as a potent producer of polyhydroxyalkanoates (PHAs), which serve as environmentally friendly alternatives to conventional plastics. The biosynthesis and properties of these microbial polyesters highlight their potential role in addressing the pressing plastic pollution crisis.
The surge of plastic production since the 1970s has created significant environmental challenges, with projections indicating the global output could reach 1,100 million tons by 2050 if current trends continue. About 36% of all plastics produced are used for packaging, much of which ends up as unregulated waste, adversely impacting ecosystems worldwide.
Recognizing the need for sustainable materials, researchers have turned to microbial biopolymers like PHAS for their biodegradability and potential to replace harmful plastics. This study, published on March 11, 2025, focused on screening soil bacterial isolates for their capacity to produce PHAS, with the aim of optimizing production methods to make bioplastics more accessible.
A total of 17 isolates were successfully screened using Sudan black staining, which indicated the presence of intracellular PHAS. Among these, isolate GS-14 stood out with the highest production levels, verified through quantitative analysis using crotonic acid as the standard.
The researchers determined the chemical characteristics of the extracted PHA using Fourier Transform Infrared Spectroscopy (FTIR) and Liquid Chromatography-Mass Spectrometry (LC-MS). FTIR analysis confirmed typical absorption bands attributed to PHAS, with the identification of key structural features, including a carbonyl peak at 1732 cm⁻¹. The molecular mass of the produced polymer, estimated between 5,000 and 20,000 Da, was substantiated by mass spectrometry. Differential Scanning Calorimetry (DSC) showcased thermal properties relevant for assessing the material’s practical applications, presenting for the first time the exothermic peak at 174 °C, which is significant for calculating the degree of crystallinity, directly influencing mechanical strength.
The authors of the article stated, “Isolate GS-14 presented the highest yield, which was determined by extrapol… the standard curve.” This high yield positions GS-14 as not just another microbial isolate but potentially as a feasible candidate for developing cost-effective and sustainable bioplastics.
Identification of the isolate as Bacillus australimaris was confirmed through advanced genetic sequencing techniques, particularly 16 S ribosomal RNA analysis. The sequence was deposited with the National Center for Biotechnology Information (NCBI), enabling future researchers to track and utilize this discovery.
To achieve optimal production of PHA, the research team employed statistical analysis using Minitab software to examine various media components and their effects on yield. Their findings revealed the significant impact of nutrient concentrations on biomass and PHA production, highlighting ammonia sulfate as particularly influential—a notable insight since previous studies had not classified it as critically beneficial for PHA accumulation.
The statistical analysis illustrated significant variations, indicating the optimal conditions for PHA production, thereby providing concrete data to facilitate broader applications. The researchers also used contour plots to visualize interactions among various factors like nutrient concentrations, derived from the Plackett–Burman experimental design.
This comprehensive approach not only establishes Bacillus australimaris as promising for bioplastic applications but positions it against the backdrop of urgent environmental needs and sustainability objectives.
Going forward, researchers aim to scale up production techniques, leveraging agricultural waste as feedstock for Bacillus australimaris GS-14, promoting not just reduced reliance on petroleum-based plastics but also contributing to reducing ecological footprints.
The recognition of PHAS, particularly through this research, is significant as it paves the way toward utilizing microbial biodiversity as sustainable solutions to plastic pollution. Promising future avenues include investigating PHA properties for various applications, including medical uses, where their biocompatibility offers additional advantages.
This study reinforces the importance of exploring natural biological resources as we confront the plastic crisis and move toward adopting environmentally friendly practices.