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Abstract Petroleum‐based plastics levy significant environmental and economic costs that can be alleviated with sustainably sourced, biodegradable, and bio‐based polymers such as polyhydroxyalkanoates (PHAs). However, industrial‐scale production of PHAs faces barriers stemming from insufficient product yields and high costs. To address these challenges, we must look beyond the current suite of microbes for PHA production and investigate non‐model organisms with versatile metabolisms. In that vein, we assessed PHA production by the photosynthetic purple non‐sulfur bacteria (PNSB)Rhodomicrobium vannieliiandRhodomicrobium udaipurense.We show that both species accumulate PHA across photo‐heterotrophic, photo‐hydrogenotrophic, photo‐ferrotrophic, and photo‐electrotrophic growth conditions, with either ammonium chloride (NH4Cl) or dinitrogen gas (N2) as nitrogen sources. Our data indicate that nitrogen source plays a significant role in dictating PHA synthesis, with N2fixation promoting PHA production during photoheterotrophy and photoelectrotrophy but inhibiting production during photohydrogenotrophy and photoferrotrophy. We observed the highest PHA titres (up to 44.08 mg/L, or 43.61% cell dry weight) when cells were grown photoheterotrophically on sodium butyrate with N2, while production was at its lowest during photoelectrotrophy (as low as 0.04 mg/L, or 0.16% cell dry weight). We also find that photohydrogenotrophically grown cells supplemented with NH4Cl exhibit the highest electron yields – up to 58.89% – while photoheterotrophy demonstrated the lowest (0.27%–1.39%). Finally, we highlight superior electron conversion and PHA production compared to a related PNSB,Rhodopseudomonas palustrisTIE‐1. This study illustrates the value of studying non‐model organisms likeRhodomicrobiumfor sustainable PHA production and indicates future directions for exploring PNSB metabolisms.
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This content will become publicly available on September 17, 2026
State-of-the-art methods for quantifying microbial polyhydroxyalkanoates
ABSTRACT Polyhydroxyalkanoates are a diverse class of microbially synthesized polymers that are used to make bioplastics with a wide range of applications. As interest in polyhydroxyalkanoates (PHAs) grows, researchers are faced with a challenge: how best to use the resources at their disposal to reliably quantify PHA produced by their microbe(s) of choice. Investigators must weigh the pros and cons of each method against logistical constraints (e.g., time, money, and equipment) and technical concerns (e.g., accuracy and sensitivity). At the same time, the broader community of scientists researching PHAs should aspire to land on a set of best practices. To this end, we must continually audit our methods. Here, we offer readers a snapshot of popular and emerging approaches for quantifying PHA in the lab. For each method, we provide an overview,list the primary equipment, briefly describe the methods, including improvements or iterations, and discuss the pros and cons of the approach. Along the way, we highlight gaps in research and make recommendations about best practices and future directions.
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- PAR ID:
- 10641445
- Editor(s):
- Nikel, Pablo Ivan
- Publisher / Repository:
- American Society for Microbiology
- Date Published:
- Journal Name:
- Applied and Environmental Microbiology
- Volume:
- 91
- Issue:
- 9
- ISSN:
- 0099-2240
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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