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Updated: Jan 18, 2026

Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
Effects of nitrogen and phosphorous concentrations on PHA synthesis by PNSB enriched phototrophic mixed microbial
Ramya Ramadoss1,2, Afrah Siddique3, Naim Rashid4
1Mahatma Gandhi Medical Advanced Research Institute (MGMARI), Sri Balaji Vidyapeeth (Deemed to be University), Puducherry, 607403, India.
Abstract:
Global economic burden due to plastic pollution is estimated to be over $3 trillion annually. Bioplastics derived from bacteria-synthesized biopolymers like polyhydroxyalkanoates (PHAs), are a remarkably versatile sustainable alternative. Research on optimal growth-conditions for microbial PHA-synthesis fed-on sustainable substrates, particularly by phototrophic-mixed-cultures (PMC) enriched with purple non-sulphur bacteria (PNSB) is essential. This study intends to understand the effect of nitrogen and phosphorus concentrations on PHA-production by PMC grown using fuel synthesis wastewater (FSW) (organic by-product of Fischer-Tropsch process) as substrate. Stoichiometric quantification and 16 S metagenomic sequencing followed by statistical and bioinformatic analysis were done. High PHA-production (65-82% of biomass) is observed to be induced by Low-Nitrogen conditions enriching Rhodopseudomonas, Paludibacter and Pleomorphomonas and a Low-Phosphorus condition enriching Rhodopseudomonas, Rhodoplanes and Lentimicrobium. Analysis of metabolic-potential revealed 16 enzymes (of 8 different PHA-synthesis-pathways) inherent within the genomes of bacteria enriched by these culture conditions. This study identifies optimal nitrogen and phosphorus concentrations and the corresponding microbial-composition of FSW substrate-grown PMC-system to maximize PHA-production in a laboratory-scale bioprocess.
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