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Polyhydroxyalkanoate (PHA) production by a mixed microbial culture using sugar molasses: effect of the influent

M G E Albuquerque1, C A V Torres, M A M Reis

  • 1REQUIMTE/CQFB, Department of Chemistry, FCT, Universidade Nova de Lisboa, P-2829-516 Caparica, Portugal.

Water Research
|April 30, 2010
PubMed

Insights

Optimizing influent substrate concentration is key for selecting Polyhydroxyalkanoate (PHA) storing microbial cultures. A concentration of 45Cmmol VFA/L yielded the best PHA accumulation, reaching 74.6% PHA content.

Area of Science:

  • Biotechnology
  • Microbial Ecology
  • Biopolymer Production

Background:

  • Polyhydroxyalkanoate (PHA) production relies heavily on effective microbial culture selection.
  • Mixed Microbial Cultures (MMC) offer a cost-effective route to PHA synthesis.
  • Optimizing selection conditions is crucial for maximizing PHA accumulation.

Purpose of the Study:

  • To investigate the impact of influent substrate concentration on PHA-storing culture selection.
  • To identify optimal carbon substrate levels for PHA accumulation using fermented sugar molasses.
  • To understand the kinetic and physiological effects of varying substrate concentrations and feast-to-famine ratios.

Main Methods:

  • Assessing PHA accumulation in MMC under different influent volatile fatty acid (VFA) concentrations (30-60Cmmol VFA/L).
  • Utilizing fermented sugar molasses as a complex feedstock.
  • Analyzing microbial population dynamics and PHA storage capacity through batch studies.

Main Results:

  • Substrate concentrations of 30 and 45Cmmol VFA/L induced substrate-dependent kinetic limitations.
  • A concentration of 60Cmmol VFA/L led to growth limitation due to magnesium deficiency and high pH.
  • The culture selected at 45Cmmol VFA/L exhibited the highest PHA-storing capacity (88% PHA-storing organisms, 74.6% PHA content).

Conclusions:

  • Influent substrate concentration significantly influences PHA-storing culture selection and performance.
  • Optimal selection at 45Cmmol VFA/L balances substrate availability and avoids nutrient limitations.
  • This study demonstrates a method for enhancing PHA production efficiency through optimized MMC selection.

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