Thauera aminoaromatica MZ1T Identified as a Polyhydroxyalkanoate-Producing Bacterium within a Mixed Microbial Consortium.

Wen Zhou,Jan Pier Wempe,Gert-Jan W Euverink,Dana I Colpa,Marc C A Stuart,Janneke Krooneman,Jelmer Tamis

doi:10.3390/bioengineering7010019

Wen Zhou, Jan Pier Wempe + Show 5 more

Open Access

https://doi.org/10.3390/bioengineering7010019

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Abstract

Polyhydroxyalkanoates (PHAs) form a highly promising class of bioplastics for the transition from fossil fuel-based plastics to bio-renewable and biodegradable plastics. Mixed microbial consortia (MMC) are known to be able to produce PHAs from organic waste streams. Knowledge of key-microbes and their characteristics in PHA-producing consortia is necessary for further process optimization and direction towards synthesis of specific types of PHAs. In this study, a PHA-producing mixed microbial consortium (MMC) from an industrial pilot plant was characterized and further enriched on acetate in a laboratory-scale selector with a working volume of 5 L. 16S-rDNA microbiological population analysis of both the industrial pilot plant and the 5 L selector revealed that the most dominant species within the population is Thauera aminoaromatica MZ1T, a Gram-negative beta-proteobacterium belonging to the order of the Rhodocyclales. The relative abundance of this Thauera species increased from 24 to 40% after two months of enrichment in the selector-system, indicating a competitive advantage, possibly due to the storage of a reserve material such as PHA. First experiments with T. aminoaromatica MZ1T showed multiple intracellular granules when grown in pure culture on a growth medium with a C:N ratio of 10:1 and acetate as a carbon source. Nuclear magnetic resonance (NMR) analyses upon extraction of PHA from the pure culture confirmed polyhydroxybutyrate production by T. aminoaromatica MZ1T.

Highlights

The production and use of fossil-based plastic materials became ubiquitous, especially after the second world war
The tide must be turned from an ecological point of view by (1) reducing the use of plastics, (2) recycling of existing plastics, (3) production of plastics that are not petrochemically derived and that are biodegradable once they end up in the environment
To enhance the selection of the PHA-producing bacteria from the pilot reactor in our 5 L bioreactor, a feast–famine regime was combined with gravitational settling

Summary

Introduction

The production and use of fossil-based plastic materials became ubiquitous, especially after the second world war. Plastics play an indispensable role in our daily life. In the past decades, it has become evident that these plastics persist in nature and have accumulated to incredibly high volumes and become severe ecological threats. The immense volume of the plastic soup in our oceanic ecosystems is one of the most eye-catching examples [1]. The global plastics production reached approximately 360 million tons and shows an increasing trend [1]. The tide must be turned from an ecological point of view by (1) reducing the use of plastics, (2) recycling of existing plastics, (3) production of plastics that are not petrochemically derived and that are biodegradable once they end up in the environment

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