Dynamics of Microbial Communities in Phototrophic Polyhydroxyalkanoate Accumulating Cultures.

Juliana R Almeida,Maria A M Reis,Gilda Carvalho,Adrian Oehmen,Joana C Fradinho

doi:10.3390/microorganisms10020351

Juliana R Almeida, Maria A M Reis + Show 3 more

Open Access

https://doi.org/10.3390/microorganisms10020351

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Journal: Microorganisms	Publication Date: Feb 3, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: Universidade Nova de Lisboa

Abstract

Phototrophic mixed cultures (PMC) are versatile systems which can be applied for waste streams, valorisation and production of added-value compounds, such as polyhydroxyalkanoates (PHA). This work evaluates the influence of different operational conditions on the bacterial communities reported in PMC systems with PHA production capabilities. Eleven PMCs, fed either with acetate or fermented wastewater, and selected under either feast and famine (FF) or permanent feast (PF) regimes, were evaluated. Overall, results identified Chromatiaceae members as the main phototrophic PHA producers, along with Rhodopseudomonas, Rhodobacter and Rhizobium. The findings show that Chromatiaceae were favoured under operating conditions with high carbon concentrations, and particularly under the PF regime. In FF systems fed with fermented wastewater, the results indicate that increasing the organic loading rate enriches for Rhodopseudomonas, Rhizobium and Hyphomicrobiaceae, which together with Rhodobacter and Chromatiaceae, were likely responsible for PHA storage. In addition, high-sugar feedstock impairs PHA production under PF conditions (fermentative bacteria dominance), which does not occur under FF. This characterization of the communities responsible for PHA accumulation helps to define improved operational strategies for PHA production with PMC.

Highlights

The current over-exploitation of natural resources, along with the release of polluting waste streams, are causing an unprecedented impact on the climate and ecosystems [1].Coupling environmental protection with economic growth requires the implementation of sustainable practices, which include the valorisation of wastes and their reintegration into the process chain, under the so-called circular economy
The analysis of the gene amplicon sequences targeting the bacterial 16S rRNA gene variable region 1–3, combined with taxonomic classification, allowed us to estimate the abundance of different microbial groups for each Phototrophic mixed cultures (PMC) community
This work provided an overview of the bacterial communities that can be enriched in PMC systems designed for PHA production and operated either with synthetic acetate feed or real fermented feedstock, under different operating conditions

Summary

Introduction

The current over-exploitation of natural resources, along with the release of polluting waste streams, are causing an unprecedented impact on the climate and ecosystems [1]. Coupling environmental protection with economic growth requires the implementation of sustainable practices, which include the valorisation of wastes and their reintegration into the process chain, under the so-called circular economy. Bioprocesses can contribute to this valorisation, and agricultural wastes, flue gases, domestic and industrial wastewaters are examples of waste streams that have been targeted for valorisation through e.g., resource recovery, bioconversion to new value-added compounds and energy production [2,3]. By exploring the aptitudes of different microorganisms, a variety of biological systems can be applied to each waste stream scenario.

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