In silico prospection of microorganisms to produce polyhydroxyalkanoate from whey: Caulobacter segnis DSM 29236 as a suitable industrial strain

Abstract

Summary Polyhydroxyalkanoates ( PHA s) are polyesters of microbial origin that can be synthesized by prokaryotes from noble sugars or lipids and from complex renewable substrates. They are an attractive alternative to conventional plastics because they are biodegradable and can be produced from renewable resources, such as the surplus of whey from dairy companies. After an in silico screening to search for ß‐galactosidase and PHA polymerase genes, several bacteria were identified as potential PHA producers from whey based on their ability to hydrolyse lactose. Among them, Caulobacter segnis DSM 29236 was selected as a suitable strain to develop a process for whey surplus valorization. This microorganism accumulated 31.5% of cell dry weight ( CDW ) of poly(3‐hydroxybutyrate) ( PHB ) with a titre of 1.5 g l −1 in batch assays. Moreover, the strain accumulated 37% of CDW of PHB and 9.3 g l −1 in fed‐batch mode of operation. This study reveals this species as a PHA producer and experimentally validates the in silico bioprospecting strategy for selecting microorganisms for waste re‐valorization.

Developing Bioprospecting Strategies for Bioplastics Through the Large-Scale Mining of Microbial Genomes

“…The creation of a categorized genomic list of potential PHA producing microbes presents a valuable resource that directs researchers to explicit candidates, as well as access to potential metabolic pathways of interest. A similar bioprospecting strategy was utilized successfully by Bustamante et al (2019) using in silico screening methods to screen for putative PHA and β-galactosidase genes in a select number of microorganisms from literature to find PHA producers that could hydrolyze lactose for utilizing excess whey produced from the dairy industry as a cheap feedstock alternative. In comparison, our study has presented a broader scope by using genomes from large-scale data repositories in the public domain, allowing researchers access to a wider array of candidates which can be sorted by PhaC class, taxonomy and ecological information.…”

From Residues to Added-Value Bacterial Biopolymers as Nanomaterials for Biomedical Applications

“…In order to identify new efficient PHA producers from whey, in silico prospection has proven to constitute a successful strategy. For instance, Caulobacter segnis DSM 29236 accumulates 37% of cell dry weight (CDW) in PHB, producing 9.3 g L −1 in fed-batch cultures [97]. Conversely, the lactose monomers, glucose and galactose, are commonly mineralized by many bacteria; consequently, a hydrolytic pretreatment could broaden the range of bacteria capable of fermenting such a waste stream.…”

What Is New in the Field of Industrial Wastes Conversion into Polyhydroxyalkanoates by Bacteria?

“…Therefore, there is a need to look for microorganisms that accumulate high levels of these biopolyesters using whole cheese whey as a carbon source. Bustamante et al [ 49 ] revealed that Caulobacter segnis DSM 29236 in the fed-batch fermentation reached up to 9.25 g L −1 of P(3HB) by directly hydrolyzing lactose from whey. So far, it is the highest reported P(3HB) concentration in the growth of pure bacterial culture using whole cheese whey without any pre-treatments processes.…”