An updated overview on the regulatory circuits of polyhydroxyalkanoates synthesis

Abstract

Polyhydroxyalkanoates (PHA) are a promising and sustainable alternative to the petroleum-based synthetic plastics. Regulation of PHA synthesis is receiving considerable importance as engineering the regulatory factors might help developing strains with improved PHA-producing abilities. PHA synthesis is dedicatedly regulated by a number of regulatory networks. They tightly control the PHA content, granule size and their distribution in cells. Most PHAaccumulating microorganisms have multiple regulatory networks that impart a combined effect on PHA metabolism. Among them, several factors ranging from global to specific regulators, have been identified and characterized till now. This review is an attempt to categorically summarize the diverse regulatory circuits that operate in some important PHA-producing microorganisms. However, in several organisms, the detailed mechanisms involved in the regulation of PHA synthesis is not well-explored and hence further research is needed. The information presented in this review might help researcher to identify the prevailing research gaps in PHA regulation.

Biosynthesis and Properties of a P(3HB-co-3HV-co-4HV) Produced by Cupriavidus necator B-10646

“…As is known, homopolymer P(3HB) is characterized by: softening temperature-about 110 °C, crystallization range (T cryst )-85–110 °C; melting point (T melt )and thermal degradation temperature (T degr ) have a gap of at least 100 °C and are in the range of 160–180 and 270–280 °C respectively. As a rule, PHA copolymer samples have lower T melt and T degr [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ].…”

“…Polyhydroxyalkanoates (PHA) are actively studied degradable biopolymers intended to solve the problems associated with the global accumulation of plastic waste in the biosphere and with the elimination of deficit in functional materials for special purposes [ 1 , 2 , 3 , 4 ]. PHA is a family of polymers of various compositions whose physicochemical properties (molecular weight, crystallinity, degradation rates in biological media) vary significantly depending on the chemical structure [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Identification of microorganisms and conditions that make it possible to obtain polymers of various chemical compositions is a necessary condition for the development of methods for the synthesis of new polymers with desired properties.…”

Polyhydroxyalkanoate production from animal by‐products: Development of a pneumatic feeding system for solid fat/protein‐emulsions

“…Nevertheless, an increasing CDW and PHA concentration was observed with a maximum of 7.8 g L −1 and 6.1 g L −1 respectively. These findings suggest that the C/N ratio is sufficiently high to induce nitrogen‐depleted conditions while carbon is in excess; otherwise, such a high intracellular PHA content would not be observable (Mitra et al, 2021 ). When the same feedstock was used at a concentration of 10 g L −1 in a previous study with urea as an additional nitrogen source, a higher CDW was obtained but the PHA content in the cells was lower (Saad et al, 2021 ).…”

When microbial biotechnology meets material engineering

“…Differences between PHA structures are mainly due to the enzymatic specificity of the PHA synthase, the key enzyme involved in PHA biosynthesis, which can accept precursors of a certain carbon‐length, as well as the substrate employed, along with the metabolic and regulatory networks in each species. The specific aspects of the metabolic and regulatory pathways involved in the PHA biosynthesis/depolymerization cycle have been described and reviewed (Mezzina et al ., 2021; Mitra et al ., 2021).…”