Effect of short- and medium-chain fatty acid mixture on polyhydroxyalkanoate production by Pseudomonas strains grown under different culture conditions

Abstract

Short- and medium-chain fatty acids (SMCFAs) derived from the acidogenic anaerobic mixed culture fermentation of acid whey obtained from a crude cheese production line and their synthetic mixture that simulates a real SMCFA-rich stream were evaluated for polyhydroxyalkanoate (PHA) production. Three individual Pseudomonas sp. strains showed different capabilities of growing and producing PHAs in the presence of a synthetic mixture of SMCFAs. Pseudomonas sp. GL06 exhibited the highest SMCFA tolerance and produced PHAs with the highest productivity (2.7 mg/L h). Based on these observations, this strain was selected for further investigations on PHA production in a fed-batch bioreactor with a SMCFA-rich stream extracted from the effluent. The results showed that PHA productivity reached up to 4.5 mg/L h at 24 h of fermentation together with the ammonium exhaustion in the growth medium. Moreover, the PHA monomeric composition varied with the bacterial strain and the type of the growth medium used. Furthermore, a differential scanning calorimetric and thermogravimetric analysis showed that a short- and medium-chain-length PHA copolymer made of 3-hydroxybutyric, -hexanoic, -octanoic, -decanoic, and -dodecanoic has promising properties. The ability of Pseudomonas sp. to produce tailored PHA copolymers together with the range of possible applications opens new perspectives in the development of PHA bioproduction as a part of an integrated valorization process of SMCFAs derived from waste streams.

Genetic characterization of a novel Salinicola salarius isolate applied for the bioconversion of agro-industrial wastes into polyhydroxybutyrate

“…Numerous studies have documented PHB production from whey by indigenous microorganisms. Elmashi et al and Szacherska et al reported PHB production from whey using Bacillus cereus and Pseudomonas sp ., respectively [ 57 , 58 ]. Whey also necessitates a costly treatment prior to disposal, making it an attractive raw material for PHB manufacturing.…”

Advances in the Food Packaging Production from Agri-Food Waste and By-Products: Market Trends for a Sustainable Development

“…Among the PHAs, the production of medium-chain-length PHA (mcl-PHA) has attracted much attention because of its favorable properties, as its extraction, purification, and recycling are easier and cost-effective due to its higher solubility, which is related to its low crystallinity [86]. Awasthi et al and Pereira et al [87,88] reported the production of mcl-PHA using watermelon and apple PHAs are considered an alternative material for conventional plastics due to their similarity to petrochemically derived plastics, better hydrophobicity, relatively high melting point, and optical purity [83]. Current research demonstrates the existence of approximately 150 different PHAs [84], which gained worldwide interest because of their biodegradable, biocompatible, non-toxic, and thermoplastic nature; the polymer characteristics are influenced by the number of carbon atoms present in each HA monomer unit [83].…”

“…Awasthi et al and Pereira et al [87,88] reported the production of mcl-PHA using watermelon and apple PHAs are considered an alternative material for conventional plastics due to their similarity to petrochemically derived plastics, better hydrophobicity, relatively high melting point, and optical purity [83]. Current research demonstrates the existence of approximately 150 different PHAs [84], which gained worldwide interest because of their biodegradable, biocompatible, non-toxic, and thermoplastic nature; the polymer characteristics are influenced by the number of carbon atoms present in each HA monomer unit [83].…”

Copolymers and Blends Based on 3-Hydroxybutyrate and 3-Hydroxyvalerate Units

“…Based on the length of their carbon side chains, PHAs are systematically classified into short chain lengths (4 to 5 carbons) and medium chain lengths (6 to 12 carbons), as illustrated in Figure 3. Some studies have observed the presence of long-chain PHAs containing more than 14 carbon units; however, research on these PHAs is still limited [18,19]. In addition to simple PHAs, copolymers consisting of two different monomers are also identified.…”