Medium chain length polyhydroxyalkanoates consisting primarily of unsaturated 3-hydroxy-5-cis-dodecanoate synthesized by newly isolated bacteria using crude glycerol

Abstract

BackgroundOur study aimed to search for novel bacteria capable of producing polyhydroxyalkanoates (PHAs) using crude glycerol residue obtained from biodiesel production in which used cooking oils were the substrates.ResultsNewly isolated bacteria from soils in Thailand were screened for the efficient production of PHAs from crude glycerol. The bacterial strains were cultivated on glucose, refined glycerol, crude glycerol, or various cooking oils (canola oil, palm oil, soybean oil, sunflower oil, corn oil, grape seed oil, olive oil, rice bran oil, camellia seed oil) for growth and PHA production. The effects of the total organic carbon (TOC) concentration and the mole ratio of carbon to nitrogen were investigated in batch cultivation. 1H NMR, two dimensional-1H-correlation spectroscopy (2D-1H-COSY) and 13C NMR analyses confirmed four bacterial strains were capable of producing medium-chain-length PHAs (mcl-PHAs), consisting of 3-hydroxyoctanoate (3HO) and 3-hydroxy-5-cis-dodecanoate (3H5DD), from crude glycerol. On the basis of phenotypic features and genotypic investigations, the bacterial strains were assigned as: ASC1, Acinetobacter genus (94.9 % similarity); ASC2, Pseudomonas genus (99.2 % similarity); ASC3, Enterobacter genus (99.2 % similarity); ASC4, Bacillus genus (98.4 % similarity). The highest amount of mcl-PHAs, 17.5 ± 0.8 g/L (content 61.8 ± 3.3 % wt), with 3HO (14.7 ± 2.2 mol %), 3H5DD (85.3 ± 2.2 mol %), and a total biomass of 32.3 ± 0.3 g/L, was obtained from Pseudomonas sp. ASC2 in batch cultivation after 36 h. The mcl-PHAs recovered had a number-average molecular weight (MN) of 3.6 × 104 Da. Homopolymeric 3H5DD was obtained when the cultivation time was prolonged to 96 h.ConclusionsNovel PHA-producing strains were isolated and identified. These bacterial strains are able to produce mcl-PHAs from crude glycerol. The mcl-PHAs produced contained a high percentage of 3H5DD, which suggests their future application as softeners mixed with other biomaterials. The unsaturated side chain of 3H5DD monomers containing double bounds offers additional potential for improving the properties of the mcl-PHAs or extending their applications to the food industry.

Application of cider by-products for medium chain length polyhydroxyalkanoate production by Pseudomonas putida KT2440

“…Medium-chain-length PHAs (mcl-PHAs) that contain 6-14 carbon atoms in their monomeric units, are produced by Pseudomonas strains. It has been previously reported that these bacteria can biosynthesize saturated and unsaturated monomers, which in combination with long chains, leads to highly amorphous polymers [2][3][4] . Moreover, there are several studies that demonstrate the biocompatibility of these polymers [5,6] .…”

Polyhydroxyalkanoate production using two‐stage continuous stirred tank activated sludge systems with glycerol as a carbon source

“…and bacteria in the families Rhodocyclaceae, Comamonadaceae, Xanthobacteraceae, Enterobacteriaceae, and Bradyrhizobiaceae have been reported to accumulate PHA. [30][31][32][33][34] All of these groups of microorganisms belong to proteobacteria in the class alphaproteobacteria, betaproteobacteria, or gammaproteobacteria.…”

Enhancement of Polyhydroxyalkanoate Production by Co-feeding Lignin Derivatives With Glycerol in Pseudomonas Putida KT2440

“…For the cell samples, the NMR sample solutions were sonicated for 4 h. The COSY, HSQC and HMBC experiments were carried out with standard Bruker sequences "cosyetgp", "hsqcetgpsisp2.2" and "hmbccgpndqf" respectively, with a scan number of 16 for COSY and of 96 for HSQC and HMBC. All the NMR spectra were analysed with the software Mestrenova (version of 12.0.2) [83].…”