Pseudomonas mediterranea is a bacterium closely related to P. corrugata within the P. fluorescens lineage, producing mcl-PHAs composed of hydroxyalkanoate repeat-unit monomers of six or more carbon atoms on oleic acid, similar to PHAs produced by P. corrugata. The type II PHA genetic system and the repeat-unit composition of the mcl-PHA synthesized by the type strain, P. mediterranea strain CFBP 5447, grown in E* medium with oleic acid as the sole carbon source, have been previously investigated. In the present study we showed P. mediterranea bioconversion of crude and reagent grade glycerol in mcl-PHA, chemically different from that obtained through P. corrugata fermentation. Six P. mediterranea strains were grown in E* medium flask shaken cultures containing reagent grade glycerol or biodiesel - glycerol (at 15, 40 and 80% of glycerol content). Crude and liquid glycerol (15 and 40%) in the substrate gave always an amorphous sticky product, regardless of bacterial strain and glycerol concentration. Best yields were obtained between 48 and 72 hrs, with average of ca. 3.5 g/L CDW and 1.7 g/L crude mcl-PHAs. On the contrary, PHAs obtained after 48 and 72 hrs of fermentation on substrates containing 2% of purified reagent grade (98%) or biodiesel glycerol (80%) were filmable, totally transparent, with a molecular weight of ca. 56 KDa. More than six carbon atoms repeat-unit monomers, with a prevalence of 3-hydroxydecanoate (C10) (60-70%), 3-hydroxyoctanoate (C8), and 3- hydroxy-dodeca-noate (C12 and C12:1) (28-30%) were detected. When liquid glycerol was provided as carbon source a substantial amount of 3-hydroxy-tetradecenoate (C14) (ca. 24%) was also incorporated. Chloroform extrac-tion released a more consistent, rubbery-like, product. In comparative tests, P. corrugata strains A1 and 388 produced only a sticky fragile PHA pellicle and an amorphous and sticky oil, respectively. Molecular mining of whole genome shotgun sequence is in progress.
PRODUCTION OF mcl-PHA BY PSEUDOMONAS MEDITERRANEA CONVERSION OF BIODIESEL-GLYCEROL
PALMERI, ROSA;
2013-01-01
Abstract
Pseudomonas mediterranea is a bacterium closely related to P. corrugata within the P. fluorescens lineage, producing mcl-PHAs composed of hydroxyalkanoate repeat-unit monomers of six or more carbon atoms on oleic acid, similar to PHAs produced by P. corrugata. The type II PHA genetic system and the repeat-unit composition of the mcl-PHA synthesized by the type strain, P. mediterranea strain CFBP 5447, grown in E* medium with oleic acid as the sole carbon source, have been previously investigated. In the present study we showed P. mediterranea bioconversion of crude and reagent grade glycerol in mcl-PHA, chemically different from that obtained through P. corrugata fermentation. Six P. mediterranea strains were grown in E* medium flask shaken cultures containing reagent grade glycerol or biodiesel - glycerol (at 15, 40 and 80% of glycerol content). Crude and liquid glycerol (15 and 40%) in the substrate gave always an amorphous sticky product, regardless of bacterial strain and glycerol concentration. Best yields were obtained between 48 and 72 hrs, with average of ca. 3.5 g/L CDW and 1.7 g/L crude mcl-PHAs. On the contrary, PHAs obtained after 48 and 72 hrs of fermentation on substrates containing 2% of purified reagent grade (98%) or biodiesel glycerol (80%) were filmable, totally transparent, with a molecular weight of ca. 56 KDa. More than six carbon atoms repeat-unit monomers, with a prevalence of 3-hydroxydecanoate (C10) (60-70%), 3-hydroxyoctanoate (C8), and 3- hydroxy-dodeca-noate (C12 and C12:1) (28-30%) were detected. When liquid glycerol was provided as carbon source a substantial amount of 3-hydroxy-tetradecenoate (C14) (ca. 24%) was also incorporated. Chloroform extrac-tion released a more consistent, rubbery-like, product. In comparative tests, P. corrugata strains A1 and 388 produced only a sticky fragile PHA pellicle and an amorphous and sticky oil, respectively. Molecular mining of whole genome shotgun sequence is in progress.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
