Effects of even and odd number fatty acids cofeeding on PHA production and composition in Pseudomonas putida Bet001 isolated from palm oil mill effluent

Abstract

The biosynthesis of medium-chain-length poly-3-hydroxyalkanoates by Pseudomonas putida Bet001 cultivated on mixed carbon sources was investigated. The mixed carbon sources consisted of heptanoic acid (HA) and oleic acid (OA). A relatively low PHA content at 1.2% (w/w) and 11.4% (w/w) was obtained when HA or OA was used as the sole carbon source. When these fatty acids were supplied as a mixture, PHA content increased threefold. Interestingly, the mixture-derived PHA composed of both odd and even monomer units, namely. 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate and no unsaturated monomer was detected. It is hypothesized that the even-numbered monomers were derived primarily from OA, whereas the odd-numbered monomer was derived from HA. This also points out to an efficient and yet distinct fatty acids metabolism that fed the PHA biosynthesis machinery of this particular microorganism. PHA obtained was elastomeric because melting temperature (Tm ) and crystallinity were absent. It showed good thermal stability with degradation temperature (Td ) ranging from 275.96 to 283.05 °C.

A porous medium‐chain‐length poly(3‐hydroxyalkanoates)/hydroxyapatite composite as scaffold for bone tissue engineering

“…Culture condition is one of the main factors that affects the production of PHA. Various types of mcl‐PHA monomeric composition can be synthesized by providing different carbon sources in the cultivation medium . In this study, mcl‐PHA was produced through fed‐batch fermentation process by P. putida BET 001.…”

“…Purification steps were repeated three times by dissolving the PHA in acetone followed by re‐precipitation in cold methanol. The PHA composition and its cellular content were analyzed using gas chromatography (GC) . The extracted mcl‐PHA composed of three different monomers viz .…”

Current trends in medium‐chain‐length polyhydroxyalkanoates: Microbial production, purification, and characterization

“…Most mcl-PHAs with saturated monomers exhibit single-step degradation in the temperature range 255−350 • C. Incorporating monomers with a longer alkyl chain has increased T d [45,53]. Razaif-Mazinah et al [40] stated that a unique monomer distribution and shorter monomeric chain lengths resulted in a lower T d . Still, the variation is only in a narrow range (275−283 • C).…”

“…After isolating the biomass from the culture broth by centrifugation or filtration, the harvested cells are either freeze‐dried [ 61 , 62 ] or oven‐dried [ 40 ]. Several studies have shown that biomass should be pre‐treated to weaken the cell membrane and promote cell lysis.…”

“…To achieve this, dried biomass is degreased overnight using ethanol [ 34 ] or methanol [ 63 ] at room temperature or ethanol by reflux [ 64 ]. Then, the biomass is washed with saline solution and n‐hexane to remove loosely bound non‐PHA material [ 40 ] and excess fatty acids, respectively [ 32 ]. Moreover, heat pre‐treatment by autoclaving the fermentation medium supported cell lysis and nucleic acid solubilization in enzymatic DSP processes [ 65 ].…”