Quantitative ‘Omics Analyses of Medium Chain Length Polyhydroxyalkanaote Metabolism in Pseudomonas putida LS46 Cultured with Waste Glycerol and Waste Fatty Acids

Medium chain-length polyhydroxyalkanoates (mcl-PHA) were produced by Pseudomonas putida LS46 cultured with a variety of carbohydrate and fatty acid substrates. The monomer compositions and molecular weights of the polymers varied greatly and was dependent on whether the substrate was metabolized via the fatty acid degradation or the de novo fatty acid synthesis pathways. The highest molecular weights were obtained from medium chain-length fatty acids, whereas low molecular weights were obtained from longer chain-length and more unsaturated fatty acids or carbohydrates. The differences in monomer compositions and molecular weights due to the choice of substrate did not affect the polymer thermal degradation point. The glass transition temperatures varied from −39.4°C to −52.7°C. The melting points, when observed, ranged from 43.2°C to 51.2°C. However, a profound substrate effect was observed on the crystallinity of these polymers. Reduced crystallinity was observed when the monomer compositions deviated away from C8–C10 monomer lengths. The highest crystallinity was observed from medium chain-length fatty acids, which resulted in polymers with the highest tensile strength. The polymer produced from octanoic acid exhibited the highest tensile strength of 4.3 MPa with an elongation-at-break of 162%, whereas the polymers produced from unsaturated, long-chain fatty acids remained amorphous. A comparative analysis of the substrate effect on the physical-mechanical and thermal properties of mcl-PHAs better clarifies the relationship between the monomer composition and their potential applications, and also aids to direct future PHA synthesis research toward properties of interest.

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Production of Medium-Chain-Length Poly(3-hydroxyalkanoates) from Crude Fatty Acids Mixture by Pseudomonas putida

Food and Bioproducts Processing ◽

10.1205/fbp06017 ◽

2007 ◽

Vol 85 (2) ◽

pp. 104-119 ◽

Cited By ~ 22

Author(s):

M.S.M. Annuar ◽

I.K.P. Tan ◽

S. Ibrahim ◽

K.B. Ramachandran

Keyword(s):

Fatty Acids ◽

Pseudomonas Putida ◽

Chain Length ◽

Medium Chain ◽

Medium Chain Length

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Kinetics of medium-chain-length polyhydroxyalkanoate production by a novel isolate of Pseudomonas putida LS46

Canadian Journal of Microbiology ◽

10.1139/w2012-074 ◽

2012 ◽

Vol 58 (8) ◽

pp. 982-989 ◽

Cited By ~ 24

Author(s):

Parveen K. Sharma ◽

Jilagamazhi Fu ◽

Nazim Cicek ◽

Richard Sparling ◽

David B. Levin

Keyword(s):

Pseudomonas Putida ◽

Chain Length ◽

Saturated Fatty Acids ◽

Dry Mass ◽

Nucleotide Sequence Analysis ◽

Glucose Medium ◽

Medium Chain ◽

Medium Chain Length ◽

Pha Production ◽

Nitrogen Excess

Six bacteria that synthesize medium-chain-length polyhydroxyalkanoates (mcl-PHAs) were isolated from sewage sludge and hog barn wash and identified as strains of Pseudomonas and Comamonas by 16S rDNA gene sequencing. One isolate, Pseudomonas putida LS46, showed good PHA production (22% of cell dry mass) in glucose medium, and it was selected for further studies. While it is closely related to other P. putida strains (F1, KT2440, BIRD-1, GB-1, S16, and W619), P. putida LS46 was genetically distinct from these other strains on the basis of nucleotide sequence analysis of the cpn60 gene hypervariable region. PHA production was detected as early as 12 h in both nitrogen-limited and nitrogen-excess conditions. The increase in PHA production after 48 h was higher in nitrogen-limited cultures than in nitrogen-excess cultures. Pseudomonas putida LS46 produced mcl-PHAs when cultured with glucose, glycerol, or C6–C14 saturated fatty acids as carbon sources, and mcl-PHAs accounted for 56% of the cell dry mass when cells were batch cultured in medium containing 20 mmol/L octanoate. Although 3-hydroxydecanoate was the major mcl-PHA monomer (58.1–68.8 mol%) in P. putida LS46 cultured in glucose medium, 3-hydroxyoctanoate was the major monomer produced in octanoate medium (88 mol%).

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Effects of propionate and carnitine on the hepatic oxidation of short- and medium-chain-length fatty acids

Biochemical Journal ◽

10.1042/bj2500819 ◽

1988 ◽

Vol 250 (3) ◽

pp. 819-825 ◽

Cited By ~ 52

Author(s):

E P Brass ◽

R A Beyerinck

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Organic Acid ◽

Chain Length ◽

Ketone Body ◽

Acetyl Coa ◽

Body Formation ◽

Medium Chain ◽

Medium Chain Length ◽

Hepatic Oxidation

Accumulation of propionate, or its metabolic product propionyl-CoA, can disrupt normal cellular metabolism. The present study examined the effects of propionate, or propionyl-CoA generated during the oxidation of odd-chain-length fatty acids, on hepatic oxidation of short- and medium-chain-length fatty acids. In isolated hepatocytes, ketone-body formation from odd-chain-length fatty acids was slow as compared with even-chain-length fatty acid substrates, and increased as the carbon chain length was increased from five to seven to nine. In contrast, rates of ketogenesis from butyrate, hexonoate and octanoate were all approximately equal. Propionate (10 mM) inhibited ketogenesis from butyrate, hexanoate and octanoate by 81%, 53% and 18% respectively. Addition of carnitine had no effect on ketogenesis from the even-chain-length fatty acids, but increased the rate of ketone-body formation from pentanoate (by 53%), heptanoate (by 28%) and from butyrate or hexanoate in the presence of propionate. The inhibitory effect of propionate could not be explained by shunting acetyl-CoA into the tricarboxylic acid cycle, as CO2 formation from butyrate was also decreased by propionate. Examination of the hepatocyte CoA pool during oxidation of butyrate demonstrated that addition of propionate decreased acetyl-CoA and CoA as propionyl-CoA accumulated. Addition of carnitine decreased propionyl-CoA by 50% (associated with production of propionylcarnitine) and increased acetyl-CoA and CoA. Similar changes in the CoA pool were seen during the oxidation of pentanoate. These results demonstrate that accumulation of propionyl-CoA results in inhibition of short-chain fatty acid oxidation. Carnitine can partially reverse this inhibition. Changes in the hepatocyte CoA pool are consistent with carnitine acting by generating propionylcarnitine, thereby decreasing propionyl-CoA and increasing availability of free CoA. The data provide further evidence of the potential cellular toxicity from organic acid accretion, and supports the concept that carnitine's interaction with the cellular CoA pool can have a beneficial effect on cellular metabolism and function under conditions of unusual organic acid accumulation.

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