Lipid metabolism in the rumen

https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/86244/1/D_Kishino_Shigenobu.pdf

Production of conjugated fatty acids by lactic acid bacteria.

Publisher Summary
This chapter discusses lipid metabolism in the rumen. Microbial activity in the rumen is responsible for the hydrolysis of esterified plant lipids and for the subsequent hydrogenation of the liberated unsaturated fatty acids. The microorganisms of the rumen are capable of lipid synthesis de novo, using as substrates the short-chain fatty acids produced as end products of microbial carbohydrate and amino-acid metabolism. These activities of hydrolysis, hydrogenation, and synthesis de novo of microbial lipid in the rumen contribute greatly to the characteristic composition of ruminant tissue lipids. Lipids comprise 6%–8% of the dry weight of leaf tissue, and are characterized by their high content of glycolipids and phospholipids. Although the lipid content of forage crops is quite low, the total amount of lipid ingested by the ruminant animal may be considerable because of the large amount of dietary material consumed.

Changing the diet of five lactating cows and one nonlactating cow from high to low roughage induced milk fat depression in the lactating cows and altered the composition of the rumen microflora While the numbers of lactic and propionic acid-producing bacteria increased, the numbers of Butyrivibrio spp decreased The numbers of lipolytic bacteria and the in vitro lipolytic activity of the rumen fluid were also decreased, as was the extent of hydrogenation of linoleic and linolenic acids combined in soybean oil incubated in vitro with rumen fluid It is suggested that among the bacterial population in the rumen the vibrios, which were adversely affected by the low-roughage diets, may contribute significantly to both lipolysis and hydrogenation in the rumen

Effect of low-roughage diets on the microflora and lipid metabolism in the rumen.

Five strictly anaerobic bacteria able to hydrogenate unsaturated fatty acids were isolated from sheep rumen. One was characterized as Ruminococcus albus, two as Eubacterium spp. and two as Fusocillus spp., one of which is named as a new species. The Fusocillus organisms were able to hydrogenate oleic acid and linoleic acid to stearic acid, and linolenic acid to cis-octadec-15-enoic acid. The R. albus and the two Eubacteria did not hydrogenate oleic acid but converted linoleic and linolenic acids to a mixture of octadecenoic acids; trans-octadec-II-enoic acid predominated but several isomeric cis and trans octadecenoic acids were produced together with isomers of non-conjugated octadecadienoic acids. The intermediate and final products of hydrogenation by each organism were compatible with the results from mixed rumen bacteria.

/pdf/the-hydrogenation-of-unsaturated-fatty-acids-by-five-2z54tiw203.pdf

The hydrogenation of unsaturated fatty acids by five bacterial isolates from the sheep rumen, including a new species.

Approximately 70% of the fatty acids present in plant lipids are unsaturated; the major component is cis-9,cis-12,cis-15-octadecatrienoic acid (Garton 1963). After ingestion by ruminants, these acids are readily hydrogenated by microorganisms in the rumen to form a complex mixture of positional and geometrical C18 isomers (Shorland et al. 1957; Ward, Scott, and Dawson 1964; Wilde and Dawson 1966; Kemp and Dawson 1968).

/pdf/hydrogenation-of-c18-unsaturated-fatty-acids-by-pure-4nwwu12vxn.pdf

Hydrogenation of C18 Unsaturated Fatty Acids by Pure Cultures of a Rumen Micrococcus

Difficulty is 'sometimes experienced in distinguishing between O. graminis and sterile fungi which form "Ophiobolus-like" runner hyphae on cereal roots. However, it is possible that nuclear distribution in mycelium may prove a differential character as different distributions have already been reported for O. graminis (Chambers and Flentje 1967) and a cereal root-attacking strain of Rhizoctonia solani (Flentje, Stretton, and Hawn 1963). This paper, therefore, describes comparisons of nuclear distribution in O. graminis and several other cereal root pathogens including a sterile fungus which formed Ophiobolus-like runner hyphae.

/pdf/nuclear-distribution-in-vegetative-cells-of-ophiobolus-3g4ef1qgpy.pdf

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Papers

Hydrogenation of C18 Unsaturated Fatty Acids by Pure Cultures of a Rumen Micrococcus

Nuclear Distribution in Vegetative Cells of Ophiobolus Graminis and other Cereal Root Pathogens