Screening And Identification Of Lactobacillus Produced CLA In Silage And Studies On Its Effect On The Production Of CLA In Fermented Silage

Linoleic acid is an 18-carbon unsaturated fatty acid,are thought to be active as potential antioxidant,anticarcinogenic,immune-modulating agents,and antiobesity,and so on.The natural CLA are generated from microorganism.The CLA of food come from milk and meat of ruminant mainly.So the chemical synthetic CLA were added to the feed directly by exogenousing to get mare CLA,but the method by fermenting to increasing the content of CLA in feed has not been reported.The experiment detected the content of CLA in maize silage,identified after the secretor screened,and then regulated the condition of the strain in silage,to definite the optimal inoculum size and the proportion of lipid.This experimentation used the Ultraviolet Spectrophotometer measuration to measurate the content of conjugated linoleic acid in maize silage.The result showed us that the content was mainly between 2～4μg/g,and it indicated that there are some existent microbe which can turns linoleic acid into conjugated linoleic acid in silage,which lactobacillus may be the mostly one.A strain named ANCLA01 was selected from the strains screened from maize silage for bioconversion of linoleic acid into conjugated linoleic acid(CLA),and its CLA production in the fermentation broth was 33.442μg/ml;The germ was a Gram-positive rod, and showing as dull circle,short but straight,and which did not produce spore.Lactic Acid was produced after being fermented,and it is a kind of Bacillus acidi lactici belonged to type B of homofermentation as well which had special requirements of substrate in medium,moreover,whose base sequence of 16S ribosomal RNA gene showed 99.93% sequence similarity with Lactobacillus plantarum strain L5,the accessions of GenBank is EF185922.All results include the identification by traditional methods to make clear that the strain was Lactobacillus plantarum.Thus a conclusion drawns that there are some bacteria which having the ability in bioconversion of linoleic acid into CLA in Silage.The process conditions of transformation linoleic acid into conjugated linoleic acid via Lactobacillus plantarum strain ANCLA01 were optimized.The optimum conditions were linoleic acid ratio 0.075(v/v),reaction temperature 35℃,incubation time 28 h,and pH 7.0.Under optimum conditions,the yield of conjugated linoleic acid was 290μg/ml, and microaerobic conditions were in favor of increasing the amounts of CLA.The production of CLA in root tuber of sweet potato silage,potato silage,carrot silage and radish silage added L.plantarum ANCLA01 and sunflower oil were analyzed.The result indicated that the produed CLA was influenced less than 0.001 by above two factors, and the CLA content in four silages showed the reduced tendency after first increases either increased L.plantarum ANCLA01 or sunflower oil.In sum,the highest CLA were produced when added 6×10~5cfu/g L.plantarum ANCLA01 besides 0.009～0.012g/g sunflower oil in four silage,meanwhile,the potato silage was more suitable than others to produce CLA,and the highest production achieved 9.246μg/g.Thus a conclusion may be drawn that selected L.plantarum ANCLA01 has the capability of produced CLA when is inoculated to silage.