Construction Of Transgenic Lactobacillus With Xylanase Activity And Its Application As A Feed Additive On Broilers

With the increasing of population, people’s living standard has improved, and meatconsumption demand increases rapidly. At the same time, people put forward higherrequirements for meat quality. In this case, the animal husbandry of China will inevitablydevelop rapidly, which makes serious contradictions between the lack of energy feed andmatched feed industry development of our country. It is a good study way that how toimprove the grain feed utilization which rich in non-starch polysaccharides. As an importantnon-starch polysaccharide degrading enzyme, xylanase has become an important research athome and abroad. Lactic acid bacteria as a probiotic is widely used to replace antibiotics,which has promoted intestinal balance, prevented diarrhea, strengthened the host health,improved immunity, and reduced blood cholesterol. If we can put different sources ofxylanase genes into advantage bacterium group of animals intestinal, and make it hydrolyzexylan, we can achieve the goal of long-term, stable and cheap. This study by cloning havingefficient non-starch polysaccharide degradation ability of Bacillus subtilis xylanase gene,constructing lactic acid bacteria xylanase gene engineering bacteria, making the xylanasegene expression in the lactic acid bacteria. By adding the bacteria in the liquid water, it mightgrow in intestinal tract of broilers. Growth performance, carcass characteristics, meat quality,blood biochemical indicators, immune organ index of broilers were studied, which wouldoffer a new approach for animals using non-starch polysaccharides effectively, providingtheoretical basis including improving broilers performance and immune response. Theexperiment was carried out as follows.（1）Xylanase genes xynA were cloned from the bacterium chromosome DNA byspecial primers. It was561bp encoding187amino acids, and belong the members of thexylanase hydrolysate family. Lactobacillus reuteri XNY which containing xylanase gene wasconstructed using molecular gene clone technology. Through the culture supernatant proteinsof L. reuteri XYN transformants were analyzed by SDS-PAGE and plate test for xylanaseactivity of L. reuteri XYN transformants, it was proved that the Lactobacillus reuteri XNYwhich containing xylanase gene would produce xylanase.（2）Two hundred and forty one-day-old broilers were randomly divided into3 treatments, with4replicates of20broilers in each. Three treatments were fed with clear water,bacterial solution of lactobacillus and xylanase-producing lactobacillus. The effects ofxylanase-producing lactobacillus on growth performance, carcass characteristics, meat quality,blood biochemical indicators, immune organ index were studied in broilers. The resultsshowed that treatment with xylanase-producing lactobacillus had no significant impact onbroiler performance and slaughter performance during the early and later stages (P>0.05), butit could significantly improve the chest muscle rate(P<0.05). It could significantly improvethe pH45min(P<0.05), drip loss and shear force were decreased markedly(P<0.05). The bursaof fabricius index in broilers immune organs(P<0.05) was also improved. The contents ofblood globulin and glucose were increased, and blood uric acid, triglycerides and totalcholesterol were decreased markedly(P<0.05). Through added xylanase-producinglactobacillus to drinking water could improve carcass characteristics, immunity response,accelerate protein metabolism and the deposition in the body of broilers.In the study, xylanase gene xynA of bacillus subtilis WL001was successfully cloned,and built xylanase-producing lactobacillus. Using it as a feed additive, it had no significantimpact on growth performance, however, it could significantly improve the immuneperformance of broilers.