Aerobic Microbial Flora Of Silkworm Gut Micro-ecological Environment Regulation

Recently, developing with microecology, a lot of microecologics have sprung out and taken effect on improving animal feed efficiency and disease prevention and cure. However, the leaf-silk effect is still low and the occurrence rate of disease is also high. That has increased more cost of sericultural production. Besides genetic improvement of variety and rearing management, the regulation and improvement on microenvironment of intestine of silkworm is another important ways. So the study on microbe in intestine of silkworm and the improvement on microenvironment in intestine have important meaning in theory and practice. The paper have had a systematic studies on microbial composition and fluctuation of the normal microflora in intestine of 揦ia Fang?pure race in different period and instar, on changing microecsystem in intestine by feeding cellulose-decomposing bacteria, and investigated the cellulose-decomposing bacteria in intestine of silkworm of different varieties I. The studies on the obligate aerobes and facultative anaerobe in intestine of silkworm of 揦ia Fang?race Under no microbe condition, we get the midgut liquid of spring and autumn silkworm of mulberry leaf rearing and artificial diet rearing in different stadia, then dilute them into one thousand and ten thousand, separate the obligate aerobes and the facultative aerobes by normal and several selecting media. Being tentatively identified, they are belongs to twelve genera. The statistical results have shown that the microbial composition in intestine of silkworm has been affected by diet greatly. The species and quantity change greatly with different stadia. The microbial composition is more complicate and the quantity is more in young larva stage than in grown silkworm stage, in spring rearing season than in autumn rearing season and artificial diet rearing. The normal microbe is micrococcus and bacillus in intestine. In spring rearing season, the microbial quantity in intestine of second instar silkworm is most, then third instar silkworm, less microbe in first, fourth and fifth instar silkworm. Enterobacteria, micrococcus and bacillus occupy the dominant position. The things are detailed as follow: In intestine of first instar silkworm, there has small quantity of microbe and most of microorganism is enterobacteria. In second instar, the total of microbion increase rapidly and a lot of III 9 I enterobactcria, micr~coccus and bacillus are found. In third stadium, micrococcus and enterobacteria are the dominant part. In fourth and fifth stadiwn, a few of microbe are discovered. In fifth stadium, bacillus increases a little. Some enterobacteria and micrococcus are discovered. In autumn rearing season, there have a little microbe from first instar to fifth instar. Relatively speaking, the microbial quantity in intestine of second itutar silkworm is most, then first instar silkworm. Except in second stadium, micrococcus is not discovered. Much bacillus exists in intestine of frst instar silkworm and it keeps a small quantity in other stadium. In intestine of artificial diet rearing silkworm, bacillus and micrococcus are the dominant part, keep at the level of 106 every gram of intestinal juice or so. However, little enterobacteria are discovered. 2. The study of cellulose-decomposing bacteria in intestine of silkworm We have separated, the cellulose-deco...