Selection, Application And Studying On Biological Characteristics Of Antibacterial Lactobacilli

Lactobacilli is one of the preponderant flora in animal intestine and many articles have proved its benefits to host.For the time being,the studies of probiotics are almost concentrated on manufacturing and application effects,while the reports of the selection excellent bacteria properties, biological characteristics are poor.In this study,we obtained five Lactobacilli from intestinal material and fresh feces of health chickens,habits and pigs which grew very well and had typical colony and thalli.According to some key properties,for example the antagonistic activity against pathogenic bacteria of metabolite and the ability of the tolerance to acid,bile salts and phenol,Lactobacilli C2 strain was screened. Some fermentation qualities of the bacteria were studied. C2 strain was identified as Lactobacillus. Its active bacteria preparation can prevent and cure diarrhea efficiently by artificially E.coli through animal test.The study consist four main parts:Part Ⅰ: the selection of Lactobacilli that have antagonistic activity against pathogenic bacteria.Five Lactobacilli which can produce obvious ring of dissolving calcium were selected using MRS as medium from intestinal material and fresh feces of health chickens,habits and pigs.By the comprehensive analysis,for example the antagonistic activity against pathogenic bacteria of metabolite,the ability of tolerance to acid,bile salts and phenol,the curve of growth and PH change,thenumber of active bacteria in fermentation,Lactobacilli C2 strain from intestinal material of health chicken was selected finally.The high,middle sensitive rate of Lactobacilli C2 strain to pathogenic bacteria were 38.46,61.54% respectively. Lactobacilli C2 strain was tolerant to 0.4% bile salts and 0.4% phenol, and resistant to PH 3.0,4.0,5.0,while PH 2.0 exhibited strong inhibiting activity.The growth curve of C2 strain was:slow-moving period,accelerating period,logarithm growth period,decelerating period and invariable period were 1~2h, 2~4h, 4~10h, 10~14h and after 14h respectively.When in the invariable period of fermentation,the lowest PH of medium was 3.5.The optimum fermentation condition were:the optimum inoculation was 5%;the optimum temperature was 37℃;the optimum fermentation time was about 24h;the optimum PH range was 7-8.Fermentation way was no obvious influence.Part Ⅱ:the identification of Lactobacilli C2 strain.We identified Lactobacilli C2 strain from culture chatacter,bacterium outline as well as physiological and biochemical reaction,we also tried medicine sensitive test.According to Berges bacteriology identification and Anaerobic Bacterium and Infection, C2 strain was preliminary identified as Lactobacillus.Owing to the limitation of experiment condition and time,the species of Lactobacilli C2 strain was not further studied.Medicine sensitivity test indicated that C2 strain was sensitive to fifty percent of tested medicines.Comparing to standard bacterium,C2 strain had low sensitivity to some medicine.Part Ⅲ:the application of Lactobacilli C2 strain.(i)the preliminary experiment in curing diarrhea resulted by E.coli.Pathogenic E.coli contaminated healthy HaiLanBai chicks which have grown 27 days,within 24 hours,infection rate was 100%,After that,they were divided seven groups and diffrent Lactic Acid Bacteria preparation were used to cure infected chicks of experiment groups through flooding each chick.The curing time was 4 days,At the same time,the control guoup was guaranteedbasic drinking and eating.The results showed that,through three days curing,chicks of experiment groups had no death,diarrhea,and had good state expect one or two chicks.However ,the chicks of control group was dead in eighth day.Finally,the survive rate between experiment groups and control guoup had prominent difference(p<0.01),but among experiment groups it was not.Therefore ,Lactic Acid Bacteria preparation can cure diarrhea efficiently infected by E.coli.(ii)the comparison of lactobacilli,Bacillus Subtilis and antibiotics in curing chicks d...