鸽源益生菌的分离鉴定及其生物学特性研究OA

[Objective]This experiment was conducted to screen out pigeon-derived probiotics with potential applications,and to enrich the microecological prevention and control strategies in poultry.In this study,probiotic strains were isolated and identified from healthy pigeons,and the probiotic properties were systematically evaluated.[Method]Using cloacal contents samples collected from healthy pigeons,bacterial strains were isolated and subsequently identified through morphological observation,16S rDNA amplification,and phylogenetic tree analysis.The isolated strains were further subjected to comprehensive functional evaluation,including in vitro antimicrobial activity,characterization of antimicrobial substances,growth characteristics,tolerance properties,and safety assessment.[Result]Two bacterial strains were isolated from ten cloacal contents samples.Both stains were blue-violet,rod-shaped,Gram-positive bacteria and were designated as M1 and M2,respectively.Amplification of the 16S rDNA yielded specific fragments of approximately 1 500 bp,showing 99.93%sequence similarity to the corresponding reference strains.Phylogenetic analysis revealed that strain M1 clustered with Lactobacillus ingluviei,while strain M2 clustered with Limosilactobacillus reuteri.Compared with the MRS control,both isolates exhibited significant inhibitory activity against Escherichia coli and Salmonella(inhibition zone diameter>20.50 mm,P<0.05),with strain M2 showing a stronger inhibitory effect against Salmonella.Analysis of antibacterial substances revealed that,compared with untreated cell-free supernatants(CFS),the antimicrobial activity of strain M1 was extremely significantly reduced after adjustment of the CFS pH to 7.0(P<0.01).The antimicrobial activity of strain M2 CFS was significantly decreased after treatment with proteinase K(P<0.05).In terms of growth characteristics,both strains exhibited an S-shaped growth curve and possessed strong acid-producing ability.Tolerance tests showed that strain M1 had a higher survival rate in 0.3%bile salt solution(>90%),and strain M2 had a higher survival rate in 0.2%bile salt solution(>90%).Both isolates demonstrated high survival rate in simulated intestinal fluid(both>85%),but low survival rate in simulated gastric fluid(both<30%).In addition,strain M2 showed better heat resistance than strain M1.Safety testing showed that both isolated strains exhibited γ-hemolytic and were sensitive to commonly used antibacterial drugs such as amoxicillin,erythromycin,and gentamicin.[Conclusion]In this study,two strains were isolated and identified from the cloaca of healthy pigeons,namely Lactobacillus ingluviei and Limosilactobacillus reuteri.Both strains exhibited strong antagonistic activity against pathogenic bacteria,notable tolerance to adverse environmental conditions,and favorable safety profiles.Among them,strain M2 demonstrated superior overall performance,indicating its potential as a promising probiotic candidate for pigeons.These findings provided valuable microbial resources for the maintenance of intestinal health and the development of probiotic preparations in pigeons.