Isolation and identification of Lactobacillus crispatus and evaluation of probiotic properties in vitro
Objective To isolate and screen Lactobacillus crispatus from healthy female vagina and evaluate its probiotic characteristics in vitro in order to provide a new strain for further screening and study of microecological agents for effective treatment of female reproductive system diseases.Methods The vaginal secretions of 10 healthy women were collected and screened in Department of Reproductive Medicine,the Second Affiliated Hospital of Naval Medical University from April 2023 to May 2023.Lactobacillus crispatus was identified by 16S rRNA sequence,and its growth characteristics,acid-producing ability,H2O2 producing ability and bacteriostatic ability were detected.Results Totally 39 strains of Lactobacillus crispatus were isolated and identified from 10 healthy women.The logarithmic growth phase of Lactobacillus crispatus was 10-40 h,among which Lactobacillus crispatus 4-5 and Lactobacillus crispatus 6-7 grew faster.The pH of Lactobacillus crispatus decreased rapidly within 8-24 h,and the pH of 48 h was stable between 3.89 and 4.05.Among them,Lactobacillus crispatus 6-6,6-7,6-9,6-11 had better acid production.All 10 strains of Lactobacillus crispatus could produce H2O2,and Lactobacillus crispatus 4-5,4-11,6-5 and 6-7 had better H2O2 production.Lactobacillus crispatus 6-5,6-7 and 6-9 had better inhibitory effect on Candida albicans,in which the diameters of bacteriostatic zone were(20.90±0.31)mm,(20.61±0.70)mm and(21.73±0.37)mm,respectively.Lactobacillus crispatus 4-5 and 6-7 had better inhibitory effect on Staphylococcus aureus.Among them,the diameters of bacteriostatic zone were(20.95±0.07)mm,(23.52±0.49)mm and(23.49±0.34)mm,respectively.Lactobacillus crispatus 6-5,6-6 and 6-7 had better inhibitory effect on Escherichia coli,the diameters of bacteriostatic zone were(19.03±0.23)mm,(18.20±0.18)mm and(18.55±0.29)mm,respectively.Conclusion Lactobacillus crispatus 6-5 and 6-7 have good acid production,hydrogen peroxide production,bacteriostatic activity and excellent biological characteristics,so they are expected to be candidate strains for the treatment of female reproductive system diseases.
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