Microbial Community Structure Characteristics Of Ringworm Of The Body And Discovery Of Antifungal Probiotics

The purpose of this study was to explore the succession rule of the microbial community structure in ringworm of the body;Aiming at two common pathogenic fungi,Trichophyton rubrum and Candida albicans,the best antifungal strains were screened out by using the probiotics preserved in our laboratory,their antibacterial mechanism and antibacterial substances produced were explored,and the sensitivity of antifungal drugs was tested in vitro.So as to provide a theoretical basis for better diagnosis and treatment of skin diseases.To this end,this study was carried out from the following aspects:At first,high-throughput sequencing technology was used to study the characteristics of bacterial and fungal communities on the skin lesions areas of skin surface and 3 cm away from the skin lesions areas(adjacent to the skin lesions areas)to understand their succession rules.The total genomic DNA was extracted from 50 dander samples collected from the affected sites and the adjacent sites of 25 patients with skin diseases in the First People’s Hospital of Yunnan Province,and the target fragments were amplified and sequenced.The results showed that about 98% of the sequences belong to Actinobacteria,Firmicutes and proteobacteria in the taxonomic level of the phylum.At the taxonomic level of genus,there were similarities in species and differences in the number of bacterial community structures in samples of skin lesions areas and adjacent areas.Pseudomonas,Corynebacterium and Staphylococus were the top three bacterial genera in relative abundance.The difference was that Lactobacillus was relatively more abundant in the adjacent to the skin lesions areas than in the skin lesions areas.The fungal colony structure of all the samples were also similar,about 97% of the sequences belonged to Basidiomycota and Ascomycota.At the taxonomic level of genus,the fungal community structure of the skin lesions areas and adjacent samples also had the same dominant flora,the most abundant two genera were Cryptococcus and Trichophyton,the relative abundance of Cryptococcus in the skin lesions and adjacent areas were 51.0% and 50.1%,respectively;the relative abundance of Trichophyton in the skin lesions and adjacent areas were 23.7% and 17.9%,respectively.The difference was that Candida albicans was more abundant in the skin lesions areas than adjacent areas,while Malassezia was the opposite.By identifying the bacterial and fungal communities on the skin surface of patients with skin diseases,it would lay a foundation for the identification of microbial communities under skin diseases or damage of barrier structure.Lactic acid bacteria can secrete a variety of antimicrobial substances,which can effectively inhibit the growth and reproduction of pathogenic microorganism.In this study,through fungal culture and identification,aiming at Trichophyton rubrum and Candida albicans,a probiotic strain with the best antifungal effect was screened out by using the probiotic library independently established by our laboratory.The results were all Lactobacillus plantarum YM-4-3,which was fermented to explore its antimicrobial mechanism against Trichophyton rubrum.Through scanning electron microscopy and transmission electron microscopy observation,it was found that the antimicrobial substance destroyed the cell wall and cell membrane of Trichophyton rubrum.In order to more accurately understand the bacteriostatic effect of Lactobacillus plantarum YM-4-3 against Candida albicans under salt stress,the two were co-cultured in liquid,and the bacteriostatic real-time monitoring of Candida albicans was carried out for 48 h.The results showed that the bacteriostatic effect was the best in MRS broth medium with 2.0% Na Cl.After co-culture for 12 h,the p H values from small to large was: 2.0% Na Cl < 0.9% Na Cl < 0.0% Na Cl < 3.0% Na Cl.Subsequently,the chemical nature of antimicrobial substances was discussed,and it was found that they were mainly organic acids,bacteriocins,etc.,and which were not resistant to high temperature.The difference of bacteriocin expression under different salt concentrations was detected by q PCR technology,and the effect of bacteriocin on the antimicrobial effect under salt stress was explored.Lactobacillus plantarum YM-4-3 strain and Candida albicans were co-cultured in MRS broth medium containing 0.0%-3.0% Na Cl.Lactobacillus plantarum YM-4-3 was induced by Na Cl after 36 hours of culture.From the transcriptome level,It was found that the expression of bacteriocin related genes of Lactobacillus plantarum YM-4-3 was generally increased in MRS broth medium containing 2.0% Na Cl.Finally,we used microdilution method to evaluate the antifungal effects in vitro of six common antifungal drugs and four probiotic fermented supernatant concentrates at different salt concentrations,and the therapeutic effect and the possibility of clinical application were discussed,so as to lay a theoretical foundation for solving problems such as adverse drug reactions and fungal drug resistance in traditional drug therapy.The results of drug sensitivity test showed that ketoconazole and terbinafine had obvious inhibitory effect on Trichophyton rubrum;Candida albicans was sensitive to amphotericin B.Fermentation supernatant concentration with salt reduced the bacteriostatic effect,and the minimum inhibitory concentration of the fermentation supernatant concentration was higher,but the bacteriostatic effect was obvious,and it had bacteriostatic effect on Trichophyton rubrum and Candida albicans.