Diversity Of Micromonosporaceae From Mangrove Soil In Bamen Bay

Micromonosporaceae is the main source of novel antibiotic, and it has been attracting worldwide attention; mangroves are special habitats where huge amount of Actinomycetes resources exist. Mangrove microbes are not only abundantly diverse, but with functions totally distinct with the terrestrial ones and most of them are verified as undiscovered or uncultured. High-throughput sequencing is a convenient method with high speed, long length and high specificity. By High-throughput sequencing we evaluated the diversity of Actinomycetes in mangrove soil, and then isolated the dominant group Micromonosporaceae by traditional isolation method to study the diversity of Micromonosporaceae in mangrove soil and their interaction with environment.High-throughput sequencing was carried out to study the diversity of actinomycetes from various habitats (intertidal zone, Xylocarpus mekongensis, bruguiera sexangula and land), the result revealed that although the quantity of high-throughput sequencing data is great enough, this study still failed to cover the whole microbial community (Coverage88%-91%), and large amount of unidentified and uncultured microbial groups still exist.12groups at order level were detected (Frankiales, Corynebacteriales, Micromonosporales, Propionibacteriales and Pseudonocardiales account for over80%of total number),25at family level (Acidothermaceae, Micromonosporaceae, Mycobacteriaceae, Nocardioidaceae, Pseudonocardiaceae, Streptomycetaceae, Frankiaceae, Propionibacteriaceae, Microbacteriaceae, Kineosporiaceae occupied for over80%of total number).The sequence analysis result revealed that the diversity index and the relative abundance of actinomycetes were distinct among various samples, and similar diversity existed in two types of mangroves, except for Elev-16S-976group was detected in Xylocarpus mekongensis, rest of the groups revealed similar levels in two mangroves samples. Frankiales takes the major proportion on the overall number (average33.9%), especially in land sample (49.8%), but in the intertidal zone sample, the proportion of Corynebacteriales is higher than other groups, and the proportion of Frankiales was lower than other samples. In the study of the diversity in Micromonosporaceae at genus level,9genera were detected in this study (Micromonospora, Luedemannella, Actinoplcmes, Dactylosporangium, Planosporangium, Longispora, Catelliglobosispora, Actinocatenispora and Hamadaea), and Micromonospora took the largest proportion of total number (average16%), from high to low proportion in different habitat was intertidal> Xylocarpus mekongensis>bruguiera sexangula>land, Actinoplanes> Dactylosporangiu and Planosporangium took a relatively lower abundance than Micromonospora. The microbial diversity of intertidal zone was lower than which in mangroves and land. There were only two genus detected in intertidal sample: Micromonospora (66.7%) and Luedemannella (33.3%). Micromonospora took the largest proportion in the mangroves samples (average40%), Luedemannella (average25%) was detected slightly fewer than Micromonospora, and Actinoplanes took the main proportion in the land sample (40%).The plate dilute method, four pre-treatment methods and five media with antibiotics were utilized to isolate Micromonosporaceae from samples of intertidal zone, two mangroves (Xylocarpus mekongensis and bruguiera sexangula) and land habitats.295strains were isolated from three samples. After eliminating repetitive strains by morphological characteristics,115strains were carried out with16S rDNA sequencing and105strains were identified belong to Micromonosporaceae. Most of the strains were incubated from HV agar with air-dried samples pre-processed in55℃water baths. According to the16S rDNA sequence analysis,105strains were preliminarily identified with21groups at species level, the largest similarities between strains and type strains spread from98.5%to100%, and29.5%of the strains’similarities were under99%with type strains. The105strains were distributed over three genus:Micromonospora, Jishengella and Verrucosispora, and Micromonospora took the largest proportion (85%). The amount of isolated trains spread in descending order of Mangrove sample>intertidal sample>land sample.