Selective Isolation Of Microbispora From Rhizhosphere Soil Of 23 Different Mangrove Plants

Microbispora is a genus of actinomycete under the family of Streptosporangiaceae.In order to selectively isolate Microbispora and to understand their geographically distribution in mangrove soil,23 samples of rhizosphere soil of different mangrove plants were collected from Touyuan,Wenchang,ChinaAfter pretreatments of dry heat(100℃,60 min or 120℃,60 min) and treatment with Chloramine-T(1%,30 min at room temperature) for each sample,100μL of the 10^-1 to 10^-3 dilutions of the resultant suspensions were transferred and spread onto the selective isolation media.GA and HV media were employed as the isolation media that supplemented with 0.5 mg/L multi-vitamin,50 mg/L cycloheximide,50 mg/L nystatin and 50 -100 mg/L K₂Cr₂O₇. One hundred and ninety nine actinomycetes including 136 Streptomyces-like isolates and 63 non-Streptomyces-like isolates were isolated according to their morphology on agar plates and under microscope.Seven Streptomyces- like isolates and 28 non-Streptomyces-like isolates were putatively identified to genus level based on 16S rRNA gene sequence analysis,which belong to Microbispora(19),Streptomyces(7),Nonomuraea(4),Micromonospora(2), Streptosporangium(1),Asanoa(1) and one uncertain genus under Micromonosporaceae. Isolates 211020 and 212030 maybe two new members of Microbispora;isolate 210121 maybe a new species of Asanoa;isolate 210417,and isolates 210432,212202 maybe two new species belong to Nonomuraea;and isolate 211018 maybe a new genus of Micromonosporaceae.Bioactivities detection of these 199 strains resulted that 64 strains showed bioactivities including 1 strain active against Caspases-3,9 strains active against HCT-116,39 strains active against SMMC-7721 cell,15 strains active against Staphyloccocus aureus ATCC 51650, 9 strains active against MASR,and 7 strains active on inhibition of PTP1B,a kind of protein related with diabetes.Furthermore,Microbispora sp.212030 shows two activities against Caspases-3 and S.aureus ATCC 51650.According to all the results above,it is concluded that pretreatments of dry heat(120℃, 60 min) and treatment with Chloramine-T(1%,30 min at room temperature) offer a good selection and GA is better than HV for the isolation of Microbispora from mangrove soil. Total of 26 Microbispora strains have been isolated from 6 rhizosphere soils of different mangrove plants,which including two new species.