Diversity Of Cultivable Streptomyces From Manganese-polluted Soil In Xiangtan City And Polyphasic Taxnomy Of Two Novel Species Of Streptomyces

Actinomycetes are a group of prokaryotic organisms belonging to Gram-positive bacteria and widely distributed in various environments.Actinomycetes,especially the members of the genus Streptomyces have received much attention from researchers due to their ability to produce the potential application of metabolites in medicine,food,industry,agriculture and other fields.It is reported that more than13600 kinds of bioactive secondary metabolites are produced by actinomycetes;while about 7600 produced by Streptomyces.During our experiments,over 1200 strains were isolated by the dilution-plate method on different medium from soils collected from the Xiangtan Manganese Mine?27°53'-28°03'N,112°45'-112°55'E?and its surrounding areas.According to the morphology,spore features and the 16S r RNA gene sequence,we obtained 51 strains of Streptomyces.Hence,a soil from manganese-polluted soil in Xiangtan city was rich in Streptomyces diversity.These preliminary findings indicated that these species?LUSFXJ,MKLv,MK 44,MK 45and MK 47?have a great potential as novel specials.In view of time,strain LUSFXJ and MK 44 were characterised by a polyphasic taxonomic approach.The results are as follow:?1?An actinomycete strain,designated strain LUSFXJ^T,was isolated from a soil sample obtained near the Xiangtan Manganese Mine,Central-South China and characterised using a polyphasic taxonomic approach.The 16S r RNA gene sequence-based phylogenetic analysis indicated that this strain belongs to the genus Strep tomyce s.The DNA-DNA relatedness between this strain and two closely related type strains,Streptomyces echinatus CGMCC 4.1642^T and Streptomyces lanatus CGMCC 4.137^T,were 28.7±0.4%and 19.9±2.0%,respectively,values which are far lower than the 70%threshold for the delineation of a novel prokaryotic species.The revealed that the menaquinones of strain LUSFXJ^T are MK-9?H₆?,MK-9?H₈?,MK-9?H₂?and MK-8?H₈?.The polar lipid profile of strain LUSFXJ^T was found to contain diphosphatidylglycerol and an unidentified polar lipid.The major cellular fatty acids were identified as iso-C_15:0,anteiso-C_15:0,iso-C_16:0,C_16:0 and Summed feature 3.Strain LUSFXJ^T was found to contain meso-diaminopimelic acid as the diagnostic cell wall diamino acid and the whole cell hydrolysates were found to be rich in ribose,mannose and glucose.Based on phenotypic,phylogenetic and chemotaxonomic characteristics,it is concluded that strain LUSFXJ^T represents a novel species of the genus Streptomyces,for which the name Streptomyces?2?An actinomycete strain,designated strain MK 44^T,was isolated from a soil sample obtained from the Xiangtan Manganese Mine,Central-South China and characterised using a polyphasic taxonomic approach.The 16S r RNA gene sequence-based phylogenetic analysis indicated that this strain belongs to the genus Strep tomyce s.Actually,strain MK 44 can be obviously different from other multiple streptomyes with>97.0%16S r RNA similarity according to morphological,cultural,chemotaxonomy characteristics and the 16S r RNA gene sequences.Therefore,strain MK 44^T belongs to a species of the genus Streptomyces,The DNA-DNA relatedness between this strain and speciali JCM 16611^T and S.mayteni JCM 16957^T,were30.90±0.28%and29.86±3.51%,respectively,values which are fa r lower than the 70%threshold for the delineation of a novel prokaryotic species.for which the name Strep tomyce s he lingen sis sp.nov.is proposed.So,strain MK 44 represents a novel species of the genus Streptomyces,for which the name Streptomyces helingensis sp.nov.is proposed.The type strain is MK 44^T?=GDMCC 4.137^T=KCTC 39920^T?.