Actinobacterial Diversity Of The Terrestrial And Intertidal Zone Of The King George Island At The Western Antarctic

King George Island is located in the low latitude region of western Antarctic. The ecological environment and biological communities there are sensitive to regional or global climate change which makes it the ideal place to the research work of the terrestrial and nearshore ecosystems of the South Pole. As a large group of microorganisms, actinobacteria in the Antarctic may form unique adaption model and molecular regulation mechanism to produce novelty and diversity of species and huge potential application ability during their long term adaption to this special geographical environment. It makes the actinobacteria in the Antarctic an important research hotspot which draws great attention from microbiology researchers. In this paper, we used PCR-DGGE,16S rDNA clone library and culture-dependent methods to study the actinobacterial diversity of the soil and intertidal zone sediment of the King George Island at the South Pole. The study will lay the foundation for the utilization of the unique actinobacterial resourses of the Antarctic.Firstly, PCR-DGGE method was used to analyze the diversity and community structure of the actinobacteria of 12 samples collected from the land and intertidal zone of the King George Island at the South Pole. The DGGE profiles and the sequencing results showed that the soil and intertidal zone sediment of the King George Island contain rich resources of actinomycetes, and the diversity of the actinobacteria in the land soil is higher than that in the intertidal zone sediment. The sequencing results also showed that the 30 bands of the 6 soil samples distributed in 10 Orders and 15 Famililies of Class Actinobacteria, Acidimicrobiia and Coriobacteriia. Pseudonocardiaceae is the dominant group of the land soil samples. The 14 bands of the 6 intertidal zone samples distributed in 5 Orders and 5 Famililies of Class Actinobacteria and Acidimicrobiia and Demequinaceae is the dominant group of this area.Four actinobacterial-specific 16S rDNA clone libraries were constructed to analyze the diversity and community structure of actinomycetes of the 12 samples furtherly. The sequencing results also supported that there were higher actinobacterial diversity in the soil samples than that in the intertidal zone sediment. The two actinobacterial-specific 16S rDNA clone libraries of the soil samples all distributed in Class Actinobacteria and Acidimicrobiia. There were a total number of 10 Orders and 19 Families in the 6 soil samples, and Actinobacteria is the dominant group. The two 16S rDNA clone libraries of the intertidal zone sediment samples distributed in 8 Orders and 14 Families of Class Actinobacteria and Acidimicrobiia. The actinomycetes in the mixed samples of E5 and E8 distributed in 5 Orders and 8 Families; while the actinomycetes in the mixed samples of El, Ell, W3 and W4 distributed in 7 Orders and 13 Families. Acidimicrobiia was the dominant group of the 2 libraries. The N-J phylogenetic tree showed that many sequences of the 4 libraries formed independent branches and had a long genetic distance with known species sequences. It indicated that the soil and intertidal zone sediment of the King George Island contained a lot of new taxonomic groups and the species and community structure of actinomycetes are abundant and diverse.11 selective media were used to isolate actinomycetes strains from 17 land soil samples and 13 intertidal zone sediment samples of the King George Island and 234 strains were obtained. According to the morphological characteristics and cultural features, some representative strains were selected to sequence the 16S rDNA. Sequence analysis and blast results showed that these strains belong to 5 different orders,10 different generas and 25 different species. The 10 different generas were Streplomyces, Arthrobacter, Nocardiopsis, Tsukamurella, Arthrobacter, Pseudonocardia, Microbacterium, Nesterenkonia, Kocuria and Mircrococcus. The 143 strains isolated from the 17 land soil samples belong to 7 generas and 17 species of Actinobacteria while the 91 strains isolated from the 13 intertidal zone sediment samples belong to 5 generas and 10 species of Actinobacteria. The results of the culture-dependent method also showed that the soil samples and intertidal zone sediment samples of the King George Island at the South Pole contain rich resources of actinomycetes, and the diversity of the actinomycetes in the soil samples is higher than that in the intertidal zone sediment samples.