ABSTRACT. Fifty-seven proteobacterium species were successfully isolated from soils of Barrientos Island of the Antarctic using 11 different isolation media. Analysis of 16S rDNA sequencing of these isolates showed that they belonged to eight different genera, namely Bradyrhizobium, Sphingomonas, Methylobacterium, Caulobacter, Paracoccus, Ralstonia, Rhizobium, and Staphylococcus. All isolates were studied for capability of producing antimicrobial and antifungal secondary metabolites using high-throughput screening models. Approximately 23 (13/57) and 2% (1/57) of isolates inhibited growth of Candida albicans ATCC 10231 T and Staphylococcus aureus ATCC 51650 T , respectively. These results indicated that proteobacterium species isolates from Antarctic could serve as potential source of useful bioactive metabolites. Enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting produced nine clusters and 13 single isolates, with a high D value of 0.9248. RAPD fingerprinting produced six clusters and 13 single isolates, with a relatively low D value of 0.7776. ERIC-PCR analysis proved to have better discrimination capability than RAPD analysis and generated better clustering for all proteobacterium species isolates. We conclude that ERIC-PCR is a robust, reliable and rapid molecular typing method for discriminating different genera of proteobacteria.

An actinomycete, strain 2602GPT1-05 T , was isolated from a composite mangrove soil sample collected from Wenchang, Hainan province, China. Strain 2602GPT1-05 T showed closest 16S rRNA gene sequence similarity to Micromonospora haikouensis 232617 T (99.05 %), and phylogenetically clustered with Micromonospora haikouensis 232617 T , Micromonospora matsumotoense IMSNU 22003 T (98.7 %) and Micromonospora rifamycinica AM105 T (98.6 %) based on the 16S rRNA and gyrB gene sequence phylogenetic analysis. The strain harboured meso-DAP and glycine as major cell-wall amino acids, and MK-10(H 6 ) and MK-9(H 6 ) as predominant menaquinones. The characteristic whole-cell sugars were xylose, arabinose, glucose and galactose. The polar lipid profile comprised phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylglycerol, phosphatidylinositol mannosides, unknown phospholipid and an unknown phosphoglycolipid. The major cellular fatty acids were C 18 : 1 v9c, iso-C 15 : 0 , 10-methyl C 18 : 0 (tuberculostearic acid), C 16 : 0 , C 18 : 0 and iso-C 16 : 0 . The DNA G+C content was 71.7 mol%. Furthermore, some physiological and biochemical properties and low DNA-DNA relatedness values enabled the strain to be differentiated from members of closely related species. On the basis of these phenotypic, genotypic and chemotaxonomic data, strain 2602GPT1-05 T represents a novel species of the genus Micromonospora, for which the name Micromonospora wenchangensis sp. nov. is proposed. The type strain is 2602GPT1-05 T (5CCTCC AA 2012002 T 5DSM 45709 T ).

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A bacterial strain, designated M26(T), was isolated from a fish gastrointestinal tract, collected from Zhanjiang Port, South China. 16S rRNA gene sequence analysis indicated that strain M26(T) belongs to the subclass α-Proteobacteria, being related to the genus Paracoccus, and sharing highest sequence similarity with Paracoccus alcaliphilus JCM 7364(T) (98.1 %), Paracoccus huijuniae FLN-7(T) (97.3 %), Paracoccus stylophorae KTW-16(T) (97.1 %) and Paracoccus seriniphilus DSM 14827(T) (96.9 %). The major quinone was determined to be ubiquinone Q-10, with Q-9 and Q-8 as minor components. The major fatty acid was identified as C18:1ω7c, with smaller amounts of C18:0 and C16:0. The G+C content of the genomic DNA was determined to be 64.3 mol%. The DNA hybridization value between strain M26(T) and the most closely related type strain, P. alcaliphilus, was 29.0 ± 1.0 %. The results of physiological and biochemical tests and low DNA-DNA relatedness showed that the strain could be readily distinguished from closely related species. On the basis of these phenotypic and genotypic data, strain M26(T) is concluded to represent a novel species of the genus Paracoccus, for which the name Paracoccus siganidrum sp. nov. is proposed. The type strain is M26(T) (=CCTCC AB 2012865(T) = DSM 26381(T)).

A novel endophytic actinomycete, strain 274745 T , was isolated from a root of Sonneratia apetala collected in a mangrove forest in Sanya, Hainan province, China. The 16S rRNA gene sequence of strain 274745T showed the greatest similarity to Micromonospora pattaloongensis TJ2-2 T (98.3 %). Phylogenetic analysis based on the gyrB gene also supported the close relationship of these two strains. The predominant menaquinone was MK-10(H 8 ) and the major fatty acids were iso-C 15 : 0 , C 17 : 0 and anteiso-C 15 : 0 . The characteristic whole-cell sugars were xylose and mannose. The cell wall contained meso-diaminopimelic acid and glycine. The polar lipid profile mainly comprised phosphatidylethanolamine, phosphatidylinositol and diphosphatidylglycerol. The DNA G+C content was 71.6 mol%. Furthermore, a combination of DNA-DNA relatedness and some physiological and biochemical properties indicated that the novel strain could be readily distinguished from the closest phylogenetic relatives. On the basis of these phenotypic and genotypic data, strain 274745 T represents a novel species of the genus Micromonospora, for which the name Micromonospora sonneratiae sp. nov. is proposed. The type strain is 274745 T (5CCTCC AA 2012003 T 5DSM 45704 T ).