Marininema halotolerans sp. nov., a novel thermoactinomycete isolated from a sediment sample, and emended description of the genus Marininema Li et al. 2012.

A novel Gram-stain-positive bacterium, designated strain YIM M11385(T), was isolated from a marine sediment sample collected from the South Bay, Little Andaman Island, India with a salinity of 35 p.p.m., pH 8.5. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM M11385(T) belongs to the genus Marininema, supported by a bootstrap value of 100 %. The taxonomic position of this organism was further established by using a polyphasic approach. Strain YIM M11385(T) grew optimally at 28 °C, pH 7.0 and in the presence of 0-5 % (w/v) NaCl. The 16S rRNA gene sequence similarity between strain YIM M11385(T) and Marininema mesophilum SCSIO 10219(T) was 98.3 %. Strain YIM M11385(T) exhibited a quinone system with only MK-7, the polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as major components, and the major fatty acids were anteiso-C15 : 0, iso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The level of DNA-DNA relatedness between strain YIM M11385(T) and M. mesophilum SCSIO 10219(T) was 59.36 %. On the basis of genotypic and phenotypic data, it is apparent that strain YIM M11385(T) represents a novel species of the genus Marininema, for which the name Marininema halotolerans sp. nov. is proposed. The type strain is YIM M11385(T) ( = CCTCC AB 2012052(T) = DSM 45789(T)). In addition, we propose that the description of the genus Marininema should be further emended based on the results of the present study.

Saccharomonospora oceani sp. nov. isolated from marine sediments in Little Andaman, India.

Two actinomycete strains, designated YIM M11168(T) and YIM M11177, were isolated from marine sediment samples from Little Andaman, Indian Ocean, and their taxonomic position was determined by a polyphasic approach. The two Gram-positive, aerobic strains were observed to produce branched substrate mycelium and aerial hyphae but did not fragment, and no diffusible pigment was produced on the media tested. At maturity, spores were formed singly or in pairs on aerial hyphae and substrate mycelium, and occasionally the single ones were borne on long sporophores. The optimum growth was determined to occur at 28 °C, 0-4 % (w/v) NaCl and pH 7.0-8.0. Whole-cell hydrolysates of both strains contained meso-diaminopimelic acid and the diagnostic sugars were determined to be galactose, glucose and arabinose. Their predominant menaquinone was found to be MK-9(H4). The polar lipids detected in the two strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, phosphatidylmethylethanolamine, phosphatidylethanolamine and two unknown phosphoglycolipids. The major fatty acids (>10 %) identified were iso-C16:0, iso-C16:1 H, iso-C16:0, C17:1 ω6c for strain YIM M11168(T), iso-C16:0 and Summed Feature 3 for strain YIM M11177. The G + C contents of the genomic DNAs of both strains were determined to be 71.4 %. DNA-DNA hybridization relatedness values (78.4 ± 3.7 %) of these two isolates supported the conclusion that they belong to the same species. Based on phylogenetic analysis, phenotypic and genotypic data, it is concluded that the two isolates belong to a novel species of the genus Saccharomonospora of the family Pseudonocardiaceae. The name Saccharomonospora oceani sp. nov. (Type strain YIM M11168(T) = DSM 45700(T) = JCM 18128(T)) is proposed for the novel species.

Actinomadura sediminis sp. nov., a marine actinomycete isolated from mangrove sediment.

In this study, the taxonomic position of an actinobacterium, strain YIM M 10931(T), which was isolated from a mangrove sediment sample collected in Dugong Creek, Little Andaman, India, was determined by a polyphasic approach. This gram-positive, aerobic strain produced branched substrate mycelium and aerial hyphae, which differentiated into short, hooked or spiral spore chains. The organism contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The whole cell sugars consisted of mannose, ribose, glucose, galactose and madurose. The cellular fatty acid profile mainly consisted of iso-C(16 : 0), 10-methyl C(18 : 0) and C(16 : 0). The quinone system was predominantly composed of MK-9(H(8)) (45.5 %) and MK-9(H(6)) (39 %). The phospholipids detected were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol and two unknown phospholipids. The organism showed a combination of morphological and chemotaxonomic properties typical of members of the genus Actinomadura. Moreover, phylogenetic analysis based on a 16S rRNA gene sequence generated from the strain identified its closest relatives as Actinomadura cremea DSM 43676(T) (98.4 % sequence similarity), Actinomadura rifamycini DSM 43936(T) (97.4 %) and Actinomadura apis IM17-1(T) (96.9 %). It was obvious from the resulting phylogenetic trees that strain YIM M 10931(T) belongs to a distinct subclade within the evolutionary radiation of the genus Actinomadura. DNA-DNA hybridizations of strain YIM M 10931(T) with A. cremea DSM 43676(T) and A. rifamycini DSM 43936(T) were performed and further confirmed that the isolate represents a separate genomic species. Based on the phenotypic and genotypic characteristics presented, it is proposed that strain YIM M 10931(T) represents a novel species within the genus Actinomadura, for which the name Actinomadura sediminis sp. nov. is proposed; the type strain is YIM M 10931(T) ( = CCTCC AA 2010009(T) = DSM 45500(T)).

Partial purification and anti-leukemic activity of L-asparaginase enzyme of the actinomycete strain LA-29 isolated from the estuarine fish, Mugil cephalus (Linn.).

The actinomycete strain LA-29 isolated from the gut contents of the fish, Mugil cephalus of the Vellar estuary showed excellent L-asparaginase activity The enzyme was purified 18-fold and the final recovery of protein was 1.9%, which exhibited an activity of 13.57 IU/mg protein. The partially purified L-asparaginase inhibited the growth of leukemia cells in male wistar rats. Average survival period of the rats was more in an optimum enzyme dose of 100 units and the survival period was less when the dosages were increased and at the same time the enzyme became less effective when the dosages were decreased. Higher survival of 17.2 days was recorded when 100 units of the enzyme was given in three intermittent doses (50/25/25 units) at the interval of 24 hr. Analysis of cell components of the strain LA-29 has revealed the wall type-I which is the characteristic of the genus Streptomyces. Further the morphological, physiological and biochemical features along with the micromorphological results obtained for the strain LA-29 were compared with that of the Streptomyces species found in Bergey's Manual of Determinative Bacteriology and the strain LA-29 has been tentatively identified as Streptomyces canus.

Research on marine actinobacteria in India.

Marine actinobacteriology is one of the major emerging areas of research in tropics. Marine actinobacteria occur on the sediments and in water and also other biomass (mangrove) and substrates (animal). These organisms are gaining importance not only for their taxonomic and ecological perspectives, but also for their unique metabolites and enzymes. Many earlier studies on these organisms were confined only to the temperate regions. In tropical environment, investigations on them have gained importance only in the last two decades. So far, from the Indian peninsula, 41 species of actinobacteria belonging to 8 genera have been recorded. The genus, Streptomyces of marine origin has been more frequently recorded. Of 9 maritime states of India, only 4 have been extensively covered for the study of marine actinobacteria. Most of the studies conducted pertain to isolation, identification and maintenance of these organisms in different culture media. Further, attention has been focused on studying their antagonistic properties against different pathogens. Their biotechnological potentials are yet to be fully explored.