P. D. Rekha

Microbacterium arthrosphaerae sp. nov., isolated from the faeces of the pill millipede Arthrosphaera magna Attems

A Gram-reaction-positive, rod-shaped bacterium, designated strain CC-VM-Y(T), was isolated from the faeces of the pill millipede Arthrosphaera magna Attems from India and was subsequently studied to determine its taxonomic position. Based on16S rRNA gene sequence similarities, the isolate clearly grouped with members of the genus Microbacterium. On the basis of pairwise comparisons of the 16S rRNA gene sequences, strain CC-VM-Y(T) was most closely related to Microbacterium insulae DS-66(T) (98 %), Microbacterium hydrocarbonoxydans DSM 160809(T) (97.8 %) and Microbacterium hominis NBRC 15708(T) (97.9 %). The peptidoglycan contained the amino acids ornithine (Orn), alanine (Ala), glycine (Gly), homoserine (Hsr) and glutamic acid (Glu) in an approximate molar ratio of 1.0 : 0.8 : 2.2 : 0.8 : 0.3. In addition, substantial amounts of threo-3-hydroxy glutamic acid (Hyg) were detected, which is characteristic of peptidoglycan type B2β. The acyl type of the peptidoglycan was glycolyl. The menaquinones of strain CC-VM-Y(T) were MK-13 (72 %), MK-12 (25 %) and MK-11 (3 %). The polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, one unknown phospholipid and one unknown glycolipid. The fatty acid profile comprised anteiso-C(15 : 0), iso-C(16 : 0) and anteiso-C(17 : 0) as the major fatty acids, which was congruent with fatty acid profiles of other members of the genus Microbacterium. The results of physiological and biochemical tests as well as DNA-DNA hybridizations with the most closely related species, M. insulae, M. hydrocarbonoxydans and M. hominis, revealed clear phenotypic and genotypic differences between strain CC-VM-Y(T) and other members of the genus Microbacterium. Based on these results, strain CC-VM-Y(T) ( = DSM 22421(T)  = CCM 7681(T)) represents a new species of the genus Microbacterium, for which the name Microbacterium arthrosphaerae sp. nov. is proposed.

Sphingomicrobium lutaoense gen. nov., sp. nov., isolated from a coastal hot spring

A yellowish pigmented, Gram-negative, rod-shaped, non-spore-forming bacterium (strain CC-TBT-3(T)), was isolated on marine agar 2216 from a coastal hot spring of Green Island (Lutao), located off Taituang, Taiwan. 16S rRNA gene sequence analysis of strain CC-TBT-3(T) showed a relatively low similarity (<95.5 %) to representatives of the genera Novosphingobium, Sphingosinicella and Sphingomonas of the Sphingomonadaceae, with the most related strain being the type strain of Novosphingobium soli. In addition to the relatively low 16S rRNA gene sequence similarity to members of established species, the isolate also showed some unique chemotaxonomic features, including the presence of some glycolipids with unusual chromatographic behaviour. The major components of the polar lipid profile were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid and three unidentified glycolipids. The major respiratory quinone was ubiquinone Q-10. The polyamine pattern was characterized by the triamine sym-homospermidine as a major component. Although the predominant fatty acids were C(18:1)ω7c and summed feature 3 (C(16:1)ω7c and/or iso-C(15:0) 2-OH), the isolate did not show the typical hydroxyl fatty acids, such as C(14:0) 2-OH, C(15:0) 2-OH and C(16:0) 2-OH, found in members of the genera Novosphingobium, Sphingomonas and Sphingosinicella, but showed instead high amounts of C(18:1) 2-OH (12.0 %). The DNA G+C content of strain CC-TBT-3(T) was 63.4 mol%. 16S rRNA gene sequence, chemotaxonomic and physiological analyses revealed that strain CC-TBT-3(T) represents a novel species in a new genus in the family Sphingomonadaceae for which the name Sphingomicrobium lutaoense gen. nov., sp. nov. is proposed; the type strain is of the type species S. lutoaense, CC-TBT-3(T) ( = DSM 24194(T) = CCM 7794(T)).

Lutaonella thermophila gen. nov., sp. nov., a moderately thermophilic member of the family Flavobacteriaceae isolated from a coastal hot spring

A yellow-pigmented, Gram-staining-negative, aerobic, non-motile, moderately thermophilic, rod-shaped bacterium, CC-MHSW-2T, was isolated from a coastal hot spring of Green Island (Lutao), located off Taituang, Taiwan. The 16S rRNA gene sequence analysis demonstrated that it shared <93.2% sequence similarity with Aquimarina species. The organism was unable to produce acid from carbohydrates, but it could utilize a number of organic acids and amino acids. Menaquinone 6 (MK-6) was the major respiratory quinone and iso-C15:0, iso-C17:0 3-OH and summed feature 3 (comprising C16:1omega7c and/or C16:1omega6c) were the predominant fatty acids. This fatty acid profile distinguished the isolate from members of the genera Aquimarina, Tamlana, Zhouia, Leeuwenhoekiella and Cellulophaga. The DNA G+C content of strain CC-MHSW-2T was 39.7+/-1 mol%. On the basis of the 16S rRNA gene sequence analysis and the chemotaxonomic and physiological data, strain CC-MHSW-2T represents a novel genus and species in the family Flavobacteriaceae, for which the name Lutaonella thermophila gen. nov., sp. nov. is proposed. The type strain is CC-MHSW-2T (=KCTC 22538T=JCM 15069T).

Supercritical carbon dioxide micronization of zeaxanthin from moderately thermophilic bacteria Muricauda lutaonensis CC-HSB-11T.

Moderately thermophilic bacterial strain CC-HSB-11(T) (Muricauda lutaonensis), which was described recently from a coastal hot spring of Green Island, Taiwan, has been identified to produce zeaxanthin as a predominant xanthophyll by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cell culture in bioreactor produced 3.12 ± 0.18 mg zeaxanthin L(-1) of culture. Micronization of zeaxanthin was achieved through supercritical carbon dioxide antisolvent precipitation method. Yield of zeaxanthin after the process was 53.4%. Dynamic light scattering assay determined the polydisperse existence of micronized particles of size 3 nm to 2 μm. Field emission scanning electron microscopy revealed distinct morphology and size distribution heterogeneity of particles. Integrity of zeaxanthin after the antisolvent process was assessed by LC-MS/MS. The technique capitalizes on the inherent ability of CC-HSB-11(T) to synthesize zeaxanthin and the work demonstrated feasibility of antisolvent precipitation method to produce microparticles exploiting a bacterial strain.

Virgibacillus soli sp. nov., isolated from mountain soil

A Gram-positive bacterium (strain CC-YMP-6(T)) was isolated from soil samples collected from Yang-Ming Mountain, Taiwan. On the basis of 16S rRNA gene sequence analysis, strain CC-YMP-6(T) clearly belonged to the genus Virgibacillus and was most closely related to the type strains of Virgibacillus halophilus (96.2 % similarity) and Virgibacillus kekensis (96.3 %). The predominant isoprenoid quinone was menaquinone MK-7 and the polar lipid profile was composed of the major components diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and one unidentified phospholipid plus moderate amounts of two unidentified aminophospholipids and a phospholipid. The polyamine pattern comprised spermidine as the single major component with spermine and putrescine present in minor amounts. The major fatty acids of strain CC-YMP-6(T) were iso-C(15 : 0) and anteiso-C(15 : 0). The results of physiological and biochemical tests allowed the clear phenotypic differentiation of strain CC-YMP-6(T) from all recognized species of the genus Virgibacillus. Strain CC-YMP-6(T) is therefore considered to represent a novel species of the genus Virgibacillus, for which the name Virgibacillus soli sp. nov. is proposed. The type strain is CC-YMP-6(T) (=DSM 22952(T)=CCM 7714(T)).

Versatile properties of an exopolysaccharide R-PS18 produced by Rhizobium sp. PRIM-18.

Exopolysaccharides (EPS) produced by bacteria have attracted scientific and industrial attention due to their multifunctional properties and relatively easier production. In this study, an EPS viz., R-PS18 produced by Rhizobium sp. PRIM-18 was characterized and its functional properties were assessed. Cell proliferative and in vitro wound healing activities of the EPS were established using human dermal fibroblast (HDF) cells. The isolate produced 2.1 g L(-1) purified EPS (molecular weight 9.33×10(6) Da) comprising of glucose, galactose, and mannose (6.1:1.8:1). Viscosity of 0.25% solution was 23.4 mPa s (shear rate 75 s(-1)) and it showed pseudoplastic and thixotropic behavior. High emulsification, iron chelation, and superoxide scavenging abilities were also observed. Significant increase in HDF cell proliferation and wound healing in vitro was achieved by R-PS18 treatment. Sulfation of R-PS18 significantly enhanced the cell proliferative and wound healing activities. In conclusion, these findings indicate potential applications of R-PS18.

Ruegeria intermedia sp. nov., a moderately thermophilic bacterium isolated from a coastal hot spring

A cream-coloured, Gram-negative, aerobic, non-motile moderately thermophilic, rod-to-irregular-shaped bacterium, CC-GIMAT-2(T), was isolated from a coastal hot spring of Green Island (Lutao), located off Taituang, Taiwan, on marine agar 2216. The 16S rRNA gene sequence analysis and subsequent comparisons showed that it was placed into the genus Ruegeria with 97.4 % similarity to Ruegeria lacuscaerulensis ITI-1157(T), and a lower sequence similarity to all other species of the genus Ruegeria. Reconstruction of phylogenetic trees indicated that strain CC-GIMAT-2(T) clustered within the genus Ruegeria. Robust tree topology for the genus Ruegeria including the new strain was only obtained by including all Rhodobacteraceae type strains but not if the analysis was limited to few selected taxa. The quinone system contained exclusively ubiquinone Q-10 and the fatty acid profile consisted mainly of C18 : 1ω7c, 11-methyl C18 : 1ω7c and C12 : 0 3-OH. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unidentified aminolipid. Other lipids were detected in moderate to minor amounts. The characteristic feature of the polyamine pattern was the predominant triamine spermidine. On the basis of the 16S rRNA gene sequence analysis and of the chemotaxonomic and physiological data, strain CC-GIMAT-2(T) represents a novel species of the genus Ruegeria, for which the name Ruegeria intermedia sp. nov. is proposed. The type strain is CC-GIMAT-2(T) ( = CCUG 59209(T) = LMG 25539(T) = CCM 7758(T)).

Microbacterium agarici sp. nov., Microbacterium humi sp. nov. and Microbacterium pseudoresistens sp. nov., isolated from the base of the mushroom Agaricus blazei

Three Gram-positive, rod-shaped bacteria (strains CC-SBCK-209( T), CC-12309(T) and CC-5209(T)) were isolated from the stalk of the edible mushroom Agaricus blazei grown in the laboratory. 16S rRNA gene sequence analysis indicated that all three isolates clearly belonged to the genus Microbacterium. Strains CC-SBCK-209( T) and CC-12309(T) were most related closely to the type strain of Microbacterium halotolerans (95.9 and 96.1 % 16S rRNA gene sequence similarity, respectively). These two novel strains shared 97.9 % 16S rRNA gene sequence similarity. Levels of similarity to the type strains of all other recognized Microbacterium species were lower than 95.5 %. The third strain (CC-5209( T)) showed the highest 16S rRNA gene sequence similarity to the type strain of Microbacterium resistens (97.6 %); levels of similarity to the type strains of all other recognized Microbacterium species were lower than 96 %. The quinone systems of strains CC-SBCK-209(T), CC-12309(T) and CC-5209(T) consisted of MK-11/MK-12, MK-11/MK-10 and MK-13 as major compounds, respectively. All three strains contained ornithine in their peptidoglycan. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unknown glycolipid. The polyamine pattern consisted of spermidine and spermine as predominant components. Fatty acid profiles (anteiso-C(15 : 0), iso-C(16 : 0) and anteiso-C(17 : 0 ) as major components) supported the affiliation of all three strains to the genus Microbacterium. The results of physiological and biochemical tests and DNA-DNA hybridization experiments allowed the clear phenotypic and genotypic differentiation of strains CC-SBCK-209(T) and CC-12309( T) from M. halotolerans and other closely related Microbacterium species. Strain CC-5209(T) could be differentiated clearly from M. resistens both genotypically and phenotypically. Based on these data, the novel strains are considered to represent three novel species of the genus Microbacterium. The names proposed for these organisms are Microbacterium agarici sp. nov. [type strain CC-SBCK-209( T) (=DSM 21798(T)=CCM 7686(T))], Microbacterium humi sp. nov. [type strain CC-12309(T) (=DSM 21799(T)=CCM 7687(T))] and Microbacterium pseudoresistens sp. nov. [type strain CC-5209(T) (=DSM 22185(T)=CCM 7688(T))].

Sulfated exopolysaccharide produced by Labrenzia sp. PRIM-30, characterization and prospective applications

Exopolysaccharides (EPS) are biopolymers produced by bacteria, having potential industrial applications. An EPS produced by a bacterium designated as PRIM-30 isolated from the deep seawater collected from offshore region of Cochin, India was studied. The isolate was identified as Labrenzia sp. based on 16S rRNA gene sequencing. Under optimum conditions for EPS production, the EPS yield was 840mgL(-1) culture medium. The average molecular weight of the EPS was 269kDa and composed of glucose, arabinose, galacturonic acid and mannose in the ratio 14.4:1.2:1:0.6. Importantly, the purified EPS contained 4.76% (w/w) sulfate groups. Viscosity of the (1% w/v) EPS was 3.92cP (shear rate 300s(-1), 25°C). Anodic peak potential (Epa) of the EPS by cyclic voltametric measurement was -0.7V. The EPS showed antioxidant activities with IC50 values of 640 and 190μgmL(-1), respectively, for the inhibition of DPPH and superoxide radicals. The EPS displayed a linear dose dependent increase in total antioxidant capacity and ferric reducing power activities. To date, only a very few marine alphaproteobacterial representatives have been reported for EPS production and this study for the first time, shows the production of a sulfated EPS by a member of the genus Labrenzia.

Fontibacter flavus gen. nov., sp. nov., a member of the family 'Cyclobacteriaceae', isolated from a hot spring

The taxonomic position of a bright orange-pigmented bacterial strain, designated CC-GZM-130(T), isolated from a water sample of the Guan-zing-ling hot spring, southern Taiwan, was studied. The strain was able to grow on nutrient agar at 25-40 degrees C and in the presence of 1-3 % (w/v) NaCl. Comparative analyses of the 16S rRNA gene sequence showed that the isolate was grouped in the vicinity of the genus Aquiflexum with the highest sequence similarity of 92.1 % to the type strain of Aquiflexum balticum, followed by sequence similarities of 92.0, 91.6 and 91.5 % to the type strains of Algoriphagus ornithinivorans, Algoriphagus hitonicola and Belliella baltica, respectively. The polyamine pattern showed that the major compound was sym-homospermidine. The quinone system was menaquinone MK-7. The polar lipid profile was composed predominantly of phosphatidylethanolamine, three polar lipids and one aminolipid. Minor amounts of other lipids were also detectable. The main characteristics of the fatty acid profiles of strain CC-GZM-130(T), B. baltica and Aquiflexum balticum were similar, with iso-C(15 : 0), iso-C(17 : 1)ω 9c and iso-C(17 : 0) 3-OH as the major fatty acids, but some qualitative and quantitative differences were observed. The DNA G+C content of the novel strain was 53.2 mol%. The isolate clearly differed genotypically and phenotypically from representatives of the most closely related genera. On the basis of these differences, a novel species in a new genus, Fontibacter flavus gen. nov., sp. nov., is proposed with CC-GZM-130(T) (=CCUG 57694(T)=CCM 7650(T)) as the type strain of the type species.