Homogeneous versus heterogeneous probes for microbial ecological microarrays

Microbulbifer echini sp. nov., isolated from the gastrointestinal tract of a purple sea urchin, Heliocidaris crassispina

A novel bacterium, designated as strain AM134T, was isolated from the gut of a purple sea urchin (Heliocidaris crassispina) gathered from the coastal waters of Dokdo, Korea. Strain AM134T was Gram-stain-negative, both catalase- and oxidase-positive, strictly aerobic and showed a rod-coccus cell cycle. Optimum growth occurred at 30 °C, in the presence of 2 % (w/v) NaCl and at pH 7. The 16S rRNA gene sequence analysis showed that strain AM134T belonged to the genus Microbulbifer in the family Alteromonadaceae and had high 16S rRNA gene sequence similarity (>97 %) with Microbulbifer epialgicus F-104T (98.9 % similarity) and Microbulbifer variabilis Ni-2088T (98.6 % similarity). The polar lipid profile of strain AM134T was composed of phosphatidylethanolamine, phosphatidylserine, three unidentified aminophospholipids, two unidentified phospholipids, an unidentified amino lipid and six unidentified lipids. The major respiratory quinone was identified as ubiquinone-8 (Q-8). The major cellular fatty acids were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C16 : 0. The DNA-DNA hybridization analysis showed that the strain shared less than 28 % genomic relatedness with Microbulbifer epialgicus DSM 18651T (27±3 %) and Microbulbifer variabilis ATCC 700307T (15±1 %). The G+C content of the genomic DNA was 56.1 mol%. The results of the phylogenetic, phenotypic and genotypic analyses suggest that strain AM134T represents a novel species in the genus Microbulbifer, for which the name Microbulbifer echini is proposed. The type strain is AM134T (=KACC 18258T=JCM 30400T).

Flexivirga lutea sp. nov., isolated from the faeces of a crested ibis, Nipponia nippon, and emended description of the genus Flexivirga

A novel Gram-staining-positive, aerobic, non-motile and coccus-shaped bacterium, designated strain TBS-100T, was isolated from the faeces of a crested ibis, Nipponia nippon. The phylogenetic analysis based on the 16S rRNA gene sequences showed that the closest relative of TBS-100T was Flexivirga alba DSM 24460T with 97.11 % sequence similarity, and that strain TBS-100T belonged to the genus Flexivirga. The optimum growth conditions for strain TBS-100T were 30 °C, at a pH of 7 and in the presence of 0 % (w/v) NaCl. The primary cellular fatty acids of strain TBS-100T were anteiso-C17 : 0 and iso-C17 : 0. The predominant isoprenoid quinones were MK-8 (H4) (70.2 %) and MK-8 (H6) (29.7 %). The polar lipids were diphosphatidylglycerol, phosphatidylinositol, seven unidentified lipids and an unidentified phospholipid. The whole-cell sugars of strain TBS-100T were ribose, glucose, galactose, rhamnose and mannose. The peptidoglycan contained alanine, lysine, glutamic acid, glycine and aspartic acid. The DNA G+C content was 64.8 mol%. The phenotypic, phylogenetic and genotypic analyses indicated that strain TBS-100T represents a novel species of the genus Flexivirga for which the name Flexivirga lutea sp. nov. is proposed. The type strain is TBS-100T (=KCTC 39625T=JCM 31200T). In addition, an emended description of the genus Flexivirga is proposed.

Sedimentitalea todarodis sp. nov., isolated from the intestinal tract of a Japanese flying squid

A novel Gram-stain-negative, motile, aerobic and rod-shaped alphaproteobacterium, designated strain KHS03T, was isolated from the intestinal tract of a Japanese flying squid, Todarodes pacificus, which was collected from the East Sea, Korea. The new isolate shared 97.4 % 16S rRNA gene sequence similarity with Sedimentitalea nanhaiensis NH52FT. The isolate grew optimally at 25 °C and pH 7 in the presence of 1-2 % (w/v) NaCl, and had an absolute requirement of sodium ions for growth. The major cellular fatty acid was C18 : 1ω7c. The primary isoprenoid quinone was ubiquinone-10. Polar lipids comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid and two unidentified lipids. Genotypic analyses indicated that the whole genomic DNA of the isolate had a G+C content of 59.9 mol%. DNA-DNA hybridization showed that the isolate shared 17.1±2.3 % (reciprocal 17.0±1.9 %) genomic relatedness with the closest related type strain, S. nanhaiensis NH52FT. Strain KHS03T is thus suggested to represent a novel species of the genus Sedimentitalea, for which the name Sedimentitalea todarodis sp. nov. is proposed. The type strain is KHS03T (=KCTC 42412T=JCM 31160T).

Bizionia fulviae sp. nov., isolated from the gut of an egg cockle, Fulvia mutica

A novel Gram-staining-negative, non-spore-forming, non-flagellated, non-motile, aerobic, saffron-coloured, rod-shaped bacterium that did not produce flexirubin-type pigments was designated strain EM7T and was distinct from other members of the genus Bizionia by produce carotenoid-type pigments and being able to grow independently of NaCl. Strain EM7T was isolated from the intestinal tract of an egg cockle, Fulvia mutica, which had been collected from the West Sea in Korea. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain EM7T belonged to the genus Bizionia, and showed sequence similarity to Bizionia paragorgiae KMM 6029T (97.9 %) and Bizionia saleffrena HFDT (97.73 %). Growth occurred on marine agar 2216 at 0–25 °C (optimum, 20 °C) and at pH 6–9 (optimum, pH 7). Growth occurred in the presence of 0–10 % (w/v) NaCl (optimum, 2 %, w/v, NaCl). The major cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, iso-C15 : 1 G, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C17 : 0 3-OH and iso-C16 : 0 3-OH. The major respiratory quinone was menaquinone MK-6. The polar lipids of strain EM7T comprised phosphatidylethanolamine, three unidentified aminolipids, an unidentified aminophospholipid and two unidentified lipids. The genomic DNA G+C content was 34.8 mol%. Bizionia paragorgiae KMM 6029T and Bizionia saleffrena HFDT to Bizionia paragorgiae KCTC 12304T and Bizionia saleffrena CIP 108534T, respectively. Thus, it is proposed that the isolate represents a novel species, Bizionia fulviae sp. nov., with strain EM7T ( = KACC 18255T = JCM 30417T) as the type strain.

Detecting unknown sequences with DNA microarrays: explorative probe design strategies

Designing environmental DNA microarrays that can be used to survey the extreme diversity of microorganisms existing in nature, represents a stimulating challenge in the field of molecular ecology. Indeed, recent efforts in metagenomics have produced a substantial amount of sequence information from various ecosystems, and will continue to accumulate large amounts of sequence data given the qualitative and quantitative improvements in the next-generation sequencing methods. It is now possible to take advantage of these data to develop comprehensive microarrays by using explorative probe design strategies. Such strategies anticipate genetic variations and thus are able to detect known and unknown sequences in environmental samples. In this review, we provide a detailed overview of the probe design strategies currently available to construct both phylogenetic and functional DNA microarrays, with emphasis on those permitting the selection of such explorative probes. Furthermore, exploration of complex environments requires particular attention on probe sensitivity and specificity criteria. Finally, these innovative probe design approaches require exploiting newly available high-density microarray formats.

Comparing microarrays and next-generation sequencing technologies for microbial ecology research

Recent advances in molecular biology have resulted in the application of DNA microarrays and next-generation sequencing (NGS) technologies to the field of microbial ecology. This review aims to examine the strengths and weaknesses of each of the methodologies, including depth and ease of analysis, throughput and cost-effectiveness. It also intends to highlight the optimal application of each of the individual technologies toward the study of a particular environment and identify potential synergies between the two main technologies, whereby both sample number and coverage can be maximized. We suggest that the efficient use of microarray and NGS technologies will allow researchers to advance the field of microbial ecology, and importantly, improve our understanding of the role of microorganisms in their various environments.

Advances in molecular and "-omics" technologies to gauge microbial communities and bioremediation at xenobiotic/anthropogen contaminated sites

Microbial bioremediation has been well-demonstrated as an ecofriendly and cost-competitive strategy for elimination of xenobiotic and or anthropogenic compounds from the polluted environments. However, successful execution of these versatile bioremediation strategies requires a thorough understanding of factors governing the growth, metabolism, dynamics and functions of indigenous microbial communities at contaminated sites. Recent innovative breakthroughs in genotypic profiling, ultrafast genome pyrosequencing, metagenomics, metatranscriptomics, metaproteomics and metabolomics along with bioinformatics tools have provided crucial in-sights of microbial communities and their mechanisms in bioremediation of environmental pollutants. Moreover, advances in these technologies have significantly improved the process of efficacy determination and implementation of microbial bioremediation strategies. The current review is focused on application of these molecular and "-omics" technologies in gauging the innate microbial community structures, dynamics and functions at contaminated sites or pollution containment facilities.

DNA chip analysis in diverse organisms with unsequenced genomes

Whether for basic research or biotechnology, DNA microarrays have become indispensable tools for studying the transcriptome. Normally, analyses begin with a set of known cDNA sequences to prepare microarray chips specific for a target organism with an extensively sequenced and annotated genome. For many organisms, however, genome programs are not complete or have not been initiated. The present study demonstrates that, whether using homologous or heterologous arrays, the chances of seeing interesting differences are similar. When a specific DNA microarray is not available, the results indicate that a reverse approach based on a heterologous array can be used to probe for interesting differences in gene expression. This may be sufficient in many studies but, if necessary, the genes exhibiting the most significant changes subsequently could be identified by traditional molecular approaches. Such a reverse strategy can provide a convenient and inexpensive approach to probe for significant genetic changes in many diverse studies, to monitor or mine critical biological information for basic or applied research, long before complete sequence data are available.

Development of microbial genome-probing microarrays using digital multiple displacement amplification of uncultivated microbial single cells

A crucial problem in the use of previously developed genome-probing microarrays (GPM) has been the inability to use uncultivated bacterial genomes to take advantage of the high sensitivity and specificity of GPM in microbial detection and monitoring. We show here a method, digital multiple displacement amplification (MDA), to amplify and analyze various genomes obtained from single uncultivated bacterial cells. We used 15 genomes from key microbes involved in dichloromethane (DCM)-dechlorinating enrichment as microarray probes to uncover the bacterial population dynamics of samples without PCR amplification. Genomic DNA amplified from single cells originating from uncultured bacteria with 80.3-99.4% similarity to 16S rRNA genes of cultivated bacteria. The digital MDA-GPM method successfully monitored the dynamics of DCM-dechlorinating communities from different phases of enrichment status. Without a priori knowledge of microbial diversity, the digital MDA-GPM method could be designed to monitor most microbial populations in a given environmental sample.