Lutimonas zeaxanthinifaciens sp. nov., a zeaxanthin-producing marine bacterium isolated from coastal sediment

A Gram-stain-negative, yellow-pigmented, strictly aerobic, non-flagellated, motile by gliding, rod-shaped bacterium, designated strain YSD2104T, was isolated from a coastal sediment sample collected from the southeastern part of the Yellow Sea. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain YSD2104T was closely related to three type strains, Lutimonas vermicola IMCC1616T (97.4 %), Lutimonas saemankumensis SMK-142T (96.9 %), and Lutimonas halocynthiae RSS3-C1T (96.8 %). Strain YSD2104T has a single circular chromosome of 3.54 Mbp with a DNA G+C content of 38.3 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain YSD2104T and the three type strains (L. vermicola IMCC1616 T, L. saemankumensis SMK-142T, and L. halocynthiae RSS3-C1T) were 74.0, 86.2 and 73.6 %, and 17.9, 30.3 and 17.8 %, respectively. Growth was observed at 20-30 °C (optimum, 30 °C), at pH 6.5-8.5 (optimum, pH 7.0), and with NaCl concentrations of 1.5-3.5 % (optimum, 2.5 %). The major carotenoid was zeaxanthin, and flexirubin-type pigment was not produced. The major respiratory quinone was menaquinone-6. The major fatty acids (>10 %) were iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, summed feature 3 (C16 : 1  ω6c and/or C16 : 1  ω7c), and summed feature 9 (iso-C17 : 1  ω9c and/or 10-methyl C16 : 0). The major polar lipids were phosphatidylethanolamine, one unidentified aminophospholipid, two unidentified aminolipids, and eight unidentified lipids. Conclusively, based on this polyphasic approach, we classified strain YSD2104T (=KCTC 102008T=JCM 36287T) as representing a novel species of the genus Lutimonas and proposed the name Lutimonas zeaxanthinifaciens sp. nov.

Effects of Hermetia illucens larvae meal on the Pacific white shrimp (Litopenaeus vannamei) revealed by innate immunity and 16S rRNA gene sequencing analysis

The larvae of the black soldier fly, Hermetia illucens, are now attracting attention and becoming promising sources for aquafeed ingredient due to the nutritious substance. However, the introduction of a novel ingredient into the recipe may have unpredictable effects on the innate immune function and gut bacteria composition of crustaceans. Therefore, the present study aimed to evaluate how dietary black soldier fly larvae meal (BSFLM) affected the antioxidant ability, innate immunity and gut microbiome of shrimp (Litopenaeus vannamei) fed with a practical diet, including the gene expression of Toll and immunodeficiency (IMD) pathways. Six experimental diets were formulated by replacing gradient levels of fish meal (0 %, 10 %, 20 %, 30 %, 40 % and 50 %) based on a commercial shrimp diet. Four replicates of shrimp were fed different diets three times daily for 60 days. Growth performance linearly decreased with increasing BSFLM inclusion. Results of antioxidative enzyme activities and gene expression suggested that low dietary BSFLM levels activated the antioxidant capacity of shrimp, while dietary BSFLM levels up to 100 g/kg may induce oxidative stress and inhibit glutathione peroxidase activity. Although traf6, toll1, dorsal and relish were significantly upregulated in different BSFLM groups, the expression of tak1 was significantly downregulated in groups containing BSFLM, implying the immune susceptibility may be weakened. Gut flora analysis indicated dietary BSFLM altered both beneficial and opportunistic pathogenic bacterial abundance, with low levels of dietary BSFLM increased the abundance of bacteria that may contribute to carbohydrate utilization, while high levels of dietary BSFLM may cause intestinal disease and low intestinal immune response. To conclude, 60-80 g/kg of dietary BSFLM showed no adverse effects on the growth, antioxidant capacity and gut flora of shrimp, which was the adequate level in shrimp diet. While 100 g/kg dietary BSFLM may induce oxidative stress and potentially weaken the innate immunity of shrimp.

Tabrizicola rongguiensis sp. nov., isolated from the sediment of a river in Ronggui, Foshan city, China

A novel Gram-negative, aerobic, non-spore-forming, non-motile and rod-shaped bacterium, designated J26^T, was isolated from the sediment of a river in Ronggui, Foshan city, China. Strain J26^T grew optimally at 0 % (w/v) NaCl, pH 6.5-7.5, and 30 °C, and it formed milky white irregular colonies on Reasoner's 2A agar medium. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain J26^T had the highest similarity to Tabrizicola aquatica RCRI19^T (97.1 %) and formed a distinct clade in the genus Tabrizicola. Cellular components of J26^T supported this strain as a member of the genus Tabrizicola. The predominant fatty acids were C_18 : 1  ω7c, C_18 : 1  ω7c-11 methyl and C_16 : 0. Polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphorylethanolamine. Ubiquinone Q-10 was the major respiratory quinone, and the DNA G+C content was 64.2 mol%. However, low 16S rRNA gene sequence similarity and average nucleotide identity (73.56 % for ANIb between strain J26^T with RCRI19^T) demonstrated that strain J26^T should be assigned to a novel species. Moreover, the differences between J26^T and RCRI19^T in terms of physiological and biochemical properties, such as carbon, nitrogen and sulphur metabolism, further supported that J26^T represents a novel species, for which the name Tabrizicola rongguiensis sp. nov. is proposed. The type strain is J26^T (=GDMCC 1.2843^T=KCTC 92112^T).

An invasive herbivorous fish (Siganus rivulatus) influences both benthic and planktonic microbes through defecation and nutrient excretion

Direct and indirect impacts by invasive animals on plants and other animals through predation and competition have been evidenced in many ecosystems. For instance, the rabbitfish Siganus rivulatus, originating from the Red Sea, is now the most abundant species in costal habitats of South-Eastern Mediterranean Sea where it overgrazes algae. However, little is known about its impacts on microbes through release of metabolic wastes and feces. We used a mesocosm experiment to test the effect of S. rivulatus on planktonic and benthic microbial communities. Excretion of dissolved nutrients by fish resulted in higher concentrations of dissolved inorganic nitrogen (NH₄, NO₂/NO₃). This increase in availability of N was associated with higher N content in macroalgae, higher biomass of phytoplankton, higher abundance of bacterioplankton and shift in the structure of planktonic bacterial communities. The feces released mostly under the shelters where the fish rest at night, led to significant increases in diversity of sediment bacterial communities and shifts in their structure. The impact of S. rivulatus on planktonic microbes was related to the indirect bottom-up effect induced by excreted dissolved nutrients while its effect on benthic microbes was due to the direct release of both organic matter and microbes present in feces. Overall, this first evidence of the impacts of invasive species on planktonic and benthic microbes highlights that ongoing changes in fish biodiversity could have ecosystem-wide consequences.

Tabrizicola piscis sp. nov., isolated from the intestinal tract of a Korean indigenous freshwater fish, Acheilognathus koreensis

A novel Gram-negative, obligately aerobic, rod-shaped and non-motile bacterium, designated strain K13M18T, was isolated from the intestinal tract of a Korean indigenous fish, oily bitterling (Acheilognathus koreensis). Strain K13M18T formed creamy-pink colonies on a marine agar plate. Results of phylogenetic analysis based on the 16S rRNA gene sequence similarity indicated that strain K13M18T was most closely related to Tabrizicola sediminis DRYC-M-16T, sharing 97.62 % similarity with that strain. Strain K13M18T belonged to the genus Tabrizicola , which formed a cluster with Tabrizicola aquatica RCRI19T, Tabrizicola fusiformis SY72T, Tabrizicola sediminis DRYC-M-16T and Tabrizicola alkalilacus DJCT in a phylogenetic tree based on the 16S rRNA gene sequences. Strain K13M18T grown optimally in 0 % (w/v) NaCl, at pH 7 and 30 °C, in a marine broth medium. The predominant cellular fatty acids were C18 : 1 ω7c and C18 : 1 ω6c. The major respiratory isoprenoid quinone was ubiquinone Q-10. Polar lipids of strain K13M18T contained phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol, six unidentified aminophospholipids, one unidentified aminolipid and an unidentified lipid. Based on genome sequencing, the DNA G+C content of strain K13M18T was 64.08 mol %, with an average nucleotide identity value, calculated by a comparative genomic analysis of strains K13M18T and T. sediminis DRYC-M-16T, of 74.82 %. Based on the phylogenetic, genotypic, and phenotypic information, strain K13M18T is proposed to be a novel species of the genus Tabrizicola . The type strain is K13M18T (=KCTC 62659T=JCM 33230T).

Community characteristics and ecological roles of bacterial biofilms associated with various algal settlements on coastal reefs

Bacterial biofilms, which are a group of bacteria attaching to and ultimately forming communities on reefs, perform essential ecological functions in coastal ecosystems. Particularly, they may attract or repulse the settling down of opportunistic algae. However, this phenomenon and the interaction mechanism are not fully understood. This study investigated reefs from the Changdao coastal zone to determine the structures and functions of bacterial biofilms symbiosing with various algae using high-throughput sequencing analysis. The Shannon diversity index of microbiota with algal symbiosis reached 5.34, which was higher than that of microbiota wherein algae were absent (4.80). The beta diversity results for 11 samples revealed that there existed a separation between bacterial communities on reefs with and without attached algae, while communities with similar algae clustered together. The taxa mostly associated with algae-symbiotic microbiota are the Actinobacteria phylum, and the Flavobacteriia and Gammaproteobacteria classes. The Cyanobacteria phylum was not associated with algae-symbiotic microbiota. As revealed by functional analysis, the bacteria mostly involved in the metabolism of sulfur were represented by brown and red algae in the biofilm symbiosis. Bacteria related to the metabolism of certain trace elements were observed only in specific groups. Moreover, phototrophy-related bacteria were less abundant in samples coexisting with algae. This study established the link between bacterial biofilms and algal settlements on costal reefs, and revealed the possible holobiont relationship between them. This may provide new technical directions toward realizing algal cultivation and management during the construction of artificial reef ecosystems.

Flammeovirga pectinis sp. nov., isolated from the gut of the Korean scallop, Patinopecten yessoensis

A novel Gram-stain-negative, aerobic, rod-shaped, reddish-orange-coloured, gliding bacterial strain, designated L12M1^T, was isolated from the gut of the Korean scallop, Patinopecten yessoensis. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain L12M1^T formed a monophyletic clade with the strains in the genus Flammeovirga and showed highest 16S rRNA gene sequence similarity to Flammeovirga kamogawensis YS10^T (98.66 %). The major cellular fatty acids of strain L12M1^T were iso-C_15 : 0 and C_20 : 4ω6,9,12,15c. The predominant isoprenoid quinone was MK-7. The major polyamines were spermidine, cadaverine and the minor polyamine was putrescine. The DNA G+C content was 32.1 mol%. The phylogenetic, phenotypic, biochemical, chemotaxonomic and genotypic results indicated that strain L12M1^T represents a novel species of the genus Flammeovirga, for which the name Flammeovirga pectinis sp. nov. is proposed. The type strain is L12M1^T (=KCTC 62750^T=JCM 33169^T).

The deposit feeder Capitella teleta has a unique and relatively complex microbiome likely supporting its ability to degrade pollutants

Capitella teleta is a sediment-dwelling marine polychaete that is often found in high densities in association with organic matter and pollutants. While C. teleta has been reported to transform a variety of aromatic hydrocarbons, the mechanisms by which degradation occurs are unknown. Moreover, there is continuing debate on the role of host and microbiota in degradation activity. The aims of this study were to characterize the gut microbiome of C. teleta and to identify microbiota that could potentially play a role in degradation of organic matter and aromatic hydrocarbons. Sequencing analysis of the 16S rRNA genes from the intestinal tracts of adult worms revealed a unique microbiome that was distinct from that of the worm's sediment food source and fecal pellets. About 66% of the 775 identified OTUs from the C. teleta gut microbiome were found to be unique to the worm and displayed high inter-individual variability. The gut microbiome was dominated by members of the genera Arcobacter, Pseudoalteromonas, Methylobacterium, and Propionibacterium. Functional analyses of microbiota revealed that hydrocarbon treatment led to a proliferation of gene classes involved in chemoheterotrophy and aromatic compound degradation. Of the 18 most abundant taxa identified, 50% were members of genera containing hydrocarbon (PAH)-degrading members, including Acinetobacter, Thalassotalea, and Achromobacter. Data obtained in this study will be useful to understand the biology of this marine polychaete and to elucidate the role that gut bacteria play in worm catabolism and the transformation of sediment organic pollutants.

Vagococcus martis sp. nov., isolated from the small intestine of a marten, Martes flavigula

A novel coccus-shaped, Gram-stain-positive, non-motile and facultative aerobic bacterium, designated strain D7T301T, was isolated from the small intestine of a marten, Martes flavigula, which was killed on the road in Pocheon-si, Gyeonggi-do, Republic of Korea. Grown on a tryptic soy yeast agar plate, colonies had a creamy colour and irregular form. The new isolate formed a monophyletic clade with Vagococcus penaei CD276T on a phylogenetic consensus tree based on the 16S rRNA gene sequence. The isolate grew optimally at 37 °C and pH 7 in the presence of 0.5 % (w/v) NaCl. The isolate was catalase- and oxidase-negative. The cell-wall peptidoglycan was type A4α l-Lys-d-Asp. The major cellular fatty acids were C16 : 0, C14 : 0, and C16 : 1ω9c. The predominant respiratory quinone was menaquinone MK-7 (85.1 %). The DNA G+C content based on genome sequencing was 33.8 mol%. The average nucleotide identity value obtained from comparative genomic analysis between strain D7T301T and V. penaei CIP 109914T was 72.6 %. On the basis of the phenotypic, phylogenetic, biochemical, chemotaxonomic, and genotypic analyses, Vagococcusmartis is proposed as a novel species of the genus Vagococcus. The type strain is D7T301T (=KCTC 21069T=JCM 31178T).

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.

Proteus cibarius sp. nov., a swarming bacterium from Jeotgal, a traditional Korean fermented seafood, and emended description of the genus Proteus

A novel Proteus-like, Gram-stain-negative, facultatively anaerobic, rod-shaped bacterium, designated strain JS9T, was isolated from Korean fermented seafood, Jeotgal. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain JS9T belonged to the genus Proteus in the family Enterobacteriaceae. The highest 16S rRNA gene sequence similarity of strain JS9T was to Proteus vulgaris KCTC 2579T (98.98 %) and the genomic DNA G+C content is 39.0 mol%. DNA-DNA hybridization values were measured and strain JS9T showed <20.8 % genomic relatedness with closely-related members of the genus Proteus. The isolate showed bacterial motility and swarming activity similar to those of pathogenic Proteus mirabilis but distinct from those of other species of the genus Proteus. The isolate grows optimally at 30 °C, at pH 7, and in the presence of 2 % (w/v) NaCl. The main respiratory quinones are ubiquinone Q-8 and Q-10, and the major cellular fatty acids are C16 : 0, summed feature 3 and summed feature 8. The polar lipids comprise phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unidentified amino lipid, two unidentified amino-phospholipids, and three unidentified lipids. Based on phylogenetic, phenotypic, chemotaxonomic and genotypic analyses, strain JS9T represents a novel species of the genus Proteus, for which the name Proteus cibarius sp. nov. is proposed. The type strain is JS9T (=KACC 18404T=JCM 30699T). An emended description of the genus Proteus is also provided.

Simplicispira piscis sp. nov., isolated from the gut of a Korean rockfish, Sebastes schlegelii

A novel Gram-stain-negative, aerobic, motile and rod-shaped bacterium, designated strain RSG39T, was isolated from the gut of a Korean rockfish, Sebastes schlegelii. The 16S rRNA gene sequence analysis revealed that strain RSG39T belonged to the genus Simplicispira in the class Betaproteobacteria and its highest sequence similarity was shared with S. psychrophila (98.4 %). The isolate grew optimally at 20 °C, at pH 7 and with 0 % (w/v) NaCl. The main respiratory quinone of the isolate was ubiquinone Q-8. The major cellular fatty acids were C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The polar lipids of the isolate were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol and six unidentified lipids. The DNA–DNA hybridization values showed < 7.4 % genomic relatedness with closely related strains. The genomic DNA G+C content was 65.2 mol %. Based on phylogenetic, phenotypic, chemotaxonomic and genotypic analyses, strain RSG39T represents a novel species of the genus Simplicispira, for which the name Simplocospira piscis sp. nov. is proposed. The type strain is RSG39T ( = KACC 17539T = JCM 19291T).

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.