In-Suk Park

Identification and characterization of a bacteriocin produced by an isolated Bacillus sp. SW1-1 that exhibits antibacterial activity against fish pathogens

The selected isolate, Bacillus sp. SW1-1 showed antibacterial activity against both Gram-positive and Gram-negative bacteria involved in fish diseases, including Edwardsiella tarda, Streptococcus iniae, S. parauberis, Vibrio anguillarum, and V. harveyi. The Maximum bacteriocin production was observed at 30°C after 24 h with brain heart infusion medium (pH 7.0). The bacteriocin SW1-1 was purified by 50% ammonium sulfate precipitation, followed by HiPrep diethylaminoethyl 16/10 FF and Sephacryl S-100 High resolution column chromatography. The substance was characterized as a bacteriocin-like inhibitory substance with a molecular mass of 38 kDa. Bacteriocin SW1-1 was sensitive to the proteolytic action of pepsin, trypsin, chymotrypsin, and protease types I and XIV, and relatively heat labile, despite the fact that bacteriocin activity was still detected after heating at 100°C for 30 min. The activity of bacteriocin SW1-1 was stable in the pH range of 2.0–11.0, and relatively unaffected by organic chemicals. The bacteriocin SW1-1 had a bacteriolytic mechanism, resulting in cell wall degradation of E. tarda. These characteristics indicate that this bacteriocin may be a potential candidate for alternative agent to control important pathogens of fish diseases in aquaculture.

Molecular and functional characterizations of a Kunitz-type serine protease inhibitor FcKuSPI of the shrimp Fenneropenaeus chinensis

Serine proteinase inhibitors play important and diverse roles in biological processes such as coagulation, defense mechanisms, and immune responses. Here, we identified and characterized a Kunitz-type proteinase inhibitor, designated FcKuSPI, of the BPTI/Kunitz family of serine proteinase inhibitors from the hemocyte cDNA library of the shrimp Fenneropenaeus chinensis. The deduced amino acid sequence of FcKuSPI comprises 80 residues with a putative signal peptide of 15 amino acids. The predicted molecular weight of the mature peptide is 7.66 kDa and its predicted isoelectric point is 8.84. FcKuSPI includes a Kunitz domain containing six conserved cysteine residues that are predicted to form three disulfide bonds. FcKuSPI shares 44-53% homology with BPTI/Kunitz family members from other species. FcKuSPI mRNA was expressed highly in the hemocytes and moderately in muscle in healthy shrimp. Recombinant FcKuSPI protein demonstrated anti-protease activity against trypsin and anticoagulant activity against citrated human plasma in a dose-dependent manner in in vitro assays.

Polaribacter haliotis sp. nov., isolated from the gut of abalone Haliotis discus hannai

A Gram-stain-negative, aerobic, non-motile and coccoid, ovoid or rod-shaped bacterial strain, designated RA4-7T, was isolated from the gut of an abalone (Haliotis discus hannai) collected from the sea around Jeju island, South Korea, and subjected to a polyphasic taxonomic study. RA4-7T grew optimally at 25 °C, at pH 7.0-7.5 and in the presence of 2.0-3.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that RA4-7T represented a member of the genus Polaribacter. RA4-7T exhibited 16S rRNA gene sequence similarity values of 97.64 and 97.23 % to Polaribacter atrinae WP25T and Polaribacter dokdonensis DSW-5T, respectively, and of 93.83-96.99 % to the type strains of the other species of the genus Polaribacter. RA4-7T contained MK-6 as the predominant menaquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 3-OH and iso-C15 : 0as the major fatty acids. The major polar lipids detected in RA4-7T were phosphatidylethanolamine and one unidentified lipid. The DNA G+C content of RA4-7T was 30.5 mol% and its DNA-DNA relatedness values with the type strains of P. atrinae and P. dokdonensis were 16 and 11 %, respectively. Differential phenotypic properties, in combination with its phylogenetic and genetic distinctiveness, revealed that RA4-7T is separated from species of the genus Polaribacter with validly published names. On the basis of the data presented, RA4-7T represented a novel species of the genus Polaribacter, for which the name Polaribacterhaliotis sp. nov. is proposed. The type strain is RA4-7T (=KCTC 52418T=NBRC 112383T).

Colwellia mytili sp. nov., isolated from mussel Mytilus edulis

A Gram-stain-negative, aerobic, motile and rod-shaped bacterial strain, designated RA2-7T, was isolated from a mussel (Mytilus edulis) collected from the South Sea, South Korea, and subjected to a taxonomic study using a polyphasic approach. Strain RA2-7T grew optimally at 20 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain RA2-7T belonged to the genus Colwellia. Strain RA2-7T exhibited 16S rRNA gene sequence similarity values of 98.3, 98.0 and 97.5 % to the type strains of Colwellia sediminilitoris, Colwellia aestuarii and Colwellia polaris, respectively, and of 94.5-96.5 % to the type strains of the other species of the genus Colwellia. Strain RA2-7T contained Q-8 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0 as the major fatty acids. The major polar lipids detected in strain RA2-7T were phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain RA2-7T was 39.0±0.04 mol% and its DNA-DNA relatedness values with the type strains of C. sediminilitoris, C. aestuarii and C. polaris were 14-19 %. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain RA2-7T is separated from recognized species of the genus Colwellia. On the basis of the data presented, strain RA2-7T is considered to represent a novel species of the genus Colwellia, for which the name Colwellia mytili sp. nov. is proposed. The type strain is RA2-7T (=KCTC 52417T=NBRC 112381T).

Tenacibaculum ascidiaceicola sp. nov., isolated from the golden sea squirt Halocynthia aurantium.

A Gram-stain-negative, non-flagellated, non-spore-forming bacterial strain motile by gliding, designated RSS1-6T, was isolated from a golden sea squirt Halocynthia aurantium and its taxonomic position was investigated by using a polyphasic approach. Strain RSS1-6T grew optimally at 30-37 °C and in the presence of 1.0-4.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences showed that strain RSS1-6T fell within the clade comprising species of the genus Tenacibaculum, clustering with the type strains of Tenacibaculum discolor, Tenacibaculum litoreum and Tenacibaculum gallaicum with which it exhibited 16S rRNA gene sequence similarity values of 98.5-99.5 %. Strain RSS1-6T contained MK-6 as the predominant menaquinone and iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) as the major fatty acids. The major polar lipids of strain RSS1-6T were phosphatidylethanolamine, two unidentified lipids, one unidentified aminophospholipid and one unidentified glycolipid. The DNA G+C content was 32.5 mol% and the mean DNA-DNA relatedness values with the type strains of T. discolor, T. litoreum and T. gallaicum were 17.3-25.2 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain RSS1-6T is separated from other recognized species of the genus Tenacibaculum. On the basis of the data presented, strain RSS1-6T is considered to represent a novel species of the genus Tenacibaculum, for which the name Tenacibaculum ascidiaceicola sp. nov. is proposed. The type strain is RSS1-6T ( = KCTC 42702T = NBRC 111225T).

Shewanella sp. Ke75 esterase with specificity for p-nitorphenyl butyrate: Gene cloning and characterization

A bacterial strain that produces a cold-adapted esterase was isolated from tidal flats and identified as Shewanella sp. Ke75. In the present study, the corresponding gene was cloned using the shotgun method. The amino acid sequence deduced from the nucleotide sequence (957 bp) corresponded to a protein of 318 amino acid residues with a calculated molecular weight of 34875 Da. The esterase showed 68 and 57% identities with the putative esterases of Shewanella amazonensis SB2B and Colwellia psychrerythraea 34H, respectively. The esterase contained a putative leader sequence, as well as the conserved catalytic triad (Ser, His, Asp), consensus pentapeptide GXSXG, and oxyanion hole sequence (HG). The protein Ke75 was produced in both soluble and insoluble forms when Escherichia coli cells harboring the gene were cultured at 30°C. The enzyme showed specificity for C4 (butyrate) as a substrate, with little activity toward the other p-nitrophenyl esters tested. The optimum pH and temperature for enzyme activity were pH 9.0 and 30°C, respectively. Relative activity remained up to 60% even at 5°C with an activation energy of 6.29 kcal/mol, which indicated that it was a cold-adapted enzyme. Enzyme activity was enhanced in the presence of Mn2+ ions, but inhibited by Cd2+, Cu2+, Hg2+, and Zn2+ ions.

Octadecabacter ascidiaceicola sp. nov., isolated from a sea squirt (Halocynthia roretzi).

A Gram-stain-negative, non-spore-forming, non-flagellated and coccoid, ovoid or rod-shaped bacterial strain, RA1-3T, was isolated from a sea squirt (Halocynthia roretzi) collected from the South Sea, South Korea, and subjected to a taxonomic study using a polyphasic approach. Strain RA1-3T grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0 % (w/v) NaCl. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences revealed that strain RA1-3T clustered with the type strains of three species of the genus Octadecabacter, showing 97.54-98.41 % 16S rRNA gene sequence similarity. Sequence similarities to other recognized species were less than 96.97 %. Strain RA1-3T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The major polar lipids of strain RA1-3T were phosphatidylcholine, phosphatidylglycerol, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain RA1-3T was 56 mol% and DNA-DNA relatedness values with the type strains of Octadecabacter temperatus, Octadecabacter antarcticus and Octadecabacter arcticus were 13-24 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain RA1-3T is separated from other recognized species of the genus Octadecabacter. On the basis of the data presented, strain RA1-3T is considered to represent a novel species of the genus Octadecabacter, for which the name Octadecabacter ascidiaceicola sp. nov. is proposed. The type strain is RA1-3T ( = KCTC 42605T = CECT 8868T).

Antibacterial Activity of Bacteria Isolated from Rocks on the Seashore

There is a great deal of research interest regarding substitutes for antibiotics because of various obstacles to the efficacy and use of antibiotics. We isolated and analyzed diversity of microbiota which exhibited antibacterial activity against 23 pathogenic bacteria, to develop alternative agent of antibiotics. By investigating the microbiota from rocks on the seashore, we characterized and obtained various antibacterial material-producing bacteria. Thirty-one isolates belong to four genera and seven species, according to 16S rDNA sequence analysis, showed antibacterial activities against 23 pathogenic bacteria. The Identity of 16S rDNA sequences indicated three species of Bacillus, one species of Paenibacillus, one species of Pseudomonas and two species of Enterobacter. Two isolates were similar to Bacillus aerophilus, four isolates were similar to Bacillus pumilus, seven isolates were similar to Bacillus safensis, 15 isolates were similar to Paenibacillus polymyxa, respectively. In addition, one isolate was similar with Pseudomonas poae, one isolate was similar to Enterobacter asburiae, and one isolate was similar to Enterobacter ludwigii, respectively. Variations of antibacterial activity and level among the same species were indicated the diverse strains of isolates. Vibrio vulnificus showed the highest degree of growth inhibition by 29 isolates. Further studies regarding antibacterial materials and bacteria suggest that development of probiotic strains or alternative agents to antibiotics.

Corrigendum: Bizionia berychis sp. nov., isolated from intestinal tract of a splendid alfonsino (Beryx splendens)

Author affiliations: Biotechnology Research Division, National Institute of Fisheries Science (NIFS), Gijang, Busan 46083, Republic of Korea; Department of Food Science and Biotechnology, Sungkyunkwan University, Jangan-gu, Suwon 16419, Republic of Korea; Distant-water Fisheries Resources Division, National Institute of Fisheries Science (NIFS), Gijang, Busan 46083, Republic of Korea; Department of Biology, Kyung Hee University, Seoul 02447, Republic of Korea. *Correspondence: Jung-Hoon Yoon, jhyoon69@skku.edu

Corrigendum: Paracoccus alimentarius sp. nov., isolated from a Korean foodstuff, salted pollack

Author affiliations: Biotechnology Research Division, National Institute of Fisheries Science (NIFS), Gijang, Busan 46083, Republic of Korea; Department of Food Science and Biotechnology, Sungkyunkwan University, Jangan-gu, Suwon 16419, Republic of Korea. *Correspondence: Jung-Hoon Yoon, jhyoon69@skku.edu CORRIGENDUM Kim et al., Int J Syst Evol Microbiol 2018;68:2113–2113 DOI 10.1099/ijsem.0.002789