• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.531-536
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• 2009

A urease-positive bacterium isolated from sea water was identified as Photobacterium sp. by morphological, biochemical, and 16s rRNA gene analyses and named Photobacterium sp. strain HA-2. 2.0-fold increase enzyme activity was observed in LB medium containing 3% NaCl and 0.1% urea or not and the enzyme activity was 16.0-fold lower compared to urease-positive Vibrio parahaemolyticus AQ4673 strain when grown in the LB medium containing 3% NaCl with 0.1% urea. The cloning and sequencing of Photobacterium sp. strain HA-2 urease gene cluster is currently being analyzed in our laboratory.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.639-643
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• 2015

In this study, we cloned and sequenced the 15,204-bp DNA region containing the gene cluster for urease production from the chromosome of the environmental Photobacterium sp. strain HA-2. We identified 15 open reading frames (ORFs) and the G+C content was 40.3%. The urease gene cluster of Photobacterium sp. strain HA-2 consisted of seven genes, namely, ureDABCEF and ureG. There were five ORFs of urease genes in the opposite direction, which were homologous to the nickel transport operons (nik) of Vibrio parahaemolyticus and Escherichia coli. The genetic organization and sequences of the urease genes of Photobacterium sp. strain HA-2 resembled those found in Vibrio fischeri and V. parahaemolyticus.

• Journal of fish pathology
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• v.36 no.2
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• pp.251-261
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• 2023

Photobacterium sp. YW2207 was isolated from rainbow trout raised in a fish farm located in Yeongwol-gun, Gangwon Province, South Korea. Based on 16S rRNA sequence analysis and phylogenetic analysis, it was confirmed that Photobacterium sp. YW2207 showed 100% similarity with Photobacterium piscicola and Photobacterium phosphoreum, and 94.6% similarity with P. damselae subsp. damselae. Biochemical analysis revealed that Photobacterium sp. YW2207 is a Gram-negative, motile bacterium with a cell size of 1.5~3×3~5 ㎛. The bacteria were cultured on nutrient agar, brain heart infusion agar, Muller-Hinton agar, tryptic soy agar, and thiosulfate citrate bile sucrose agar with NaCl concentrations ranging from 0 to 2.5%. The API50CHE and API20E tests indicated lower utilization capabilities compared to the P. damselae strains provided in the API database. Furthermore, unlike most Photobacterium species, Photobacterium sp. YW2207 presented negative for catalase test. Results from the flow cytometric measurement indicated that Photobacterium sp. YW2207 exhibited a more diverse distribution of cell sizes and had larger cell sizes compared with P. damselae subsp. damselae. Minimum inhibitory concentration tests showed that Photobacterium sp. YW2207 had low susceptibility to β-Lactam and aminoglycoside antibiotics, while having high susceptibility to tetracycline, doxycycline, and quinolone antibiotics. Pathogenicity on rainbow trout revealed that an immersion of 1×10⁵ CFU/ml did not cause mortality or clinical symptoms.

• Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.311-318
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• 2013

The gene encoding an esterase from Photobacterium sp. MA1-3 was cloned in Escherichia coli using the shotgun method. The amino acid sequence deduced from the nucleotide sequence (948 bp) corresponded to a protein of 315 amino acid residues with a molecular weight of 35 kDa and a pI of 6.06. The deduced protein showed 74% and 68% amino acid sequence identities with the putative esterases from Photobacterium profundum SS9 and Photobacterium damselae, respectively. Absence of a signal peptide indicated that it was a cell-bound protein. Sequence analysis showed that the protein contained the signature G-X-S-X-G included in most serine-esterases and lipases. The MA1-3 esterase was produced in both soluble and insoluble forms when E. coli cells harboring the gene were cultured at $18^{\circ}C$. The enzyme was a serine-esterase and was active against $C_2$, $C_4$, $C_8$ and $C_{10}$ p-nitrophenyl esters. The optimum pH and temperature for enzyme activity were pH 8.0 and $30^{\circ}C$, respectively. Relative activity remained up to 45% even at $5^{\circ}C$ with an activation energy of 7.69 kcal/mol, which indicated that it was a cold-adapted enzyme. Enzyme activity was inhibited by $Cd^{2+}$, $Cu^{2+}$, $Zn^{2+}$, and $Hg^{2+}$ ions.

• Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.52-63
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• 2000

Non-specific reaction has been a problem in doing, especially, research and diagnosis for infectious agents. Avidin-biotin-peroxidase complex (ABC) techniques has widely been used to amplify a reaction. Photobacterium damse1a subsp. piscicdia (formerly Pasteurella piscicida) exhibited a capacity to bind with streptavidin non-specifically. The band, estimated 26 K Da in Western blotted paper, was blocked with biotin but incompletely. In an attempt to explore an involvement of the non-specific substance in attaching piscine cells, cell attachment test performed using anti- Ph. d. subsp piscicida sera raised mouse and rabbit exhibited slightly blocking effects for Mediterranean (1736) and significantly for Japanese (Sp 92144) isolate. Biotin decreased the attachment ability significantly for Sp92144 but it was not effective to 1736. Both isolates showed greatly enhanced attachment ability with poly-L-lysin. The non-specific binding substance was contained in bacterial extracellular products (ECPs). The substance was able to purified with 2-imminobiotin affinity column, the purified substance appeared to have 4 bands in silver staining, and had a carbohydrate branch. This purified substance showed cytotoxic effects selectively between 5 piscine cell lines. Moreover, it stimulated rainbow trout macrophage in terms of reduction of cytochrome cas well as yeast phagocytosis, significantly.

• Journal of Veterinary Clinics
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• v.19 no.1
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• pp.19-22
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• 2002

The examination with 96 bacteria isolates for antibiotics susceptibility was resulted in exploring many antibiotics resistance isolates from the diseased fishes. Vibrio sp. isolates were demonstrated over 90% resistances for Penicillin (P), Amoxicillin (Amc), Erythromycin (I), Colistin (CL). Streptomycin (S). Novobiocin (NV) and Neomycin(N), these isolates were, however, appeared over 80% susceptibilities for Norfloxacin (Nor), CE and UB. In Edwardsiella tarda case, 90 to 100% high resistance was observed for P, Doxycycline (Do), Tetracyclin (Te), Oxytetracycline (T), E, CL, Sulfamethoxasoletrimetoprim (SXT), S, Oxolinic acid (OA), W, Neomycin(N), on the contrary, 90 to 100% high susceptibilities was found for Amc, Nor, Ciprofloxacin (Cip), Orbifloxacin (ORB), Enrofloxacin (ENR), Flumeguine (UB) and NA. CL, Pefloxacin (PEF),S, Flumeguine (UB), OA, NA, NV N was exhibited 90 to 100% resistances for Streptococcus sp., on the other hand, 100% susceptible to AMC and 80% susceptible to Do, Te, ENR and UB was recognised. Lastly, Photobacterium damsela subsp. piscicida was showed 100fe susceptible to Amc and 86% susceptible to NOR, CIP ENR and UB. As a consequence, fish bacterial pathogens isolated from Kyeongnam area, especially Tongyeong-si, Geoje-si, and Goseong-gun, were showed highly resistant to a variety of antibiotics available in the field.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.182.1-182
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• 2005

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.36-43
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• 1999

A study on the hydrolysis of anchovy using proteolytic bacteria isolated from anchovy jeotkal (a salt-fermented fish) was carried out to develop a rapid process of liquefied anchovy jeotkal. Five kinds of proteolytic bacteria, such as Staphylococcus sp.-l, Photobacterium sp., Volcaniella sp., Staphylococcus sp.-2 and Bacillus sp., were isolated from the anchovy jeotka1 that fermented with $20\%$ NaCl at room temperature for 2 months. Those grew well at $40^{\circ}C$, pH 7.0 on TPY broth with $2.0\%$ NaCl. The optimal hydrolysis temperature, pH, time and proteolytic bacteria densities for hydrolysis of minced anchovy were$40^{\circ}C$, 7.0, 6 hours and $1.8\times10^8$ cells/g raw anchovy, respectively.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.885-892
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• 2011

The bacterial communities in the intestinal tracts of earthworm were investigated by culture-dependent and -independent approaches. In total, 72 and 55 pure cultures were isolated from the intestinal tracts of earthworms under aerobic and anaerobic conditions, respectively. Aerobic bacteria were classified as Aeromonas (40%), Bacillus (37%), Photobacterium (10%), Pseudomonas (7%), and Shewanella (6%). Anaerobic bacteria were classified as Aeromonas (52%), Bacillus (27%), Shewanella (12%), Paenibacillus (5%), Clostridium (2%), and Cellulosimicrobium (2%). The dominant microorganisms were Aeromonas and Bacillus species under both aerobic and anaerobic conditions. In all, 39 DNA fragments were identified by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Aeromonas sp. was the dominant microorganism in feeds, intestinal tracts, and casts of earthworms. The DGGE band intensity of Aeromonas from feeds, intestinal tracts, and casts of earthworms was 12.8%, 14.7%, and 15.1%, respectively. The other strains identified were Bacillus, Clostridium, Enterobacter, Photobacterium, Pseudomonas, Shewanella, Streptomyces, uncultured Chloroflexi bacterium, and uncultured bacterium. These results suggest that PCR-DGGE analysis was more efficient than the culturedependent approach for the investigation of bacterial diversity and the identification of unculturable microorganisms.

• Journal of Environmental Health Sciences
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• v.34 no.5
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• pp.387-394
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• 2008

The toxicity of methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA) and formaldehyde (FA) on the indigenous microbial community in forest soil was studied. MTBE, TBA and FA with different concentrations were added into microcosms containing forest soil samples. After 10 and 30 days, total viable cell number and dehydrogenase activity in the microcosms were evaluated. Bacterial communities in the microcosms were also analyzed using a denaturing gradient gel electrophoresis (DGGE). Dehydrogenase activity and total viable cell number were decreased according to the increase of MTBE, TBA and FA concentrations (P<0.05). FA toxicity was the highest, but TBA toxicity was the lowest. The results of principal component analysis using DGGE fingerprints showed that the microbial communities contaminated MTBE, TBA and FA were grouped by exposure time not exposure concentration. Dominant species in the microcosms were as follows: Photobacterium damselae sub sp. and Bacillus sp. KAR28 for MTBE; Mycobacterium sp. and Uncultured Clostridium sp. for TBA; and Uncultured Paenibacillaceae bacterium and Anxynobacillus, Flavithermus for FA.