• Journal of Life Science
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• v.22 no.3
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• pp.306-311
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• 2012

A gene encoding a lipase, lipT, was cloned from the psychrotrophic bacterium Pseudomonas mandelii and sequenced. An open reading frame of 1,686 bp was found that encodes a polypeptide consisting of 562 amino acid residues. Sequence analysis revealed a Gly-His-Ser-Leu-Gly sequence, which matches the consensus Gly-X-Ser-X-Gly motif conserved among lipolytic enzymes. The recombinant LipT protein was predominantly expressed as inclusion bodies in Escherichia coli and subsequently purified by nickel-chelate affinity chromatography. A small fraction of LipT was refolded, and the subsequent LipT exhibited substrate preferences for p-nitrophenyl butyrate (C4) and p-nitrophenyl octanoate (C8).

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.74-81
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• 1993

To investigate the oil degrading properties of psychrotrophic bacterium Acinetobacter calcoaceticus Al-l the effects of environmental factors on this bacterium were studied. The optimal environmental conditions for cell growth rate and oil-emulsifying activity were as follows; temperature $15^{\circ}C$, pH 7.5, salt concentration 0- 3% and crude oil concentration 0.1%. Additionally the optimal concentration of Nand P source for cell growth rate and oil-emulsifying activity were 0.76 mM and 0.057 mM as $(NH_4)HS0_4$ and $K_2HP0_4$, respectively. Analysis of remnant oil by gas chromatography showed time dependent oil degradation pattern by A. calcoaceticus during cultivation; At lOoe and $15^{circ}$e, most alkane peaks were disappeared and it showed large quantities of crude oil were degraded. But at $25^{circ}$e alkane compounds in the crude oil were partially degraded even after 120 hours incubation.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1135-1139
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• 2005

Psychrotrophic phenanthrene-degrading bacteria were identified in the sediment samples collected from Lake Baikal, Russia. Among 70 phenanthrene-degrading isolates, the seven that had the highest phenanthrene-degradation rates were identified by 16S rDNA sequencing. Isolate P25, identified as the Gram-positive rod-shaped organism Rhodococcus erythropolis, had the highest growth and degradation rate at $15^{\circ}C$. It could remove $26.0\%$ of 100 mg $1^{-1}$ phenanthrene in 20 days at $15^{\circ}C$, and degradation was less at $5^{\circ}C\;and\;25^{\circ}C$. The addition of surfactants to enhance degradation was tested. Brij 30 and Triton X-100 inhibited degradation at all surfactant concentrations tested, but Tween 80 stimulated phenanthrene degradation, especially at low concentrations. When $20{\times}$ CMC (critical micelle concentration) of Tween 80 was added, $38.0\%$ of 100 mg $1^{-1}$ phenanthrene was degraded in 12 days at $15^{\circ}C$. This psychrotrophic phenanthrene-degrading bacterium is a candidate for use in bioremediation of polycyclic hydrocarbon contamination in low temperature environments.

• Journal of Life Science
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• v.25 no.2
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• pp.174-179
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• 2015

The presence of psychrotrophic bacteria downgrades the quality of dairy products. This study evaluated the effect of lipolytic psychrotrophic bacteria on the chemical properties of Gouda cheese made from raw milk experimentally inoculated with a psychrotrophic bacterium (Acinetobacter genomospecies 10). Raw milk experimentally inoculated with Acinetobacter genomospecies 10 and refrigerated at $4^{\circ}C$ for 3 or 6 days produced a 6-week ripened Gouda cheese with a significant decrease in total solids (p<0.05) or an increased fat content (p<0.05), respectively. Raw milk inoculated with Acinetobacter genomospecies 10 and refrigerated for 3 days had higher (p<0.05) SCFFA (1.35 times), MCFFA (1.42 times), and LCFFA (1.44 times) than the control 6-week ripened Gouda cheese. The cheese manufactured from the inoculated and refrigerated raw milk had higher (p<0.05) total free fatty acids (1.68 times) compared with the control. Raw milk inoculated with Acinetobacter genomospecies 10 and refrigerated for 6 days had increased SCFFA (1.45 times), MCFFA (1.28 times), and LCFFA (1.38 times) compared with the control 6-weeks ripened Gouda cheese. The 6-week ripened Gouda cheese manufactured from this inoculated milk had higher (p<0.05) total free fatty acids (1.34 times) compared with the control. The results indicated that the production of excessive free fatty acids in dairy products by psychrotrophic bacteria can be critical in predisposing dairy products to off-flavors and in turn degrading their quality.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.254-259
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• 2002

A psychrotrophic bacterium was isolated from Antarctic marine sediment and identified as Shewanella sp. species based on the biochemical properties and 16S rRNA sequence, and designated as Shewanella sp. L93. Extracellular protease produced by this strain was purified through ammonium sulfate precipitation, High-Q column chromatography, first gel permeation chromatography, BioScale Q2 ion exchange chromatography and second gel permeation chromatography, and basic properties of this enzyme were investigated.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1217-1226
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• 2004

A psychrotrophic bacterial strain, Pseudomonas fluorescens BM07, synthesized unsaturated fatty acids (UFA) from fructose in response to lowering of growth temperature, and incorporated them into both polyhydroxyalkanoic acid (PHA) and membrane lipid. The blocking of PHA synthesis by adding 5 mM 2-bromooctanoic acid to the growth medium, containing 70 mM fructose, was found to be a useful means to profile the composition of membrane lipid by gas chromatography. As the growth temperature changed from 35 to $50^{\circ}C$, the total content of two UFA, 3-hydroxy-cis-5­dodecenoic acid ($C_{12:1}$) and 3-hydroxy-cis-7-tetradecenoic acid ($C_{14:1}$), in PHA increased from 31 to 44 $mol\%$. The growth at lower temperatures also led to an increase in the level of two major UFA, palmitoleic acid (C16:1 cis9) and cis-vaccenic acid (C18:1 cis11), in membrane lipid. A fraction of these membrane-lipid UFA was converted to their corresponding cyclopropane fatty acids (CFA). The CFA conversion was a function of culture time, exhibiting biphasic increase before and after entering the stationary phase. However, pH changes in growth media had no effect on the CFA conversion, which is contrary to the case of E. coli reported. The cells grown at $30^{\circ}C$ responded to a cold shock (lowering the medium temperature down to $10^{\circ}C$) by increasing the level of C16:1 cis9 and C 18: I cis II up to that of $10^{\circ}C$-grown control cells and concomitantly decreasing the relative level of cis-9,10­methylenehexadecanoic acid (the CFA converted from C16:1 cis9) from 14 to 8 $mol\%$, whereas the 10-grown cells exhibited little change in the lipid composition when exposed to a warmer environment of $30^{\circ}C$ for 12 h. Based on this one- way response, we suggest that this psychrotrophic strain responds more efficiently and sensitively to a cold shock than to a hot shock. It is also suggested that BM07 strain is a good producer of two unsaturated 3-hydroxyacids, $C_{12:1}\;and\;C_{141:1}$.

• Microbiology and Biotechnology Letters
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• v.35 no.1
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• pp.66-72
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• 2007

Yam has been recognized as healthy food due to its various biological activities, such as anti-obesity, antimicrobial, anticancer and immune-stimulation activities. In this study, antibacterial activities of 800 more natural plant extracts against yam-putrefactive psychrotrophic bacterium, Pseudomonas rhodesiae YAM-12, were evaluated to select a natural preservative, which is useful to long-term storage of yam and fresh-cut production. Finally, the clove oil was selected, and applied for the production of yam fresh-cut. The 1% of clove oil treated fresh-cut showed minor color changes during 31 days storage at $4^{\circ}C$ and the microbial growth was not detected. When the artificially contaminated fresh cut by dipping with P. rhodesiae YAM-12 suspension for 3 min was treated 1% clove oil, the microbial growth was identified to $10^4$ CFU/g from $10^3$ CFU/g with minor color changes. Whereas, treatment of sterilized water, or 100 ppm NaOCl into artificially contaminated fresh cut showed severe putrefaction $(10^8\;CFU/g)$ and color changes. Considering the previous reports that clove oil has antimicrobial, antioxidation, and antithrombosis activity, the use of clove oil into the yam fresh cut will provide market safety and consumer acceptability by prevention of microbial putrefaction and its biological activity.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.605-612
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• 2006

A psychrotrophic bacterium was isolated from oil-contaminated groundwater and identified as Rhodococcus sp. YHLT-2. Growth was observed at the temperature of 4 to $30^{\circ}C$. This strain degraded various petroleum hydrocarbons such as crude oil, diesel oil, and gasoline over the whole range of temperatures tested. The Rhodococcus sp. YHLT-2 was capable of growing even at $4^{\circ}C$, exhibiting 90% of oil biodegradation after 20 days. Degradation of crude oil occurred at low temperature in nature. This strain was also able to grow at 7% NaCl, and utilized not only short chain alkenes $(C_9\;to\;C_{12})$, but also a broad range of long chain alkenes $(C_{19}\;to\;C_{32})$ present in crude oil at $4^{\circ}C$. The Rhodococcus sp. YHLT-2 is expected to be of potential use in the in situ bioremediation of hazardous hydrocarbons under low-temperature and high-salt conditions.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.66-73
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• 1993

Psychrotrophic bacterial strains utilizing crude oil as their sole carbon and energy sources were isolated from Antarctic soil and sea sediments. One of the strains named AI-I showed the hightest activity for emulsification of crude oil and the best growth. This strain was identified as Acinetobacter calcoaceticus. A. calcoaceticus AI-I strain contains a plasmid (OCT plasmid) which was related to the utilization of alkane compounds. The molecular weight of this plasmid was estimated to be about 110 Md by agarose gel electrophoresis. The cured strain of A. calcoaceticus AI-I strain (OCT ) was not able to utilize normal hydrocarbon compounds ($C_6C_{17}$) as carbon and energy sources. A. ca/coaceticus AI-1 was resistant to ampicillin and sensitive to streptomycin, kanamycin, chloramphenicol, tetracycline. The results suggested that this strain carries a plasmid (OCT) responsible for oil utilization which is quite stable and might be concerned with antibiotics resistancy.

• Food Science of Animal Resources
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• v.36 no.4
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• pp.452-457
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• 2016

Lactoferrin is a glycoprotein with various biological effects, with antibacterial activity being one of the first effects reported. This glycoprotein suppresses bacterial growth through bacteriostatic or bactericidal action. It also stimulates the growth of certain kinds of bacteria such as lactic acid bacteria and bifidobacteria. In this study, Asn-Leu-Asn-Arg was selected and chemically synthesized based on the partial sequences of bovine lactoferrin tryptic fragments. Synthetic Asn-Leu-Asn-Arg suppressed the growth of Pseudomonas fluorescens, P. syringae and Escherichia coli. P. fluorescens is a major psychrotrophic bacteria found in raw and pasteurized milk, which decreases milk quality. P. syringae is a harmful infectious bacterium that damages plants. However, synthetic Asn-Leu-Asn-Arg did not inhibit the growth of Lactobacillus acidophilus. It is expected that this synthetic peptide would be the first peptide sequence from the bovine lactoferrin C-lobe that shows antibacterial activity.