• Asian-Australasian Journal of Animal Sciences
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• v.31 no.1
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• pp.63-70
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• 2018

Objective: The aim of the study was to isolate gossypol-degrading bacteria and to assess its potential for gossypol degradation. Methods: Rumen liquid was collected from fistulated cows grazing the experimental pasture. Approximately 1 mL of the rumen liquid was spread onto basal medium plates containing 2 g/L gossypol as the only source of carbon and was then cultured at $39^{\circ}C$ to isolate gossypol-degrading bacteria. The isolated colonies were cultured for 6 h and then their size and shape observed by microscope and scanning electron microscope. The 16S rRNA gene of isolated colonies was sequenced and aligned using National Center for Biotechnology Information-Basic Local Alignment Search Tool. The various fermentation conditions, initial pH, incubation temperature, inoculum level and fermentationperiod were analyzed in cottonseed meal (CSM). The crude protein (CP), total gossypol (TG), and free gossypol (FG) were determined in CSM after fermentation with isolated strain at $39^{\circ}C$ for 72 h. Results: Screening results showed that a single bacterial isolate, named Rumen Bacillus Subtilis (RBS), could use gossypol as a carbon source. The bacterium was identified by 16S rDNA sequencing as being 98% homologous to the sequence of Bacillus subtilis strain GH38. The optimum fermentation conditions were found to be 72 h, $39^{\circ}C$, pH 6.5, moisture 50%, inoculum level $10^7cell/g$. In the optimum fermentation conditions, the FG and TG content in fermented CSM decreased 78.86% and 49% relative to the control. The content of CP and the essential amino acids of the fermented CSM increased respectively, compared with the control. Conclusion: The isolation of a gossypol-degrading bacterium from the cow rumen is of great importance for gossypol biodegradation and may be a valuable potential source for gossypol-degradation of CSM.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.272-278
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• 2007

Proteases are enzymes that break peptide bonds between amino acids of other proteins and occupy a crucial position with respect to their applications in both physiological and commercial fields. In order to screen new source of protease, bacteria producing extracellular proteases at low temperature were isolated from deep sea water of East Sea, Korea. A bacterium showing the best growth rate and production of an extracellular protease at low temperature was designated HJ 47. The DNA sequence analysis of the 16S rRNA gene, phenotypic tests and morphology led to the placement of this organism in the genus Pseudoalteromonas. Although maximal growth was observed at $37^{\circ}C$, enzyme production per culture time was maximum at $20^{\circ}C$. At this temperature, extracellluar protease production was detected from the end of the exponential phage to stationary phase, and maximal at 15 hours after initial production. The optimum temperature and pH of the protease were found to be $35^{\circ}C$ and 8.

• Journal of Life Science
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• v.23 no.1
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• pp.110-115
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• 2013

A microorganism (strain AR1) producing an extracellular lipolytic enzyme was isolated from hot springs located in Beppu, Japan. Phylogenetic analysis based on the 16S rDNA sequence and biochemical studies indicated that AR1 belongs to the genus Geobacillus. This study focused on novel strategies to increase extracellular lipolytic enzyme production by this novel Geobacillus sp. AR1. Cultures of the AR1 strain grew within a wide temperature range (from 35 to $75^{\circ}C$); the optimum temperature was $65^{\circ}C$. The pH for optimal growth was 6.5, whereas the optimum pH for lipolytic enzyme production was 8.5. The presence of oils in the culture medium led to improvements in lipolytic enzyme activity. Soybean oil was the most efficient inducer, and it yielded better results when added in the exponential phase. On the other hand, the addition of chemical surfactants led to lipolytic enzyme production. Their addition to the culture could affect the location of the enzyme activity. The addition of Tween 20 in the stationary phase significantly increased the proportion of the extracellular enzyme activity. According to the results, following the addition of soybean oil and Tween 20 in the exponential and stationary phases, the extracellular lipolytic activity was increased 2.4-fold compared with that of a control.

• Journal of Life Science
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• v.26 no.2
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• pp.198-203
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• 2016

This study aimed to isolate a novel agarase-producing marine bacterium and characterize its agarase, as agarases are known to produce biofunctional agarooligosaccharides or neo-agarooligosaccharides. A novel agar-degrading bacterium, SH-2, was isolated from the seawater of Namhae in Gyeongnam Province, Korea, and cultured in Marine agar 2216 medium. The 16S rRNA gene sequence represented 99% identity with that of the members of the Marinomonas genus; hence, the isolated bacterium was named Marinomonas sp. SH-2. The crude agarase was prepared from a culture medium of Marinomonas. sp SH-2, and exhibited maximum agarase activity at 170.2 units/l. The optimum conditions were pH 6.0 and 30℃ in 20 mM Tris-HCl buffer. The agarase activity of the bacterium was highly elevated from 20℃(42% relative activity) to 30℃(100%), and 82% activity was shown at 40℃. Its relative activities were less than 40% at over 40℃ after a 0.5 hr exposure. Relative activity was 100% at pH 6.0, while it was 72% and 48% at pH 5.0 and pH 7.0, respectively. The enzyme from Marinomonas sp. SH-2 degraded agarose to neoagarohexaose and neoagarotetraose, indicating that the enzyme is β-agarase. Thus, Marinomonas sp. SH-2 and its enzyme could be practical for applications in food, cosmetic, and medical research.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.156-162
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• 2016

In this study, we isolated a new agar-degrading marine bacterium and characterized its agarase. An agardegrading marine bacterium SH-1 was isolated from seawater, collected from the seashore of Namhae in Gyeongnam province, Korea, and cultured in marine agar 2216 media. It was identified as Maribacter. sp. SH-1 by phylogenetic analyses, based on 16S rRNA gene sequence. The extracellular agarase was extracted from culture media of Maribacter sp. SH-1 and characterized. Its relative activities were 56, 62, 94, 100, and 8% at 20, 30, 40, 50, and 60℃, respectively, whereas 15, 100, 60, and 21% relative activities were observed at pH 5, 6, 7, and 8, respectively. Its extracellular agarase exhibited maximum activity (231 units/l) at pH 6.0 and 50℃, in 20 mM Tris-HCl buffer. Therefore, this agarase would be applicable as it showed the maximum activity at the temperature at which the agar is in a sol state. Furthermore, the agarase activities remained over 90% at 20, 30, and 40℃ after 0.5 h exposure at these temperatures. Thin layer chromatography analysis suggested that Maribacter sp. SH-1 produces extracellular β-agarase, as it hydrolyzes agarose to produce neoagarooligosaccharides, such as neoagarohexaose (34.8%), neoagarotetraose (52.2%), and neoagarobiose (13.0%). Maribacter sp. SH-1 and its β-agarase would be useful for the production of neoagarooligosaccharides, which shows functional properties, like skin moisturizing, skin whitening, inhibition of bacterial growth, and delay in starch degradation.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.364-373
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• 2015

As an effort to utilize alginate, 103 bacterial isolates that were positive for the alginate lyase activity were isolated from various clams and seawater samples collected in Incheon coastal area. Among them, 3 strains (M1-2-1, M6-1, and C8-15) were finally selected for further analysis based on their activities at higher levels than others. These isolates were all Gram-negative and rod shaped halophilic bacteria with motility. According to their physiological and biochemical properties as well as DNA sequence of their 16S rRNA genes, M1-2-1 and M6-1 were identified as a member of genus Pseudoalteromonas and C8-15 belonged to genus Vibrio. They exhibited the alginate degrading activity at the maximal level when they were cultured in APY broth for 6-8 h at $25^{\circ}C$. Both their growth and the enzyme activity were greatly enhanced when NaCl was added to the growth medium. The crude alginate lyases from the supernatants of the bacterial cultures showed the highest activity at $45^{\circ}C$ and pH 7.0-8.0. M1-2-1 and M6-1 produced 2.723 and 1.976 g/L of reducing sugar from alginate, respectively, suggesting that they have potential for commercial application.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1292-1298
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• 2023

PAMB 00755^T, a bacterial strain, was isolated from Korean fir leaves. The strain exhibits yellow colonies and consists of Gram-negative, non-motile, short rods or ovoid-shaped cells. It displays optimal growth conditions at 20℃, 0% NaCl, and pH 6.0. Results of 16S rRNA gene-based phylogenetic analyses showed that strain PAMB 00755^T was most closely related to Sphingomonas chungangi MAH-6^T (97.7%) and Sphingomonas polyaromaticivorans B2-7^T (97.4%), and ≤96.5% sequence similarity to other members of the genus Sphingomonas. The values of average nucleotide identity (79.9-81.3%), average amino acid identity (73.3-75.9%), and digital DNA-DNA hybridization (73.3-75.9%) were significantly lower than the threshold values for species boundaries; these overall genome-related indexes (OGRI) analyses indicated that the strain represents a novel species. Genomic analysis revealed that the strain has a 4.4-Mbp genome encoding 4,083 functional genes, while the DNA G+C content of the whole genome is 66.1%. The genome of strain PAMB 00755^T showed a putative carotenoid biosynthetic cluster responsible for its antioxidant activity. The respiratory quinone was identified as ubiquinone 10 (Q-10), while the major fatty acids in the profile were identified as C_18:1ω7c and/or C_18:1ω6c (summed feature 8). The major polar lipids of strain PAMB 00755^T were diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, and phosphatidylcholine. Based on a comprehensive analysis of genomic, phenotypic, and chemotaxonomic characteristics, we proposed the name Sphingomonas abietis sp. nov. for this novel species, with PAMB 00755^T as the type strain (= KCTC 92781^T = GDMCC 1.3779^T).

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.437-443
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• 2013

The diversity of culturable non-actinobacterial (NA) bacteria associated with four species of South China Sea gorgonians was investigated using culture-dependent methods followed by analysis of the bacterial 16S rDNA sequence. A total of 76 bacterial isolates were recovered and identified, which belonged to 21 species of 7 genera, and Bacillus was the most diverse genus. Fifty-one percent of the 76 isolates displayed antibacterial activities, and most of them belonged to the Bacillus genus. From the culture broth of gorgonian-associated Bacillus methylotrophicus SCSGAB0092 isolated from gorgonian Melitodes squamata, 11 antimicrobial lipopeptides including seven surfactins and four iturins were obtained. These results imply that Bacillus strains associated with gorgonians play roles in coral defense mechanisms through producing antimicrobial substances. This study, for the first time, compares the diversity of culturable NA bacterial communities among four species of South China Sea gorgonians and investigates the secondary metabolites of gorgonian-associated B. methylotrophicus SCSGAB0092.

• Mycobiology
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• v.36 no.1
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• pp.13-18
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• 2008

Eight distinct bacteria were isolated form diseased mycelia of the edible mushroom, Pleurotus eryngii. 16S rDNA sequence analysis showed that the isolates belonged to a variety of bacterial genera including Bacillus (LBS5), Enterobacter (LBS1), Sphingomonas (LBS8 and LBS10), Staphylococcus (LBS3, LBS4 and LBS9) and Moraxella (LBS6). Among them, 4 bacterial isolates including LBS1, LBS4, LBS5, and LBS9 evidenced growth inhibitory activity on the mushroom mycelia. The inhibitory activity on the growth of the mushroom fruiting bodies was evaluated by the treatment of the bacterial culture broth or the heat-treated cell-free supernatant of the broth. The treatment of the culture broths or the cell-free supernatants of LBS4 or LBS9 completely inhibited the formation of the fruiting body, thereby suggesting that the inhibitory agent is a heat-stable compound. In the case of LBS5, only the bacterial cell-containing culture broth was capable of inhibiting the formation of the fruiting body, whereas the cell-free supernatant did not, which suggests that an inhibitory agent generated by LBS5 is a protein or a heat-labile chemical compound, potentially a fungal cell wall-degrading enzyme. The culture broth of LBS1 was not inhibitory. However, its cell-free supernatant was capable of inhibiting the formation of fruiting bodies. This indicates that LBS1 may produce an inhibitory heat-stable chemical compound which is readily degraded by its own secreted enzyme.

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.256-263
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• 2012

A strain of bacterium producing antifungal antibiotic was isolated and identification of the strain was attempted. We could identify the bacterium as being a Bacillus sp., based on morphological observation, physiological characteristics, and 16S rDNA sequence analysis, thus leading us to designate the strain as Bacillus sp. AH-E-1. The strain showed potent antibiotic activity against phytopathogenic and human pathogenic fungi by inducing mycelial distortion and swelling and inhibiting spore germination. The antibiotic metabolite produced by the strain demonstrated excellent thermal and pH (2-11) stability, but was labile to autoclaving. From these results, we could find a broader antifungal activity of Bacillus genus. Isolation and characterization of the active agent produced by the strain are under progress.