• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.704-708
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• 1999

In addition to catalyzing the synthesis of glucan from sucrose as a primary reaction, glucansucrase also catalyzes the transfer of glucose from sucrose to other carbohydrates that are present or are added to the reaction digest. Using dextransucrase and altemansucrase, prepared from Leuconostoc mesenteroides B-742CBM and B-1355C, respectively, we modified the bacterial cellulose in Acetobacter xylinum ATCC10821 culture, and then produced a characteristic cellulose that is soluble and has a new structure. There were also some partially modified insoluble cellulose and oligosaccharides in the modification culture. After methylation and following acid hydrolysis of both the soluble and insoluble glucans, there were ($1{\rightarrow}4$) as well as ($1{\rightarrow}6$) and ($1{\rightarrow}3$) glycosidic linkages in the soluble glucan.

• Korean Journal of Organic Agriculture
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• v.11 no.4
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• pp.61-74
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• 2003

This study was conducted to screen the antagonistic bacteria which inhibit the growth of plant pathogen, fusarium wilt(Fusarium oxysporum) occurred in tomato plants in greenhouse. We isolated an effective bacterial strains and investigated into the antifungal activity of the antagonistic microorganism and it’s identification. Ten bacterial strains which strongly inhibited Fusarium oxysporum were isolated from the nature, and the best antagonistic bacterial strain designated as KC175, was selected. The antagonistic strain KC175 was identified to be the genus Bacillus sp. based on the morphological and biochemical characterization. The Bacillus sp. KC175 showed 58.2% of antifungal activity against the growth of Fusarium oxysporum. By the bacterialization of the culture broth and the heat bacterialization culture filtrate of it, Bacillus sp. KC175 showed 91% and 18% of antifungal activity, respectively.

• Microbiology and Biotechnology Letters
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• v.39 no.4
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• pp.374-381
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• 2011

The beneficial effects of Eisenia fetida on soil properties have been attributed to their interaction with soil microorganisms. The bacterial diversity of the intestinal tract of E. fetida was investigated by culture-dependent and culture-independent methods including denaturing gradient gel electrophoresis (DGGE) and pyrosequencing analyses. In a pure culture, Lysinibacillus fusiformis (51%), Bacillus cereus (30%), Enterobacter aerogenes (21%), and L. sphaericus (15%) were identified as the dominant microorganisms. In the DGGE analyses, B. cereus (15.1%), Enterobacter sp. (13.6%), an uncultured bacterium (13.1%), and B. stearothermophilus (7.8%) were identified as the dominant microorganisms. In the pyrosequencing analyses, Microbacterium soli (26%), B. cereus (10%), M. esteraromaticum (6%), and Frigoribacterium sp. (6%) were identified as the dominant microorganisms. The other strains identified were Aeromonas sp., Pseudomonas sp., Borrelia sp., Cellulosimicrobium sp., Klebsiella sp., and Leifsonia sp. The results illustrate that culture independent methods are better able to detect unculturable microorganisms and a wider range of species, as opposed to isolation by culture dependent methods.

• Journal of Animal Science and Technology
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• v.65 no.2
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• pp.387-400
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• 2023

Ruminal protozoa, especially entodiniomorphs, engulf other members of the rumen microbiome in large numbers; and they release oligopeptides and amino acids, which can be fermented to ammonia and volatile fatty acids (VFAs) by amino acid-fermenting bacteria (AAFB). Studies using defaunated (protozoa-free) sheep have demonstrated that ruminal protozoa considerably increase intraruminal nitrogen recycling but decrease nitrogen utilization efficiency in ruminants. However, direct interactions between ruminal protozoa and AAFB have not been demonstrated because of their inability to establish axenic cultures of any ruminal protozoan. Thus, this study was performed to evaluate the interaction between Entodinium caudatum, which is the most predominant rumen ciliate species, and an AAFB consortium in terms of feed degradation and ammonia production along with the microbial population shift of select bacterial species (Prevotella ruminicola, Clostridium aminophilum, and Peptostreptococcus anaerobius). From an Ent. caudatum culture that had been maintained by daily feeding and transfers every 3 or 4 days, the bacteria and methanogens loosely associated with Ent. caudatum cells were removed by filtration and washing. An AAFB consortium was established by repeated transfers and enrichment with casamino acids as the sole substrate. The cultures of Ent. caudatum alone (Ec) and AAFB alone (AAFB) and the co-culture of Ent. caudatum and AAFB (Ec + AAFB) were set up in three replicates and incubated at 39℃ for 72 h. The digestibility of dry matter (DM) and fiber (NDF), VFA profiles, ammonia concentrations, pH, and microscopic counts of Ent. caudatum were compared among the three cultures. The co-culture of AAFB and Ent. caudatum enhanced DM degradation, VFA production, and Ent. caudatum cell counts; conversely, it decreased acetate: propionate ratio although the total bacterial abundance was similar between Ec and the Ec + AAFB co-culture after 24 h incubation. The ammonia production and relative abundance of C. aminophilum and P. anaerobius did not differ between AAFB alone and the Ec + AAFB co-culture. Our results indicate that Ent. caudatum and AAFB could have a mutualistic interaction that benefited each other, but their interactions were complex and might not increase ammoniagenesis. Further research should examine how such interactions affect the population dynamics of AAFB.

• Korean Journal of Environmental Biology
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• v.41 no.3
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• pp.308-324
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• 2023

This study investigated unrecorded freshwater bacterial species in Korea. Water and sediment samples were collected from the Nakdong River basin from 2020-2022. Bacterial isolates obtained through the conventional culture method with commercial media were subjected to 16S rRNA gene sequencing to identify unrecorded bacterial species. Results of 16S rRNA gene sequencing of the bacterial isolates revealed that a total of 44 bacterial isolates shared 16S rRNA gene sequence similarities of more than 98.65%, with validly published bacterial species not reported in Korea yet. These isolates were phylogenetically assigned to 4 phyla, 7 classes, 21 orders, 33 families, and 42 genera. A total of 2, 6, 12, and 24 species belonged to phyla Bacillota, Bacteroidota, Actinomycetota, and Pseudomonadota, respectively. Here, we provide details of these 44 unrecorded bacterial species, including Gram staining, colony and cellular morphologies, biochemical properties, and phylogenetic position.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.1
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• pp.92-102
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• 2019

Objective: To investigate changes in rumen fermentation characteristics and bacterial community by a sudden change to a high concentrate diet (HC) in Korean domestic ruminants. Methods: Major Korean domestic ruminants (each of four Hanwoo cows; $545.5{\pm}33.6kg$, Holstein cows; $516.3{\pm}42.7kg$, and Korean native goats; $19.1{\pm}1.4kg$) were used in this experiment. They were housed individually and were fed ad libitum with a same TMR (800 g/kg timothy hay and 200 g/kg concentrate mix) twice daily. After two-week feeding, only the concentrate mix was offered for one week in order to induce rapid rumen acidosis. The rumen fluid was collected from each animals twice (on week 2 and week 3) at 2 h after morning feeding using an oral stomach tube. Each collected rumen fluid was analyzed for pH, volatile fatty acid (VFA), and $NH_3-N$. In addition, differences in microbial community among ruminant species and between normal and an acidosis condition were assessed using two culture-independent 16S polymerase chain reaction (PCR)-based techniques (terminal restriction fragment length polymorphism and quantitative real-time PCR). Results: The HC decreased ruminal pH and altered relative concentrations of ruminal VFA (p<0.01). Total VFA concentration increased in Holstein cows only (p<0.01). Terminal restriction fragment length polymorphism and real-time quantitative PCR analysis using culture-independent 16S PCR-based techniques, revealed rumen bacterial diversity differed by species but not by HC (p<0.01); bacterial diversity was higher in Korean native goats than that in Holstein cows. HC changed the relative populations of rumen bacterial species. Specifically, the abundance of Fibrobacter succinogenes was decreased while Lactobacillus spp. and Megasphaera elsdenii were increased (p<0.01). Conclusion: The HC altered the relative populations, but not diversity, of the ruminal bacterial community, which differed by ruminant species.

• Journal of Animal Science and Technology
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• v.55 no.1
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• pp.41-49
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• 2013

In vitro and in situ incubation studies were conducted to determine effects of yeast culture supplements (Saccharomyces cerevisiae) on cellulolytic bacterial function and fiber digestion in rice straw. In vitro dry matter digestibility of rice straw gradually increased according to supplemental levels of yeast culture (0.0, 0.2, 0.4, 0.6, 0.8 and 1.0%). Digestibility of rice straw started to increase apparently when yeast culture was added more than 0.6% level (p<0.05). Also, we reconfirmed that in vitro dry matter digestibility was significantly increased by 0.6% of yeast culture addition in 4% NaOH treated and non-treated rice straws (p<0.05). When in situ dry matter digestibility was tested in Korean native goats fed basal diet or experimental diet which contained 1.0% of yeast culture, the yeast culture feeding improved in situ dry matter digestibility in both 4% NaOH treated and non-treated rice straws (p<0.05). In case of real-time PCR monitoring cellulolytic bacterial function, the bacterial population attached on rice straw showed the increasing trends with higher level of yeast culture spraying on rice straw. F. succinogenes and R. flavefaciens were significantly increased in accordance to spraying levels of yeast culture (0.0, 0.1 and 0.3%) at both 12 and 24 hrs of in situ incubation (p<0.05). R. albus was significantly higher population in yeast culture spraying than non-soraying at 12 hrs of in situ incubation (p<0.05). These bacterial populations were showed the increasing trends with digestibility enhancement of rice straw according to the higher levels of yeast culture supplement. Overall, these results clearly suggest that the presence of yeast culture result in noticeable increase of rice straw digestion, which is modulated via good effect on cellulolytic bacterial attachment to fiber substrates.

• The Plant Pathology Journal
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• v.26 no.1
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• pp.90-92
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• 2010

Staining profiles and bacterial morphology were compared in Xanthomonas citri pv. citri by a transmission electron microscopy. Four types of negative staining regimes were employed depending on culture media and heavy metal stains. The bacterial cells grown on LB agar media often appeared clustered on the supporting film. Meanwhile, individual bacterial cells could be readily found on the preparations from LB broth media. Typical rod-shaped cells (ca. $1\;{\mu}m$ in length) and their flagella were observed in either 2% uranyl acetate (UA) or 2% neutralized potassium phosphotungstate (PTA) staining. The UA-stained bacteria often showed relatively intact cell morphology and rather positively stained cells with a thin electron-dense stain depth around bacteria. The PTA-stained bacteria were characterized by the wrinkled cell surface where the stain was entrapped in grooves. In addition, distinct electron-dense stain depth was evident around the PTA-stained preparations. Numerous fimbriae could be mostly observed from the PTA-stained preparations of the two culture media, but not from the UA-stained preparations.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.515-524
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• 2020

With the increasing demand for enzymes in industrial applications there is a growing need to easily produce industrially important microbial enzymes. This study was carried out to screen the indigenous refinery bacterial isolates for their production of two industrially important enzymes i.e. lipase and protease. A total of 15 bacterial strains were isolated using Soil Extract Agar media from the oil-contaminated environment and one was shown to produce high quality lipase and protease enzymes. The culture conditions (culture duration, temperature, source of nitrogen, carbon, and pH) were optimized to produce the optimum amount of both the lipase (37.6 ± 0.2 Uml-1) and the protease (41 ± 0.4 Uml-1) from this isolate. Productivity of both enzymes was shown to be maximized at pH 7.5 in a medium containing yeast extract and peptone as nitrogen sources and sucrose and galactose as carbon sources when incubated at 35 ± 1℃ for 48 h. Bacterial strain SAB06 was identified as Bacillus licheniformis (MT250345) based on biochemical, morphological, and molecular characteristics. Further studies are required to evaluate and optimize the purification and characterization of these enzymes before they can be recommended for industrial or environmental applications.

• Journal of Environmental Science International
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• v.14 no.12
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• pp.1163-1170
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• 2005

The microbial adsorption characteristics of two different media for biological treatment were studied using attached diverse microbes onto activated carbon and ceramic. The results in the experiments of the characteristics of physical adhesion on two different media with addition of high and low concentrated substrate in the culture were observed that the efficient of adhesion onto F-400 activated carbon was higher over that of ceramic due to the surface area of media. The irradiation treatment by ultrasonication with 400 W power and 3 min retention time on the media without addition substrate conditions and subsequent mixing throughly the culture showed the highest efficiency of cell detachment on the media. Three different microbes, P. ovalis, A calcoaceticus, and B. subtillis were used for the study of the characteristics of microbial adhesion on the media. p ovalis showed the highest adhesion capability while B. subtillis showed the lowest capability adhesion onto media either addition of substrate in the culture. The mixed bacterial culture showed $10\%$ lower removal efficiency of DOC in the low concentrated substrate culture compared to the single pure culture. Whileas, it did not show significant difference between two cultures at high concentrated substrate. It was also observed same population density of microorganism by counting of microbes adhered to microbial media with an ultrasound treatment.