• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.17-20
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• 2001

Whole-cell attachment by covalent linkage, thereby simulating natural and specific attachments, improves the osmotolerance of Saccharomyces cerevisiae cells. The enhanced osmoresistance is correlated with a decrease in the intercellular concentration of trehalose and accompanied by membrane compositional changed. The results obtained indicate that yeast cell-support (physical) contact is sensed and responded to.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.273-278
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• 1985

새로운 페니실린 발효방법으로서, Penicillin chrysogenum의 포자를 담체의 미세구멍 조직에 흡착시킨 후 배양하여 얻은 균사증식담체를 이용하여 페니실린 발효를 시도하였다. 고정화 담체로써는 Celite가 가장 효율적이었으며, 이때 균사는 담체의 내부에서부터 포자가 발아하여 담체의 표면에서 증식하기 때문에 매우 안정된 biofilm growth를 얻을 수 있었다. 프라스크 배양에서 담체의 양을 5-10% 첨가하였을 때 세포의 증식과 페니실린의 생산이 전통적인 dispersed filamentous growth 에 의한 발효방법보다 현저히 증가되었다. 그러나 두 경우 모두 세포의 활성은 1900 unit/mg-cellㆍhr로 일정하였다. 균사증식 담체를 이용하여 유동층 발효조에서 반연속식으로 발효를 진행시킨 결과 페니실린의 연속생산이 가능함을 발견하였다. 그러나 발효조내에서 biofilm growth시 film두께의 조절과 페니실린 생산성을 일정수준으로 오랫동안 유지시킬 수 있는 방법이 앞으로 연구되어야 할 것으로 판단되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.348-352
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• 2005

In this study, fermentation using a rotary biofilm contactor was conducted to improve bacterial cellulose production. We investigated the optimal fermentation conditions by using a newly isolated Gluconacetobacter sp. RKY5 in the rotary biofilm contactor. The optimal total area of discs was found to be 1,769 $cm^2$ at which bacterial cellulose and cell concentration was obtained to 5.52 g/L and 4.98 g/L, respectively. In case of aeration experiment, when the aeration rate was 1.25 vvm, the maximal bacterial cellulose (5.67 g/L) was obtained and cell concentration was 5.25 g/L.

• Journal of Microbiology and Biotechnology
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• 제29권11호
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• pp.1749-1759
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• 2019

Aspergillus ochraceus biofilm, developed on an inert support, can produce tannase in Khanna medium containing 1.5% (w/v) tannic acid as the carbon source, at an initial pH of 5.0, for 72 h at 28℃. Addition of 0.1% (w/v) yeast extract increased enzyme production. The enzyme in the crude filtrate exhibited the highest activity at 30℃ and pH 6.0. At 50℃, the half-life (T50) was 60 min and it was 260 min at pH 6.0. In general, addition of detergents and surfactants did not affect tannase activity significantly. Tannase has potential applications in various biotechnological processes such as the production of propyl gallate and in the treatment of tannin-rich effluents. The content of tannins and total phenolic compounds in effluents from leather treatment was reduced by 56-83% and 47-64%, respectively, after 2 h of enzyme treatment. The content of tannins and total phenolic compounds in the sorghum flour treated for 120 h with tannase were reduced by 61% and 17%, respectively. Interestingly, the same A. ochraceus biofilm was able to produce tannase for three sequential fermentative process. In conclusion, fungal biofilm is an interesting alternative to produce high levels of tannase with biotechnological potential to be applied in different industrial sectors.

• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.1829-1835
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• 2016

Dental caries is caused by cariogenic biofilm, an oral biofilm including Streptococcus mutans. Recently, the prevention of dental caries using various probiotics has been attempted. Lactococcus lactis HY 449 is a probiotic bacterium. The aim of this study was to investigate the effect of L. lactis HY 449 on cariogenic biofilm and to analyze its inhibitory mechanisms. Cariogenic biofilm was formed in the presence or absence of L. lactis HY 449 and L. lactis ATCC 19435, and analyzed with a confocal laser microscope. The formation of cariogenic biofilm was reduced in cultures spiked with both L. lactis strains, and L. lactis HY 449 exhibited more inhibitory effects than L. lactis ATCC 19435. In order to analyze and to compare the inhibitory mechanisms, the antibacterial activity of the spent culture medium from both L. lactis strains against S. mutans was investigated, and the expression of glucosyltransferases (gtfs) of S. mutans was then analyzed by real-time RT-PCR. In addition, the sucrose fermentation ability of both L. lactis strains was examined. Both L. lactis strains showed antibacterial activity and inhibited the expression of gtfs, a nd t he d ifference b etween both strains did not show. In the case of sucrose-fermenting ability, L. lactis HY 449 fermented sucrose but L. lactis ATCC 19435 did not. L. lactis HY 449 inhibited the uptake of sucrose and the gtfs expression of S. mutans, whereby the development of cariogenic biofilm may be inhibited. In conclusion, L. lactis HY 449 may be a useful probiotic for the prevention of dental caries.

• 한국습지학회지
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• 제9권1호
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• pp.115-121
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• 2007

A novel hydrogen fermentation technique by using polyvinyl alcohol (PVA) gel beads as a biomass carrier was investigated. The hydrogen gas was stably produced throughout the experimental period in a continuous reactor. Even though the hydrogen productivity was suddenly decrease by experimental troubles, the bacteria attached to the PVA gel beads played as an inoculum, it was promptly recovered. The hydrogen yield per glucose was not very high ($1.0-1.2mol-H_2/mol-glucose$), thus the optimization of the experimental conditions such as ORP and HRT should be considered to improve the hydrogen productivity. Bacterial community was stable during experimental period after the PVA gel beads applying, which indicated that applying of biomass carrier was specific to keep not only the biomass but also the bacteria commonly. Clostridium species were phylogenetically detected, which suggested that these bacteria contributed to the hydrogen production in the biofilm attached to the PVA gel beads.

• 미생물학회지
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• 제55권3호
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• pp.293-295
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• 2019

메주로부터 분리한 Enterococcus faecalis DM01 균주는 8종의 항생제(ampicillin, chloramphenicol, ciprofloxacin, erythromycin, gentamicin, penicillin G, tetracycline, vancomycin) 저항성, 바이오필름 및 용혈현상을 나타내지 않았다. GC 함량 37.68%, 2,785,968 bp 크기의 단일 chromosome을 보유하고 있는 DM01 균주의 유전체 정보는 콩발효식품 제조용 종균 적용에 요구되는 항생물질 저항성, 바이오필름 및 용혈현상 관련의 안전성을 뒷받침하는 것으로 확인되었다.

• Journal of Microbiology
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• 제38권2호
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• pp.99-104
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• 2000

Hydrogen peroxide has been used in cleaning the piping of an advanced high-purity water system that supplies ultra-high purity water (UHPW) for 16 megabyte DRAM semiconductor manufacturing. The level of hydrogen peroxide-resistant bacteria in UHPW water was monitored prior to and after disinfecting the piping with hydrogen peroxide. Most of the bacteria isolated after hydrogen peroxide disinfection were highly resistant to hydrogen peroxide. However, the percentage of resistant bacteria decreased with time. The hydrogen peroxide-resistant bacteria were identified as Micrococcus luteus, Bacillus cereus, Alcaligenes latus, Xanthomonas sp. and Flavobacterium indologenes. The susceptibility of the bacteria to hydrogen peroxide was tested as either planktonic cells or attached cells on glass. Attached bacteria as the biofilm on glass exhibited increased hydrogen peroxide resistnace, with the resistance increasing with respect to the age of the biofilm regrowth on piping after hydrogen peroxide treatment. In order to optimize the cleaning strategy for piping of the high-purity water system, the disinfecting effect of hydrogen preoxide and peracetic acid on the bacteria was evaluated. The combined use of hydrogen peroxide and peracetic acid was very effective in killing attached bacteria as well as planktonic bacteria.

• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.554-558
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• 2000

Bacteria were isolated and identified from an advanced high-purity water system that supplies ultra-high purity water (UHPW) for 16-megabyte DRAM semiconductor manufacturing. Scanning electron microscopic and microbiological observations revealed that the primary source of the bacteria isolated from the UHPW was detached cells from biofilms developed on the pipe wall through which the UHPW, a man-made and extremely nutrient poor environment, was passing. About 63-65% of the bacteria isolated from the UHPW and the pipe wall were Gram-positive, whereas only 10% of the bacteria isolated from the feed water were Gram-positive. The of Gram-positive bacteria and seven genera of Gram-negative bacteria. Strains of the UHPW bacteria effectively adhered to and formed a biofilm on the surface of polyvinyl chloride (PVC) pipe.

• 미생물학회지
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• 제54권4호
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• pp.453-455
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• 2018

된장으로부터 콩발효 종균후보 Bacillus licheniformis 0DA23-1가 분리되었다. 0DA23-1 균주는 GC 함량 45.96%, 약 4.4 Mb 크기의 단일 chromosome을 보유하고 있었고, 식중독균 Bacillus cereus 및 Staphylococcus aureus가 보유한 위해성 유전자는 유전체로부터 확인되지 않았다. 또한, 8종의 항생물질(chloramphenicol, clindamycin, erythromycin, gentamicin, kanamycin, streptomycin, tetracycline, vancomycin) 저항성 및 혈청분해 활성, 바이오필름 생성 관련 유전자도 확인되지 않았다.