• Journal of Microbiology and Biotechnology
• /
• 제33권6호
• /
• pp.771-779
• /
• 2023

Biofilms are a significant concern in the food industry. The utilization of plant-derived compounds to inactivate biofilms on food contact surfaces has not been widely reported. Also, the increasing negative perception of consumers against synthetic sanitizers has encouraged the hunt for natural compounds as alternatives. Therefore, in this study we evaluated the antimicrobial activities of ethanol extracts, acetone extracts, and essential oils (EOs) of seven culinary herbs against Salmonella enterica serotype Typhimurium and Listeria innocua using the broth microdilution assay. Among all tested extracts and EOs, the ethanol extract of Piper betle L. exhibited the most efficient antimicrobial activities. To evaluate the biofilm inactivation effect, S. Typhimurium and L. innocua biofilms on pitted and smooth stainless steel (SS) coupons were exposed to P. betle ethanol extract (12.5 mg/ml), sodium hypochlorite (NaClO; 200 ppm), hydrogen peroxide (HP; 1100 ppm), and benzalkonium chloride (BKC; 400 ppm) for 15 min. Results showed that, for the untreated controls, higher sessile cell counts were observed on pitted SS versus smooth SS coupons. Overall, biofilm inactivation efficacies of the tested sanitizers followed the trend of P. betle extract ≥ BKC > NaClO > HP. The surface condition of SS did not affect the biofilm inactivation effect of each tested sanitizer. The contact angle results revealed P. betle ethanol extract could increase the surface wettability of SS coupons. This research suggests P. betle extract might be utilized as an alternative sanitizer in food processing facilities.

• Journal of Microbiology and Biotechnology
• /
• 제25권4호
• /
• pp.554-558
• /
• 2015

Drug delivery systems (DDSs) incorporating bacterial minicells have been evaluated as a very powerful tool in view of biocompatibility. However, limited studies have been carried out on these systems, mainly using minicells from Salmonella sp. and Escherichia coli. Thus, we generated a new minicell-producing strain from an endotoxin-free Corynebacterium glutamicum by the inactivation of genes related to cell division. The two knockout strains, ${\Delta}parA$ and ${\Delta}ncgl1366$, showed distinct abilities to produce minicells. The resulting minicells were purified via sequential antibiotic treatments and centrifugations, which resulted in reproducible yields.

• 한국식품조리과학회지
• /
• 제26권6호
• /
• pp.848-852
• /
• 2010

This study investigated the antibacterial activities of extracts and fractions of Sasa borealis against eight bacteria (Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Psedomonas aerginosa, Salmonella choleraesuis, Serratia marcescens and Vibrio vulnificus) by broth dilution assay. Using survival curves, the kinetics of bacterial inactivation upon exposure to the extracts and fractions were followed for 24 h. In this same manner, MIC (minimum inhibitory concentration) values were determined by broth microdilution assay and then confirmed to be the extract concentrations that inhibited bacterial growth. Sasa borealis extracts showed antibacterial activities against all tested bacteria. In particular, all tested fractions of Sasa borealis had stronger activities than 70% ethanol extract. MIC of Sasa borealis extract was determined to be 5 mg/mL against Salmonella choleraesuis. All fractions of Sasa borealis extract had extremely strong antibacterial activities. MIC of fractions were determined to be 0.03~2.5 mg/mL. These results suggest that the extracts and fractions of Sasa borealis effectively inhibited bacterial growth and thus are useful as natural antibacterial agents.

• Journal of Microbiology and Biotechnology
• /
• 제28권8호
• /
• pp.1233-1246
• /
• 2018

Vibrio parahaemolyticus contamination causes serious foodborne illness and has become a global health problem. As a disinfectant, aqueous ozone can effectively kill a number of bacteria, viruses, parasites, and other microorganisms. In this study, three factors, namely, the aqueous ozone concentration, the exposure time, and the bacterial density, were analyzed by response surface methodology, and the aqueous ozone concentration was the most influential factor in the sterilization ratio. Under low aqueous ozone concentrations (less than 0.125 mg/l), the bacterial cell membranes remained intact, and the ozone was detoxified by intracellular antioxidant enzymes (e.g., superoxide dismutase and catalase). Under high aqueous ozone concentrations (more than 1 mg/l), cell membranes were damaged by the degree of peripheral electronegativity at the cell surface and the concentration of lactate dehydrogenase released into the extracellular space, and the ultrastructures of the cells were confirmed by transmission electron microscopy. Aqueous ozone penetrated the cells through leaking membranes, inactivated the enzymes, inhibited almost all the genes, and degraded the genetic materials of gDNA and total RNA, which eventually led to cell death.

• Journal of Applied Biological Chemistry
• /
• 제62권2호
• /
• pp.181-186
• /
• 2019

본 연구에서는 460 nm 파장의 청색 가시광선을 압출 떡의 표면에 조사하기 위하여 장치의 최적 디자인을 시뮬레이션을 통하여 확인하고 청색광이 압출 떡의 표면에서 식품 위해균인 B. cereus group에 미치는 영향을 확인하였다. LED 장치에서 광원모듈의 세 가지 배열(centered, cross, evenly spaced) 및 광원과 샘플 표면 사이의 거리(22, 32, 42 mm)에 따른 조사 면적에서 빛의 세기 패턴을 시뮬레이션을 통하여 계산하고, Petri factor를 통하여 균일도를 확인하였다. LED 배열의 균일도는 evenly spaced 배열에서 가장 균일한 패턴을 보였으며, 광원과의 거리가 32 및 42 mm일 경우 Petri factor가 0.9 이상으로 높은 균일도를 나타내었다. 떡볶이 떡에 LED 청색광을 조사한 경우 24 h 후 균 수가 초기 균 수에 비하여 감소하였으며, LED를 조사하지 않은 대조군에서는 초기 균 수가 증가하여 1.21 log CFU/g의 차이를 보였다. LED 조사 시 광원과 샘플의 거리가 증가할수록 Petri factor는 증가하나 감균 효과가 낮아지는 결과를 나타내었다. 따라서 Petri factor가 0.9 이상임을 만족하는 evenly spaced 배열의 32 mm 거리가 떡의 유통기한 연장을 위한 LED 장치의 디자인에 적합함을 확인하였다.

• 대한수의학회지
• /
• 제10권1호
• /
• pp.5-10
• /
• 1970

Due to the fact that an inactivated anthrax vaccine may lark its immunogenicity and stability of immunogen a number of spore vaccines were exclusively used worldwide. In these studies a number of important factors were emphasized to achieve the following: selection of non or less allergic strain of anthrax bacillus, capsulation of bacteria. obtaining of non sporulating but vegetative organisms, adequate inactivation of B. anthraccis by means of formalin, adsorption of immunogen to aluminum hydroxide gel. Non or less allergic strains of anthrax bacillus which is inactivated with formalin was selected by a hyperimmunization and shock test in rabbits. Obtaining capsular material and vegetative immunogen, a virulent anthrax organisms were cultivated on sodium bicarbonate medium with of without adding of l-alanine in which B, anthracis grew luxuriantly without forming spores. Inactivation was carried out at $37^{\circ}C$ water bath for 3 days after the bacterial culture was mixed with formalin, in a final concentration of two per cent of formalin. Aluminum hydroxide gel was added to the mixture of anthrax and blackleg bacterin. Vaccines were injected guinea pig via subcutaneous or intramusoular route and challenged after three weeks and the possibilities of protection was tested. Throughout the studies. the above mentioned vaccines possibly protected the vaccinated guinea pigs more than 80 per cent compared to that of the controls. This experimental results strongly suggest that the vaccine may possibly applicable to bovine.

• 대한임상검사과학회지
• /
• 제39권1호
• /
• pp.19-24
• /
• 2007

The aim of this study was to evaluate the bacterial effects of Moraxella catarrhalis in otitis media with effusion (OME) by photodynamic therapy (PDT). Bacterial suspensions (10000 CFU/mL) were prepared. The colony forming units (CFU) of Moraxella catarrhalis have been measured after an application of photogem plus 632 nm diode laser irradiation. One ml of the bacterial suspensions have been incubated in the dark for 3h with various concentrations of photogem ($0.625{\sim}5.0_{\mu}g/mL$) and then irradiated with 632 nm diode laser ($15J/cm^2$). After, the PDT Moraxella catarrhalis suspensions ($50{\mu}L$) were inoculated on chocolate agar plate and cultured in the dark at $37^{\circ}C$, 5% $CO_2$ condition for 18h. The colony forming units off the bacteria were measured. Also transmission electron microscopy (TEM) was employed to evaluate the effect of otitis media pathogens by PDT. The nucleus of Moraxella catarrhalis was stained using green fluorescent nucleic acid dye thiazole orange and the fluorescence intensity of the nucleus was measured by flow cytometry. The PDT was effective in killing Moraxella catarrhalis at the photogem dose of $5.0_{\mu}g/mL$, respectively, As assessed by flow cytometry analysis the fluorescence intensity of the nucleus got lower after PDT. TEM result appeared to able to cause damage to the bacterial membranes. On the basis of these findings, bacterial photodynamic therapy with photogem can be considered to be a promising new therapeutic approach for OME.

• Journal of Microbiology
• /
• 제40권2호
• /
• pp.119-124
• /
• 2002

Experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform used as a general indicator organism based on the chlorine residuals as a disinfectant. The water samples were taken from the outlet of a settling basin in a conventional surface water treat- ment system that is provided with the raw water drawn from the mid-stream of the Han River, The inactivation of total coliform was experimentally analysed for the dose of disinfectants contact time, filtration and mixing intensity. The curves obtained from a series of batch processes were shaped with a general tailing-off and biphasic mode of inactivation, i.e. a sharp loss of bacterial viability within 15 min followed by an extended phase. In order to observe the effect of carry-over suspended solids on chlorine consumption and disinfection efficiency, the water samples were filtered, prior to inoculation with coliforms, with membranes of both 2.5$\mu$m and 11.0 $\mu$m pore size, and with a sand tilter of 1.0 mm in effective size and of 1.4 in uniformity coefficient. As far as the disinfection efficiency is concerned, there were no significant differences. The parameters estimated by the models of Chick-Wat-son, Hom and Selleck from our experimental data obtained within 120 min are: log(N/N$\_$0/)=-0.16CT with n=1, leg(N/N$\_$0/)=-0.71C$\^$0.87/ with n 1 for the Chick-Watson model, log (N/N$\_$0/)=-1.87C$\^$0.47/ T$\^$0.36/ for the Hom model, log (MHo)=-2.13log (1+CT/0.11) for the Selleck model. It is notable that among the models reviewed with regard to the experimental data obtained, the Selleck model appeared to most closely resemble the total coliform survival curve.

• Environmental Engineering Research
• /
• 제16권4호
• /
• pp.243-252
• /
• 2011

Several mathematical relationships have been developed to describe bacterial responses to UV irradiation. Pseudomonas aeruginosa was taken as a bacterial model. The results obtained showed that the kinetics of disinfection is far to be as uniform. In fact, application of the model of Chick-Watson in its original form or modification, taking into account the speed change during the disinfection process, has not significantly improved results. The application of both models of Collins-Selleck and Hom constitute a major opportunity to simulate goodly the kinetics of UV disinfection. The results obtained showed that despite the major advantage held by applying the Hom model in this process of disinfection and for all strains studied, the model of Collins-Selleck gave the best results for the description of the UV inactivation process. The design of reactors, operating in continuous disinfection system, requires taking into account the hydrodynamic behaviour of water in the reactor. Knowing that a reduction of 4-log is necessary in the case of wastewater reuse for irrigation, a model integrating the expression of disinfection kinetics and the hydrodynamics through the UV irradiation room was proposed. The results highlight the interest to develop reactors in series working as four perfectly mixed reactors.

• 한국식품과학회지
• /
• 제33권2호
• /
• pp.226-230
• /
• 2001

좁쌀탁주를 초고압으로 처리하여 미생물 살균 및 효소불활성화의 효과를 측정하였다. 무처리 좁쌀탁주의 세균은 $6.8{\times}10^7\;CFU/mL$, 젖산균은 $1.3{\times}10^8\;CFU/mL$, 효모는 $8.4{\times}10^7\;CFU/mL$이었다. 좁쌀탁주를 상압에서 열처리($65^{\circ}C$/30분)하였을 때 젖산균과 효모는 완전히 사멸되었으나 세균은 $2.2{\times}10^5\;CFU/mL$ 잔존하였다. 좁쌀탁주를 초고압으로 처리한 결과 젖산균과 효모는 압력의 증가에 따라 급격히 감소하였으며, 400 MPa에서는 완전히 사멸되었다. 세균은 상온에서 압력을 600 MPa로 높여도 멸균되지 않았으며, 400 MPa/10분에서 처리온도의 증가에 따라 급격히 감소하는 경향을 보였으나, $66^{\circ}C$에서도 완전히 사멸되지 않았으며, $66^{\circ}C/400$ MPa에서 60분, 600 MPa에서 10분 처리로 완전히 사멸되었다. ${\alpha}-amylase$의 활성은 처리압력의 증가에 따라 감소하였으며, 상온/600 MPa/10분에서 73.2% 잔존한 반면, glucoamylase의 활성은 압력의 증가에 따라 상승하는 경향을 보였다. 400 MPa에서 처리온도의 증가에 따라 ${\alpha}-amylase$와 glucoamylase 모두 활성이 감소하였는데, $66^{\circ}C$에서 ${\alpha}-amylase$는 59.7%, glucoamylase는 20.5% 불활성화되었다. 가열처리($65^{\circ}C$, 30 분)에 의한 ${\alpha}-amylase$의 잔존활성은 14.1%이었는데 반하여, $66^{\circ}C/600\;MPa$에서 30분 처리로 잔존활성이 1.2% 이하가 되었다.