The rapid development of biotechnology has increased the importance of microorganisms or their genetic information. Thus, the Nagoya Protocol on access to genetic resources and the fair and equitable sharing of benefits arising from their utilization was established, and countries are working to secure industrially and academically useful bioresources to deal with the agreement. In the case of Korea, because 67% of bioresources are imported from abroad, we are required to secure domestic bioresources as well. The number of isolated foodborne illness-causing microorganisms is predicted to invrease based on the incresing number of outbreaks of foodborne illness each year. Consequently, appropriate long-term preservation methods are necessary to secure the isolated microorganisms for the purpose of research and resourcification. Therefore, the long-term preservation methods for bacteria, fungi, viruses, and protozoa were investigated in this study, from domestic and international bioresource banks, and the functions of the cryoprotectants were reviewed and discussed. This review should be informative in the preservation of microorganisms and contribute to the development of biotechnology.

The present study investigated effects of microbial additives and silo density on chemical compositions, fermentation indices, and aerobic stability of whole crop rice (WCR) silage. The WCR (“Youngwoo”) was harvested at 49.7% dry matter (DM), and ensiled into 500 kg bale silo with two different compaction pressures at 430 kgf (kilogram-force)/cm2 (LOW) and 760 kgf/cm2 (HIGH) densities. All WCR forage were applied distilled water (CON) or mixed inoculants (Lactobacillus brevis 5M2 and Lactobacillus buchneri 6M1) with 1:1 ratio at 1x105 colony forming unit/g (INO). The concentrations of DM, crude protein, ether extract, crude ash, neutral detergent fiber, and acid detergent fiber of whole crop rice before ensiling were 49.7, 9.59, 2.85, 6.74, 39.7, and 21.9%, respectively. Microbial additives and silo density did not affect the chemical compositions of WCR silage (p>0.05). The INO silages had lower lactate (p<0.001), but higher propionate (p<0.001). The LOW silages had higher lactate (p=0.004). The INO silages had higher yeast count (p<0.001) and aerobic stability (p<0.001). However, microbial counts and aerobic stability were not affected by silo density. Therefore, this study concluded that fermentation quality of WCR silage improved by microbial additives, but no effects by silo density.

Recently, the purchase of fresh-cut produce and meal kits has increased. Ready-to-eat (RTE) fresh-cut products have potentially hazard of cross-contamination of various microorganisms in the processes of peeling, slicing, dicing, and shredding. There are frequent cases of protozoa food poisoning, such as Cyclospora and Cryptosporidium, caused by fresh-cut products. The objective of the study is to investigate the microbiological qualities of various types of RTE fresh-cut products in the domestic on/offline markets. RTE fresh-cut fruits cup (n=100), fresh-cut vegetables (n=50), and vegetables in meal kits (Vietnamese spring rolls and white radish rolls kits, n=50) were seasonally analyzed. The contamination levels of hygienic indicator organisms, yeast and mold (YM), and foodborne pathogens (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7) were monitored. Overall, the lowest microbiological qualities of meal kits vegetables were observed, followed by RTE fresh-cut fruits cup and fresh-cut vegetables. Contamination levels of total aerobic bacteria, coliforms, and YM in meal kits vegetables were 5.91, 3.90, and 4.71 logs CFU/g, respectively. From the qualitative analysis, 6 out of 200 RTE fresh-cut products (3%) returned positive result for S. aureus. From the quantitative analysis, the contamination levels of S. aureus in purple cabbage from a meal-kit and fresh-cut pineapple were below the acceptable limit (100 CFU/g). Staphylococcus enterotoxin seg and sei genes were detected in RTE fresh-cut celery and red cabbage from meal-kits, respectively. S. aureus contamination must be carefully controlled during the manufacturing processes of RTE fresh-cut products. Neither Cyclospora cayetanensis nor Cryptosporidium parvum was detected in the samples of RTE fresh-cut products and vegetables from meal-kits from the Korean retail markets.

The present study was performed to investigate the effects of NH3-N and nitrifying microorganisms on the increased BOD of downstream of the Yeongsan river in Gwangju. Water samples were collected periodically from the 13 sampling sites of rivers from April to October 2021 to monitor water qualities. In addition, the trends of nitrogenous biochemical oxygen demand (NBOD) and microbial clusters were analyzed by adding different NH3-N concentrations to the water samples. The monitoring results showed that NH3-N concentration in the Yeongsan river was 22 times increased after the inflow of discharged water from the Gwangju 1st public sewage treatment plant (G-1-PSTP). Increased NH3-N elevated NBOD levels through the nitrification process in the river, consequently, it would attribute to the increase of BOD in the Yeongsan river. Meanwhile, there was no proportional relation between NBOD and NH3-N concentrations. However, there was a significant difference in NBOD occurrence by sampling sites. Specifically, when 5 mg/L NH3-N was added, NBOD of the river sample showed 2-4 times higher values after the inflow of discharged water from G-1-PSTP. Therefore, it could be thought other factors such as microorganisms influence the elevated NBOD levels. Through next-generation sequencing analysis, nitrifying microorganisms such as Nitrosomonas, Nitroga, and Nitrospira (Genus) were detected in rivers samples, especially, the proportion of them was the highest in river samples after the inflow of discharged water from G-1-PSTP. These results indicated the effects of nitrifying microorganisms and NH3-N concentrations as important limiting factors on the increased NBOD levels in the rivers. Taken together, comprehensive strategies are needed not only to reduce the NH3-N concentration of discharged water but also to control discharged nitrifying microorganisms to effectively reduce the NBOD levels in the downstream of the Yeongsan river where discharged water from G-1-PSTP flows.

Microbiologically Influenced Corrosion (MIC) occurring in underground buried pipes of API 5L X65 steel was investigated. MIC is a corrosion phenomenon caused by microorganisms in soil; it affects steel materials in wet atmosphere. The microstructure and mechanical properties resulting from MIC were analyzed by OM, SEM/EDS, and mapping. Corrosion of pipe cross section was composed of ① surface film, ② iron oxide, and ③ surface/internal microbial corrosive by-product similar to surface corrosion pattern. The surface film is an area where concentrations of C/O components are on average 65 %/ 16 %; the main components of Fe Oxide were measured and found to be 48Fe-42O. The MIC area is divided into surface and inner areas, where high concentrations of N of 6 %/5 % are detected, respectively, in addition to the C/O component. The high concentration of C/O components observed on pipe surfaces and cross sections is considered to be MIC due to the various bacteria present. It is assumed that this is related to the heat-shrinkable sheet, which is a corrosion-resistant coating layer that becomes the MIC by-product component. The MIC generated on the pipe surface and cross section is inferred to have a high concentration of N components. High concentrations of N components occur frequently on surface and inner regions; these regions were investigated and Na/Mg/Ca basic substances were found to have accumulated as well. Therefore, it is presumed that the corrosion of buried pipes is due to the MIC of the NRB (nitrate reducing bacteria) reaction in the soil.

본 연구는 다양한 상대습도(11~93%) 조건에서 해조류의 미생물 안정성 및 품질특성에 미치는 영향을 조사하였다. 미생물 안정성은 저장 중 대장균군, 일반세균, 효모 및 곰팡이수를 분석하였다. 일반세균은 상대습도 69~93%에서 4.40~7.00 log CFU/g, 효모 및 곰팡이는 4.20~6.40 log CFU/g로 상대습도 69%이상 조건에서 일반세균, 효모 및 곰팡이의 수가 급격하게 증가하였다. 고결현상은 상대습도 11~53% 조건에서는 일어나지 않았으나 69, 81, 93% 조건에서는 각각 86.9, 99.45, 99.98%로 높은 고결현상을 가지는 것으로 나타났다. 색도는 상대습도가 높아질수록 L값과 b값이 감소하였고, a값이 증가하여 갈변현상이 일어났다. 또한, 총 페놀함량(9.10~8.66 mg GAE/100 g dw), ABTS 소거능(24.20~24.18 mg AAE/100 g dw), FRAP(15.34~15.33 mg Fe(II)/100 g dw)활성은 저장 중 상대습도 11~33%에서 가장 높게 유지되었다. 그러나, 상대습도 43~93%에서 저장 중 총 페놀함량(8.66~4.00 mg GAE/100 g dw), ABTS(22.57~4.50 mg AAE/100 g dw), FRAP(13.06~4.00 mg AAE/100 g dw)활성이 감소하는 것으로 나타났다. 상대습도 81% 조건에서 ABTS 및 FRAP이 1/3배로 감소하였고, 93% 조건에서 총 페놀함량, ABTS 및 FRAP이 각각 1/2배, 1/5배, 1/3배로 감소하였다. 따라서, 일반세균, 효모 및 곰팡이의 성장 억제, 고결현상 방지, 갈변억제, 높은 총 페놀함량과 항산화활성 유지를 위해서는 상대습도 53% 이하의 조건에서 보관하는 것이 미생물 안정성 및 품질특성 유지에 효과적일 것으로 판단된다.

This study investigated the minimum salt concentration required for achieving the optimal quality characteristics of sauerkrauts made by adding 0.5, 1.0, 1.5, 2.0, and 2.5% (w/w) of sea salt to cabbage according to the fermentation period. For evaluating the quality characteristics, we measured the microorganisms (lactic acid bacteria, yeast, and coliform group), pH, total acidity, salinity, chromaticity, and hardness every 24 hours. The lactic acid bacteria were identified and analyzed, and acceptance test was carried out on the 4th day of fermentation. The results showed that the salinity of 0.5, 1.0, 1.5, and 2.0% sauerkrauts on the 4th day of fermentation was lower than the average salinity of Baechu-Kimchi. The 0.5, 1.0, 1.5, and 2.0% sauerkrauts had significantly higher lactic acid bacteria than the 2.5% sample, and the coliform group was not detected after the 5th day of fermentation. Among the microbes identified, Weissella cibaria JCM 12495 was found only in domestic sauerkraut, in addition to Lactococcus lactis NCDO 604, Leuconostoc citreum JCM 9698, and Lactobacillus sakei DSM 20017. The results of the acceptance test show that 1.0 and 1.5% sea salt sauerkraut had significantly higher overall acceptance compared to the other samples. In conclusion, sauerkraut with a salt concentration of 1.0 and 1.5% (w/w) had abundant lactic acid bacteria and excellent sensory properties, suggesting that the production of low-salted sauerkraut can be adopted to reduce consumer salt intake in the future.

This study assessed the levels of water qualities and microbials contamination of inland olive flounder farms in Jeju in the summers from 2015 to 2017. Three farms (A-C) located in a concentrated area using mixing coastal seawater and underground seawater and one farm (D) located in an independent area using only coastal seawater were selected. Total ammonia nitrogen (TAN) reached a maximum of 0.898 ± 1.024 mg/L as N in the coastal seawater of A-C, which was close to the limit of the water quality management goal of the fish farm. TAN in the influent from A-C was up to three times higher than that of D, so that the discharged water did not spread to a wide range area along the coast and continued to affect the influent. TAN of the effluent in A-C increased by 2.7-4.6 times compared to the influent, resulting in serious self-pollution in the flounder farm. Heterotrophic marine bacteria in the influent of A-C was about 600 times higher than D, and the discharge of A-C was increased by about 30 times compared to the influent.

Application of the membrane process to wastewater treatment and reuse has been increasing due to water shortage, water pollution and an increase in water demand. Membrane fouling including biofouling should be controlled to extend its application. In this study, modulation of diffusible signal factor (DSF) system, the quorum sensing (QS) system that regulates EPS formation by microorganisms, was considered as a promising option to manage biofouling. Among many DSF compounds, cis -2-Decenoic acids (CDA) was selected. The experimental results showed that, as the CDA concentration increased, the density and number of stained cells decreased. The lowest density was observed when the CDA concentration of 300 nM was applied. The EPS on membrane surface decreased with increasing concentration of CDA. The CDA dosing also affected the EPS composition. At the 300 nM CDA dose, the total EPS reduced by up to 57% and the protein fraction by 35%. This study revealed the biofilm reduction effect of CDA under various conditions for MBR sludge. The application of CDA can be adapted to control biofouling in the MBR process.

세균은 분리막, 식품 포장 필름 및 바이오 의료 기기와 같은 다양한 미생물 막의 표면 위에서 자란다. 미생물 막 의 성장은 엑소폴리사카라이드의 복잡한 구조 형성과 밀접한 관련이 있다. 미생물 막이 항균제의 대량 수송의 어려움으로 성 장하게 될 경우 항균효과는 급격하게 감소한다. 항균 활동을 활성화하기 위해서 막의 표면은 살균 특성이 있는 기능성 물질 들로 변형, 코팅 또는 고정한다. 한 가지 아이디어는 막 표면에 양전하 이온을 도입하는 것이다. 양전하 이온인 4차 암모늄 그룹의 존재는 마그네슘이나 칼슘같이 세균 세포벽에 존재하는 2가 금속이온을 대체할 수 있다. 세포막 파괴의 효능은 표면 환경에서 사용 가능한 작용제들의 이동성에 달려있다. 이 리뷰에서는 4차 암모늄 그룹, 헬라민(helamine), 쌍성이온(zwitter ion)과 같이 여러 살생물제를 포함하고 있는 막들을 다룬다.

This study investigated the effect of bactocease, as a natural preservative, on the microbial growth and quality of fried fish paste during storage. To select the optimal concentration of bactocease, the inhibition effect of its different treatment concentrations (0.2, 0.4, and 0.8%) on total aerobic bacteria in fish paste dough during 5 days of storage was examined. The sample treated with 0.4% bactocease showed a 1.21 log reduction in microorganisms compared with that of the control. This result was higher than that with 0.2% bactocease and potassium sorbate and similar to that with 0.8% bactocease. Consequently, 0.4% bactocease was chosen as the best concentration for preparing the fried fish paste. Microbial growth on fried samples treated with preservatives was more inhibited by adding preservatives regardless of their type than that of the control after 15 days of storage. In addition, there were no significant differences in the quality between the samples treated with 0.4% bactocease and 0.2% potassium sorbate, such as volatile basic nitrogen contents, TBARS values, pH, and acidity. Therefore, these results indicate that food preservatives should be added into fried fish paste for controlling microbial growth, and bactocease can have a high potential to replace potassium sorbate in processed marine foods, including fried fish paste.

A laboratory-scale experiment was conducted to evaluate the effect of supplementing commonly used effective microorganisms on the chemical properties of swine liquid manure. Effective microorganisms used in this study were Bacillus subtilis (1.3×109 colony-forming unit (CFU)/ml), Enterococcus faecium (1.9×1010 CFU/ml), Aspergillus oryzae (2.0×109 CFU/ml), Saccharomyces cerevisiae (6.4×109 CFU/ml), Rhodobacter sphaeroides (1.2×108 CFU/ml), and Streptomyces griseus (6.2×108 CFU/ml). Swine liquid manure collected and decanted from a swine farm was used in this study. Treatments included control (distilled water supplementation), Treatment 1 (T1) (mixed microbes, 109 CFU/ml), and Treatment 2 (T2) (mixed microbes, 107 CFU/ml). Microbial mix was supplemented every 3.5 days and aerated six times (15 min each) a day to facilitate compositing. Ten ml of sample was collected at 2-, 4-, 6-, and 7-week intervals for the measurement of pH, ammonia-N, volatile fatty acid (VFA), total nitrogen, total phosphorus, and total potassium. At seven weeks, samples were further collected to analyze biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Ammonia-N was significantly (p<0.05) decreased in T1 and T2 by 36% and 30%, respectively, compared with control (23%). VFAs including butyrate, iso-butyrate, valerate, iso-valerate, and caproate were not detected in T1 from the four-week aerated sample. The BOD and COD were significantly (p<0.05) decreased in T1 by 96% and 58%, respectively. In conclusion, ammonia-N, VFA, BOD, and COD, known as odor indicators, were decreased in T1 and T2 compared with control, suggesting that effective microorganisms are useful for compositing swine liquid manure

달래의 전처리 방법을 통해 미생물 저감과 품질 유지 효과를 알아보기 위해 물리적인 처리로는 손 세척 1분, 버블 세척, Ultrasonication 처리를 50oC와 60oC의 온도에서 각각 1분, 3분, 5분 동안 세척하였고, 화학적 처리에서는 유기산인 푸마르산과 아세트산 용액 1.5%와 2% 농도에서 각각 1분, 3분, 5분 동안 침지 처리하였다. 미생물과 품질 분석 결과 물리적 처리에서는 버블 세척 3분이 곰팡이 저감에 효과적이었으나 일반세균 저감 효과는 적었고, Ultrasonication 60oC, 5분 처리에서 미생물 저감 효과가 가장 높았으나 색도의 a값이 증가하는 경향을 보여 녹색이 약해졌다. 화학적 처리에서는 acetic acid에 비해서 fumaric acid에서 일반세균과 곰팡이의 저감 효과가 높았으며, fumaric acid 1.5% 용액에서 3분 처리의 저감효과가 가장 높았다. 달래의 미생물 저감 효과가 좋은 버블세척 3분 (B3), fumaric acid 1.5%, 3분 처리(F153), 두 가지 방법을 조합한 병합(BF) 처리를 실시하고 9일 동안 4oC에서 저장하며 품질 특성을 비교해 본 결과, 일반세균보다는 곰팡이 저감에 더 효과적이었으며, 일반세균은 BF가 곰팡이는 F153에서 미생물 감소 효과가 있었다. 색변화에 있어 BF 처리의 ΔE값이 가장 낮았으며, 유기산 처리에서 색변화를 보여 F153에서 녹색이 약해졌다. 최대응집력 변화 알뿌리 보다는 녹색 줄기에서 현격히 나타났는데 저장 9일 차에 F153처리에서 녹색 줄기의 경도가 가장 높게 유지되었고 (P<0.05), 알뿌리 부분은 물리적 방법인 버블 세척 시 6일 차부터 다른 처리에 비해 낮아졌다(P<0.05). 달래의 미생물 저감과 품질의 유지를 고려할 때 전처리 방법으로는 fumaric acid 1.5%용액으로 3분 처리 시 미생물 저감 효과와 색·최대응집력의 특성 유지가 우수하였고, 3일 이내 의 유통기간이라면 병합 처리도 효과적인 방법으로 적용 할 수 있음을 알 수 있었다.

본 연구에서는 한국 전통 과자인 유과와 강정을 원·부재료와 기기 및 도구, 작업자의 개인위생, 제조공정별 원료에 대한 미생물학적 오염을 분석하였다. 유과제조 과정 중 현장에서 사용하고 있는 세척 방법과 횟수에 따른 미생물 저감효과를 확인하고자 하였다. 강정의 제조 공정 중 튀밥에서 일반세균수 1.2 Log CFU/g, 완제품의 경우 3.7 Log CFU/g까지 점차 증가하였다. 유과의 제조 공정 중 일반세균수는 불림공정에서 일반세균 최대 6.5 Log CFU/g 수준으로 증가하다가 튀김공정에서 1.3 Log CFU/g수준으로 감소하였으나 완제품에서 4.0 Log CFU/g 수준으로 재오염되는 것으로 확인되었다. 이는 제조과정 중에 작업도구와 기기 또는 작업자 등에 의한 교차오염으로 판단되었다. 작업 도구인 주걱의 경우 일반세균 약 4.4 Log CFU/g, 대장균군 4.2 Log CFU/g으로 매우 오염도가 나타났다. 유과의 불림단계에서 7일동안 일반세균 수가 최대 10 Log CFU/g 이상, 대장균군의 경우 6.8 Log CFU/g으로 증가하였다. 손 또는 도구를 이용한 세척 방법과 흐르는 물에 세 척한 방법을 비교하였을 때, 손을 이용하여 수돗물로 10 회 세척하였을 때 일반세균 5.0 Log CFU/g, 대장균군 2.8 Log CFU/g 감소한 것으로 확인되었다. 이상의 결과로 볼 때, 소규모 업체의 전통 한과 제조 시 작업자나 작업 도 구 및 기기 사용 후 세척 및 소독하는 과정이 요구되며 완제품의 미생물 오염도를 감소시키기 위해 현장에 적용할 수 있는 저감화 방법이 필요한 것으로 판단되었다.

본 연구는 로메인 상추에서 병원성미생물이 생존과 생육의 특성을 분석하여 안전관리 정보를 확보하고자 실시하였다. 로메인 상추에서 분무 접종한 E. coli O157:H7은 72시간 배양 후 초기균수 보다 2.0 log CFU/g 수준으로 증가하여 생존 및 증식이 가능한 것으로 판단되었다. 상추 잎의 상처 유무에 따른 E. coli O157:H7은 배양 72시 간 후 유의적 차이가 없었다. 상추 잎에 인위적인 상처에 내어 E. coli O157:H7을 접종하고 병원균의 분포를 조사한 결과 상처가 없는 상추는 표면이 매끄러워 균이 부착하지 못하거나 균수가 매우 낮았고, 상처가 있는 상추 잎은 거친 표면에 균이 밀집되어 상처를 통해 상추 내부로 침입하는 것으로 판단되었다. 병원성미생물의 상추 추출물 이용 여부는 10-100% 농도에서 배양 24시간 이후에 E. coli O157:H7 8.9 log CFU/mL, L. monocytogenes 8.6 log CFU/mL, P. carotovorum 8.8 log CFU/mL로 나타났다. 이는 병원성미생물과 식물병원균이 유사한 4 log CFU/g 이상의 증가율을 나 타내어 미생물이 상추 추출물을 영양원으로 사용할 수 있는 것으로 판단되었다. 상추 추출물 0.1%에서 초기 접종 농 도와 비교하여 E. coli O157:H7 2.7, L. monocytogenes 1.3, P. carotovorum 2.9 log CFU/mL 수준으로 증가하였다. 이에 따라 병원성 미생물의 최소생육농도는 0.1%보다 낮은 것으로 판단되었고, 상처를 통해 지속적으로 0.1% 수준의 상추 추출물이 병원성미생물에 제공되면 상추 내부에서도 생존 및 증식이 가능할 것으로 확인하였다.

본 연구는 생분해성 용기 개발의 연구성이 대두됨에 따 라서 동물성 재료로 제조한 생분해성 용기의 개발의 목적에 있다. 연구 결과 돈피, 우피, 닭피에 있어서 돈피가 우수한 수율과 단백질 분자량을 가진 것으로 나타났다. 이에 돈피를 이용하여 생분해 용기를 개발하였으며, 단면적 확인 결과 호두 껍질 분말 10%를 첨가한 처리구에서 적은 공극을 보였으며, 호두 껍질 분말 20%를 첨가한 처리구에서 공극의 크기가 큰 것을 확인할 수 있었다. 물성 연구 결과 호두 껍질 분말 10% 처리구가 더 높은 경도를 나타 내었으며, 호두 껍질 분말 20% 처리구가 더 높은 탄력성을 나타내었다. 압축강도는 호두 껍질 분말 20% 처리구가 더 높은 값을 나타내었다. General bacteria, E. coli 연구 결과 모든 일자에서 불검출되어 미생물로부터의 안정성은 더 장기간으로 실험해볼 필요가 있을 것으로 보인다. 또한 높은 항균 능력과 생분해능의 결과를 보여 저장 기간의 안정성이 높은 용기의 개발과 환경의 영향을 최소화 할 수 있을 것으로 판단된다. 따라서 돈피 젤라틴에 난각과 호두 껍질 분말을 넣어 제조한 생분해성 용기의 개발의 기초 데이터로 이용될 수 있을 것으로 생각된다.