• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.167-178
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• 2023

Large amounts of waste and wastewater from aquaculture have negatively impacted ecosystems. Among them, shrimp aquaculture wastewater contains large amounts of nitrogen contaminants derived from feed residues in an aerobic environment. This study isolated candidate strains from adult rockworms to treat shrimp aquaculture wastewater (SAW) in an aerobic environment. Among 87 strains isolated, 25 grew well at the same temperature as the shrimp aquaculture with excellent polymer degradation ability (>0.5 cm clear zone). Six isolates (strains AL1, AL4, AL5, AL6, LA10, and PR15) were finally selected after combining strains with excellent polymer degradation ability without antagonism. 16S rRNA sequencing analysis revealed that strains AL1, AL4, AL5, AL6, LA10, and PR15 were closely related to Bacillus paramycoides, Bacillus pumilus, Stenotrophomonas rhizophila, Bacillus paranthracis, Bacillus paranthracis, and Micrococcus luteus, respectively. When these six isolates were applied to SAW, they reached a maximum cell viability of 2.06×10⁵ CFU mL^-1. Their chemical oxygen demand (COD_Cr) and total nitrogen(TN) removal rates for 12h were 51.0% and 44.6%, respectively, when the COD_Cr/TN ratio was approximately 10.0. Considering these removal rates achieved in this study under batch conditions, these six isolates could be used for aerobic denitrification. Consequently, these six isolates from rockworms are good candidates that can be applied to the field of aquaculture wastewater treatment.

• Journal of Environmental Science International
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• v.28 no.9
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• pp.719-727
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• 2019

In this study, the effect on the stability of Aerobic Granular Sludge (AGS) with different Carbon/Nitrogen (C/N) ratios was investigated. The C/N ratios were controlled to 10.0, 7.5, 5.0, and 2.5 using the sequencing batch reactor, and the results showed that the removal efficiency of organic matter and total nitrogen decreased simultaneously with the decrease of C/N ratio. The removal efficiency of organic matter and total nitrogen at C/N ratio of 2.5 was 70.7% and 52.3% respectively. In addition, the AGS/mixed liquor suspended solids (MLSS) ratio showed a tendency to decrease from 85.7% to 73.7%, while the sludge volume index showed a tendency to increase from 82 mL/g to 102 mL/g as the C/N ratio decreased. At the same time, the apparent deviation of polysaccharide (PS) content in extracellular polymeric substances was observed, and polysaccharides/protein (PS/PN) ratio decreased from 0.62 to 0.31 as the C/N ratio decreased. Optical microscope observations showed that the reduction in C/N ratio caused the growth of filamentous bacteria and significantly affected the stability of AGS.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.162-167
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• 2004

In this study, untreated (UT), water soaking (WT), and sanitizing solutions [chlorine at 100 ppm (CL): ethanol at 10% (ET); hydrogen peroxide at 1% (HP); chlorine at 100 ppm + ethanol at 10%(CE); chlorine at 100 ppm + hydrogen peroxide at 1% (CH); ethanol at 10% + hydrogen peroxide at 1% (EH); chlorine at 100 ppm + ethanol at 10% + hydrogen peroxide at 1% (CEH)] were compared in terms of their antimicrobial effectiveness against natural microflora of wild cabbage (Brassica oleracea var. capitata). All samples were kept in sanitizing solutions for 2 min, and effectiveness of sanitizing agents was evaluated based on number of decimal reduction of total aerobic mesophilic, total coliforms, E. coli, lactic acid bacteria, and yeast and mold counts. Average initial levels of these organisms in samples were $9.21{\pm}0.15,\;6.60{\pm}0.06,\;6.08{\pm}0.03,\;and\;3.66{\pm}0.08\;log_{10}\;CFU/g$ for total aerobic mesophilic bacteria, total coliforms, lactic acid bacteria, and yeasts and molds, respectively, Escherichia coli was not detected in any tested samples. Decimal reduction of populations of total aerobic mesophilic, total coliforms, E. coli, lactic acid bacteria, and yeasts and molds were: in $WT\;8.09,\;5.36,\;5.82,\;and\;3.57 log_{10}\;CFU/g;\;in \;CL\;7.39,\;4.10\;5.24,\;2.45\;log_{10}\;CFU/g;\;in\;ET\;6.78,\;4.23,\;5.20,\;2.50\;log_{10}\;CFU/g;\;in\;HP\;6.11,\;4.27,\;5.28,\;2.46\;log_{10}\;CFU/g;\;in\;CE\;6.18,\;4.26,\;5.31,\;2.49\;log_{10}\;CFU/g;\;in\;CH\;6.10,\;3.77,\;5.33,\;2.46\;log_{10}\;CFU/g;\;in\;EH\;6.07\;3.82,\;4.76,\;2.41\;log_{10}\;CFU/g;\;and\;in\;CEH\;5.27,\;3.45,\;4.45,\;2.15\;log_{10}\;CFU/g,$ respectively. Statistical analysis of the results showed effectiveness of CEH sanitizing solution for elimination of microbial contamination was the highest among all sanitizer treatments.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.468-476
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• 2020

We aimed to analyze the microbiological quality of the ready-to-eat (RTE) side dishes collected from traditional markets, supermarkets, and cafeterias in Gyeonggi-do in 2019. A total of 108 samples were analyzed for total aerobic bacterial counts, coliforms and foodborne pathogens depending on place of purchase and cooking methods. Results show that Bacillus cereus was detected in 14 (12.9%) out of 108 samples of side dishes, while no other foodborne pathogens were detected. The mean detected level (range) of total aerobic bacteria depending on place of purchase was 5.8 log CFU/g (3.0 to 8.2 log CFU/g) for traditional markets, 4.3 log CFU/g (2.4 to 7.8 log CFU/g) for supermarkets, and 3.80 log CFU/g (0.0 to 6.8 log CFU/g) for cafeterias, indicating that there was a significant (P<0.05) difference in total aerobic bacterial counts among places of purchase. Among the samples, the highest counts of total aerobic bacteria and coliforms were detected in saengchae (raw vegetables), followed by namul (seasoned herbs, vegetables), bokkeum (stir-fried foods), and jorim (foods cooked in soy sauce). The growth of total aerobic bacteria in seasoned soybean sprouts was inhibited when the sprouts were stored at 4℃ up to 24 h, whereas bacteria rapidly grew at 20 and 35℃ after 3 and 6 h, respectively. These results reveal that storage temperature might play a significant role for the microbiological quality of seasoned soybean sprouts when they are sold in markets. Thus, this study suggests that RTE side dishes should be stored at refrigerated temperature when being sold at markets as well as after purchasing to improve their microbiological quality.

• Environmental Engineering Research
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• v.12 no.4
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• pp.129-135
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• 2007

This study evaluated microbial risk that could develop within soil microbial communities after amended with organic fertilizers from stabilized swine manure waste. For this purpose, we assessed the occurrences and competitiveness of antibiotic resistance and pathogenicity in soil microbial communities that were amended with swine manure wastes stabilized by a traditional lagoon fermentation process and an autothermal thermophilic aerobic digestion process, respectively. According to laboratory cultivation detection analysis, soil applications of the stabilized organic fertilizers resulted in increases in absolute abundances of antibiotic resistant bacteria and of two tested pathogenic bacteria indicators. The increase in occurrences might be due to the overall growth of microbial communities by the supplement of nutrients from the fertilizers. Meanwhile, the soil applications were found to reduce competitiveness for various types of antibiotic resistant bacteria in the soil microbial communities, as indicated by the decrease in relative abundances (of total viable heterotrophic bacteria). However, competitiveness of pathogens in response to the fertilization was pathogens-specific, since the relative abundance of Staphylococcus was decreased by the soil applications, while the relative abundance of Salmonella was increased. Further testes revealed that no MAR (multiple antibiotic resistance) occurrence was detected among cultivated pathogen colonies. These findings suggest that microbial risk in the soil amended with the fertilizers may not be critical to public health. However, because of the increased occurrences of antibiotic resistance and pathogenicity resulted from the overall microbial growth by the nutrient supply from the fertilizers, potential microbial risk could not be completely ruled out in the organic-fertilized soil samples.

• Food Science of Animal Resources
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• v.30 no.1
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• pp.141-147
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• 2010

This study evaluated the antimicrobial effects of retort process and gamma irradiation on reduction of total bacterial populations in spicy chicken sauce, which is served on top of the steamed rice. Commercial spicy chicken sauce was treated with retort and gamma ray at 0, 1, 3, 5, and 10 kGy. Total aerobic bacterial populations were then enumerated on plate count agar and isolated bacteria from the test samples were identified using PCR analysis. Moreover, gamma ray sensitivity of identified bacteria was evaluated by $D_{10}$ values, and genotoxicity of gamma-irradiated samples was examined. Gamma irradiation at 3 kGy reduced total aerobic bacterial cell counts in spicy chicken sauce below detection limit, but total aerobic bacterial cell counts in test samples treated with retort were 2.1 log CFU/g. Identified bacteria from the samples were Bacillus subtilis, B. amyloiquefaciense, and B. pumils, and the $D_{10}$ values for B. subtilis and B. cereus were 0.39 ($R^2\;=\;0.921$) and 0.28 log CFU/g ($R^2\;=\;0.904$), respectively. The SOS chromotest showed that the gamma-irradiated spicy chicken sauce did not cause mutagenicity. These results indicate that gamma irradiation of spicy chicken sauce could be useful in ensuring microbial safety.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.3
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• pp.145-151
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• 2023

In order to extend shelf life for rockfish fillets by modified atmosphere packaging (MAP), different package atmospheres were compared in the product quality preservation. Firstly, CO₂ solubility was measured at 0, 5, 10, and 15℃ to be incorporated into the mathematical model to predict the volume and CO₂ concentration of the package at expected storage temperature. The CO₂ solubility given in Henry's constant decreased with temperature to be fitted with a linear equation. Then air packaging as control and four MAP conditions of 100 g fillets were prepared and stored for duration of 5 days at 10℃ to compare them in the quality preservation effect. Four MAP conditions employed were CO₂(60):O₂(30):N₂(10), CO₂(60):O₂(0):N₂(40), CO₂(30):O₂(30):N₂(40) andCO₂(30):O₂(0):N₂(70). MAP conditions with high CO₂ concentration inhibited total aerobic bacteria, and the conditions containing O₂ led to low TVB-N. MAP of CO₂(60):O₂(30):N₂(10) was found to be the best condition for rockfish fillet preservation considering total aerobic bacteria growth and nitrogenous volatiles production.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.399-408
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• 2012

The overall goal of this study was to characterize and quantify ammonia-oxidizing bacteria (AOB) in four different full-scale sequence batch reactor (SBR) wastewater treatment plants. Also, this study focused on assessing the occurrence of the alternative ammonia-oxidizing microbes such as anammox (anaerobic ammonia oxidation) bacteria (AMX) and ammonia-oxidizing archaea (AOA) in these systems. Based on total AOB numbers and the estimated cell density in the mixed liquor samples, AOB constituted 0.3 - 1.8% of the total bacterial population in the four WWTPs. Based on clone library, Nitrosomonas ureae-like AOB were dominant in plant A and B, while plant C and D had Nitrosomonas nitrosa-like AOB as major AOB group. The four different AMX primer sets targeting AMX 16S rRNA gene produced PCR amplicons distantly related to Chlamydia and Planctomycetales group bacteria. However, it was not clear these groups of bacteria perform anammox reaction in the SBR plants. Also, molecular evidence of AOA was found in one of the SBR plants, with a sequence located in the deep branch of the sediment creanarchaeota group.

• Food Science of Animal Resources
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• v.22 no.4
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• pp.316-321
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• 2002

Fresh ground pork was irradiated with the electron beam, and the microbiological and oxidative stability of ground pork was examined during refrigerated and frozen storage. During both storage, with the increase in the irradiation dose from 0 to 3.0 kGy, the inhibition effect of the growth of the total aerobic bacteria and the mesophiles also increased. Psychrotrophic bacteria were not detected at all in the whole experiment. On the other hand, electron beam irradiation promoted the oxidative rancidity of ground pork during refrigerated and frozen storage. The catalytic effect of oxidation was more pronounced with the electron beam dose of 3.0 than that of 1.5 kGy. As a result, the control of lipid oxidation must be achieved to fully utilize the sterilization effect of electron beam in the ground pork.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.657-663
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• 2002

Probiotics have been suggested to improve gastrointestinal health in humans. To investigate the effects of Bacillus polyfermenticus SCD administration on fecal microflora and putrefactive metabolites in humans, Bacillus polyfermenticus SCD (4.00${\times}$10$\sub$5/ CFU/mg) was administrated to ten healthy subjects (5 men and 5 women, average age 24 years) three times a day for 2 weeks. Fecal samples were collected before (1st and 2nd weeks, control), during (3rd and 4th weeks), and 2 weeks after the administration. The fo11owing microbial groups were evaluated in the feces: aerobic and anaerobic bacteria, Bacillus polyfermenticus SCD, Lactobacillus, Bifidobacterium, total lactic acid bacteria, Salmonella, Clostridium, Clostridium perfringens, Eubacterium, Staphylococcus, Coliform bacteria, Pseudomunas, and Yeast. Fecal concentrations of total aerobic bacteria (p<0.05, p<0.01, 3rd and 4th weeks), total lactic acid bacteria (p<0.01, 3rd, 4th and 5th weeks), and Bifidobacteria (p<0.05, 4th and 5th weeks) were significantly increased in all subjects, compared to the control, from the 3rd week after the administration of the products. Clostridium (p<0.01, 4th week), Clostridium perfringens (p<0.05, p<0.01, 3rd and 4th weeks), and coliform (p<0.01,5th week) were significantly reduced from the 3rd week of administration. No significant changes in the fecal concentrations of Pseudomonas, Lactobacillus, Eubacterium, Staphylococcus, yeast, and total anaerobes were observed. Six weeks after the administration, the concentration of all rnicroorganlsrns returned to the basal level. Bacillus polyfermenticus SCD was significantly maintained from the 3rd week to 6th week of the study. Despite the absence of a statistical significance, the putrefactive metabolites (ammonia, indole, skatole, and $\rho$-cresol) and the pH value tended to be lower during and after the test periods than the base line. These results show that this probiotic preparation is able to colonize the intestine, and suggest that it may be useful as a beneficial probiotic in humans.