• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.221-227
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• 2011

Applications of green manures generally improve the soil quality in rice paddy in part through restructuring of soil microbial communities. To determine how different green manures affect soil microbial communities during the early stages of rice growth, fatty acid methyl ester (FAME) profiles were used to the effects of different management practices: 1) conventional farming (CF), 2) no-treatment (NT), 3) Chinese milk vetch (CMV), 4) green barley (GB), and 5) triticale in paddy field. With applications of green manures, soil organic matter was significantly higher than CF, while soil Na concentration was significantly lower compared with CF (p<0.05). Total soil microbial biomass of CMV was higher (p<0.05) than NF by approximately 31%. The highest ratio of monounsaturated fatty acid to saturated fatty acid was found in the GB plot, followed by CMV and triticale compared with CF (p<0.05), possibly indicating that microbial stress was less in GB and CMV plots. Populations of Gram-negative bacteria and arbuscular mycorrhizal fungi also were significantly higher green manures than CF (p<0.05). Our findings suggest that GB should be considered as optimum green manure for enhancing soil microbial community at an early growing stage in paddy field.

• Korean journal of applied entomology
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• v.52 no.1
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• pp.35-43
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• 2013

All tested Korean populations of the diamondback moth, Plutella xylostella, are known to be resistant especially against pyrethroid insecticides by mutation in its molecular target, para-sodium channel. Moreover, P. xylostella is able to develop resistance against most commercial insecticides. This study was performed to develop an efficient control technique against P. xylostella by a combined treatment of an endoparasitoid wasp, Cotesia plutellae, and a microbial insecticide, Bacillus thuringiensis. To investigate any parasitism preference of C. plutellae against susceptible and resistant P. xylostella, five different populations of P. xylostella were compared in insecticide susceptibilities and parasitism by C. plutellae. These five P. xylostella populations showed a significant variation against three commercial insecticides including pyrethroid, organophosphate, neonicotinoid, and insect growth regulator. However, there were no significant differences among five P. xylostella populations in their parasitic rates by C. plutellae. Moreover, parasitized larvae of P. xylostella showed significantly higher susceptibility to B. thuringiensis. As an immunosuppressive agent, viral ankyrin genes (vankyrins) encoded in C. plutellae were transiently expressed in nonparasitized larvae. Expression of vankyrins significantly enhanced the efficacy of B. thuringiensis against the third instar larvae of P. xylostella. Thus an immunosuppression induced by C. plutellae enhanced the insecticidal efficacy of B. thuringiensis. These results suggest that a combined treatment of C. plutellae and B. thuringiensis may effectively control the insecticide-resistant populations of P. xylostella.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.1
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• pp.123-127
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• 2011

This study was conducted to decrease the microbial hazard in kimchi saline water with microwave plasma sterilization system and to evaluate the inactivation of foodborne pathogens by the microwave plasma sterilization system as a non-thermal treatment. Contamination of coliform, Escherichia coli, and yeasts and molds were detected in the used saline water, and the microbial populations increased as the saline water was reused repeatedly. The $D_{10}$-values of E. coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes by the microwave plasma sterilization system were 0.48, 0.52, and 0.45 cycle, respectively. In addition, the microbial populations of coliform, E. coli, Salmonella spp., total aerobic bacteria, and yeasts and molds in the used kimchi saline water were significantly decreased by treating the saline water using the microwave plasma sterilization system. Therefore, these results suggest that microwave plasma sterilization system can be useful in improving the microbial safety of the used saline water.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.270-279
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• 2014

Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g $VS_{removal}$. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.661-672
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• 1998

Two experiments were conducted to examine the effects of a range of concentrations of ruminal fluid ammonia ($NH_3$-N) on forage digestibility, microbial growth efficiency and the mix of microbial species. Urea was either continuously infused directly into the rumen of sheep fed 33.3 glh of oaten chaff (Exp. I) or sprayed onto the oaten chaff (750 g/d) given once daily (Exp. 2). Concentrations of $NH_3$-N increased with incremental addition of urea (p < 0.01). Volatile fatty acids (VFA) concentrations and 24 h in sacco organic matter digestibility in the rumen were higher when supplemental urea was given (p < 0.01). The (C2 + C4) : C3 VFA ratio was lower (p < 0.05) when $NH_3$-N was above 200 mgN/I. The fungal sporangia appearing on oat leaf blades were significantly higher when urea was supplemented, indicating that $NH_3$-N was a growthlimiting nutrient for fungi at levels of $NH_3$-N below 30 mgN/l. The density of protozoa was highest when $NH_3$-N concentrations were adjusted to 30 mgN/I for continuously fed ($4.4{\times}10^5/ml$) and to 168 mgN/1 for once daily feeding ($2.9{\times}10^5/ml$). Thereafter increasing concentrations of $NH_3$-N, were associated with a concomitant decline in protozoal densities. At the concentration of $NH_3$-N above 200 mgN/l, the density of protozoa was similar to the density of protozoa in ruminal fluid of the control sheep ($1.8{\times}10^5/ml$). The efficiency of net microbial protein synthesis in the rumen calculated from purine excretion was 17-47% higher when the level of $NH_3$-N was above 200 mgN/1. The possibilities are that 1) there is less bacterial cell lysis in the rumen because of the concomitant decrease in the protozoal pool and/or 2) microbial growth per se in the rumen is more efficient with increasing $NH_3$-N concentrations.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.1
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• pp.27-31
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• 1990

Influences of plant phenolic acids and their possible metabolites(non-phenolic aromatic acids involved) in the rumen on the cellulolytic activity of mixed rumen populations were examined by a simple in vitro culture technique. Initial concentrations of aromatic acids were 1, 5, 10 and 20 mM/l. All the tested aromatic acids reduced microbial cellulose digestion especially at the higher initial concentration. P-Coumaric acid, ferulic acid and cinnamic acid, those having unhydrogenated propenoic side chain were more inhibitory than were 3-phenylpropinic acid and phloretic acid, those having hydrogenated propanoic side chain. Lag-time for cellulose digestion was prolonged by former three acids by 16 h. Apparent reduction in p-coumaric acid concentration was observed at 24 h when cellulose digestion began. Volatile fatty acid productions from cellulose fermentation were shifted by former three aromatic acids to produce more acetate and less propionate. This suggests that the selection of celluloytic organisms was induced by these aromatic acids.

• Journal of Microbiology
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• v.42 no.1
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• pp.1-8
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• 2004

Changes in the bacterial populations of a 5-stage biological nutrient removal (BNR) process, with a step feed system for wastewater treatment, were monitored by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA fragments. DGGE analysis indicated seasonal community changes were observed, however, community profiles of the total bacteria of each reactor showed only minor differences in the samples obtained from the same season. The number of major bands was higher in the summer samples, and decreased during the winter period, indicating that the microbial community structure became simpler at low temperatures. Since the nitrogen and phosphate removal efficiencies were highly maintained throughout the winter operation period, the bacteria which still remaining in the winter sample can be considered important, playing a key role in the present 5-stage BNR sludge. The prominent DGGE bands were excised, and sequenced to gain insight into the identities of the predominant bacterial populations present, and most were found to not be closely related to previously characterized bacteria. These data suggest the importance of culture-independent methods for the quality control of wastewater treatment.

• Journal of Environmental Science International
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• v.23 no.8
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• pp.1429-1436
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• 2014

In this study, we investigated the effects of dietary supplementation (n = 40 pigs/treatment) with bamboo powder (0, 1, 2 and 3%) for 38 days. We evaluated growth performance, blood metabolites, and carcass characteristics of fattening pigs and gas emission and microbial populations in pig manure, to obtain data on pork producers for environmental management. We obtained the following results. First, supplementation with increasing amounts of bamboo powder had a significant (P < 0.05) effect on feed intake, feed efficiency, and glucose contents (except for initial and final body weight, weight gain, carcass characteristics, and blood urea nitrogen). In terms of blood metabolites, glucose and blood urea nitrogen tended to decrease with increasing amounts of bamboo powder. Second, the amounts of ammonia, methane, amine, hydrogen sulfide, and acetic acid were reduced by increasing amounts of bamboo powder when compared with the controls (P < 0.05). However, there were no significant differences in pH, propionic acid, iso-butyric acid, butyric acid, iso-valeric acid, and valeric acid among all treatments. The lowest gas emission was observed when 3% bamboo powder was used. Third, supplementation with increasing amounts of bamboo powder tended (P < 0.05) to increase the total number of bacteria, Lactobacillus spp., and yeast, but E. coli, Salmonella spp., and Shigella spp. were not detected in any treatment. In conclusion, the results of this study suggest that supplementation with bamboo powder was effective in reducing gas emission and inhibiting pathogen populations in pig manure by lowering the pH of the manure.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.1
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• pp.71-79
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• 2018

Objective: Gelidium amansii (Lamouroux) is a red alga belonging to the family Gelidaceae and is commonly found in the shallow coasts of many East Asian countries, including Korea, China, and Japan. G. amansii has traditionally been utilized as an edible alga, and has various biological activities. The objective of this study was to determine whether dietary supplementation of G. amansii could be useful for improving ruminal fermentation. Methods: As assessed by in vitro fermentation parameters such as pH, total gas, volatile fatty acid (VFA) production, gas profile (methane, carbon dioxide, hydrogen, and ammonia), and microbial growth rate was compared to a basal diet with timothy hay. Cannulated Holstein cows were used as rumen fluid donors and 15 mL rumen fluid: buffer (1:2) was incubated for up to 72 h with four treatments with three replicates. The treatments were: control (timothy only), basal diet with 1% G. amansii extract, basal diet with 3% G. amansii extract, and basal diet with 5% G. amansii extract. Results: Overall, the results of our study indicate that G. amansii supplementation is potentially useful for improving ruminant growth performance, via increased total gas and VFA production, but does come with some undesirable effects, such as increasing pH, ammonia concentration, and methane production. In particular, real-time polymerase chain reaction indicated that the methanogenic archaea and Fibrobacter succinogenes populations were significantly reduced, while the Ruminococcus flavefaciens populations were significantly increased at 24 h, when supplemented with G. amansii extracts as compared with controls. Conclusion: More research is required to elucidate what G. amansii supplementation can do to improve growth performance, and its effect on methane production in ruminants.

• Preventive Nutrition and Food Science
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• v.11 no.4
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• pp.344-347
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• 2006

This study evaluated the use of electron beam irradiation for decontamination of the Korean medicinal herb, Angelica gigas Nakai. Herb samples were irradiated at doses of 2, 8, and 16 kGy, respectively. Populations of microorganisms in Angelica gigas Nakai decreased by 2$\sim$3 log cycles at 8 kGy irradiation. Electron beam irradiation caused negligible changes in Hunter color L, a, and b values. Sensory evaluations of Angelica gigas Nakai confirmed that irradiation caused no significant changes in the organoleptic properties of the samples. These results suggest that electron beam-irradiated herbs retain a better microbial safety and sensory qualities, compared with the non-irradiated.