• 한국유기농업학회지
• /
• 제20권4호
• /
• pp.687-702
• /
• 2012

본 시험은 윤작처리가 감자의 상품수량과 토양 화학성 및 미생물 활성에 미치는 영향을 평가하고 알맞은 작부체계를 확립하기 위하여 시험을 수행하였다. 작부체계내 콩과 보리를 도입하여 2년 2기작으로 감자를 윤작하였을 경우 총수량과 상품수량은 대조구인 연작구 대비 각각 31% 및 53% 정도 증가하였으며, 콩과 유채를 도입하여 2년 2기작으로 감자를 윤작하였을 경우 총수량과 상품수량은 각각 57% 및 75% 정도 증가하였다. 그리고 감자의 상품수량에 미치는 요인간 상관관계를 분석한 결과 상품수량은 토양미생물 활성, 특히 Biomass C 및 세균 밀도가 높을수록 증가하였고, 토양 pH, 유효인산, 치환성 칼슘함량이 높을수록 세균 밀도가 증가하였다. 따라서 윤작을 통해서 토양 화학성을 개량하고 미생물 밀도 및 활성을 증가시키면, 토양병 발생을 억제하고 감자의 생산성을 높일 수 있을 것으로 판단된다.

• Journal of Microbiology
• /
• 제42권4호
• /
• pp.267-277
• /
• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• 한국토양비료학회지
• /
• 제41권5호
• /
• pp.279-284
• /
• 2008

화산회토 감귤원에서 제초제를 사용하는 청경재배, 자연초종을 이용하는 자연초생재배, 켄터키블루그라스를 이용하는 인위초생재배를 4년간 동일한 방법으로 토양 및 시비관리를 하면서 토양의 물리성과 미생물체량, 토양인산효소 활성을 분석하였다. 자연초생재배가 청경재배보다 입단계수(>0.5 mm)는 26.7% 높았고 토양경도는 11.8 mm 낮았다. 토양의 용적밀도와 공극율은 차이가 없었다. 초생재배가 청경재배보다 인산효소 활성이 높았으며 토양 미생물체량은 인위초생재배가 $525.4mg\;kg^{-1}$로 청경재배보다 2배 이상 높았다. 결론적으로 초생재배는 입단형성이 잘되고 토양 경도가 개선되는 효과가 있었으며 토양 미생물활성이 높았다. 비화산회토 감귤농가 중 5년 이상 된 제초제를 이용하는 관행재배, 자연 초생재배 저농약, 유기농 인증 재배 감귤원 5개를 선정하여 감귤나무의 개화기인 5월에 토양을 채취 후 인지질 지방산과 토양인산효소 활성, 미생물체량을 분석하였다. 인지질지방산함량은 유기재배 감귤원이 $112.2n\;mol\;g^{-1}$로 관행재배보다 2배 이상 많았다. 인지질 지방산의 미생물지표에 따른 유기재배토양의 그램 음성세균은 15.1%, 방선균은 6.6%로 관행재배토양 보다 높았다. 유기재배 감귤원이 관행재배보다 토양 미생물체량은1.5배 정도 많았고 토양인산효소 활성은 17.6% 높았다.

• 한국토양비료학회지
• /
• 제49권6호
• /
• pp.783-788
• /
• 2016

Agricultural management of paddy soil depends on the effects of soil microbial activities. The present study evaluated the soil microbial community of 25 paddy soils in Gyeongnam Province by fatty acid methyl ester (FAME). The average of microbial communities in paddy soils were 32.2% of total bacteria, 16.7% of Gram-negative bacteria, 12.9% of Gram-positive bacteria, 2.0% of actinomycetes, 14.9% of fungi, and 1.3% of arbuscular mycorrhizal fungi. The communities of total bacteria (34.9%) and Gram-negative bacteria (19.4%) in soils with $30{\sim}35g\;kg^{-1}$ of organic matter were significantly larger than those in soils with other organic matter levels. However, soils with $20{\sim}30g\;kg^{-1}$ of organic matter had significantly low ratio of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ as compared with soils with $30{\sim}35g\;kg^{-1}$ of organic matter, indicating microbial stress decreased (p < 0.05). In principal component analyses of soil microbial communities, Gram-negative bacteria should be considered as a potential responsible factor for the obvious microbial community differentiation that was observed between the two different organic matter levels in paddy fields. Thus, soils containing $20{\sim}30g\;kg^{-1}$ of organic matter were responsible for strong effect on microbial biomass and stress in paddy fields.

• 한국물환경학회지
• /
• 제16권4호
• /
• pp.523-532
• /
• 2000

The purpose of this study was to investigate the effects of the hydraulic retention time (HRT) and organic loading rate (OLR) on microbial characteristics and treatment efficiency in sewage treatment using aerated submerged biological filter (ASBF) reactor. This reactor combines biodegradation of organic substrates by fixed biomass with a physical separation of biomass by filtration in a single reactor. Both simulated wastewater and domestic wastewater were used as feed solutions. The experimental conditions were a temperature of 17 to $27^{\circ}C$, a hydraulic retention time of 1 to 9hr, an organic loading rate of 0.47 to $3.84kg\;BOD/m^3{\cdot}day$ in ASBF reactor. This equipment could obtain a stable effluent quality in spite of high variation of influent loading rate. Total biomass concentration. biofilm thickness and biofilm mass increased an exponential function according to the increasing OLR. The relationships between water content and biofilm density were in inverse proportion. The percentage of backwash water to influent flow was almost 9%. The separation efficiency of biomass was the percentage of 91 to 92 in ASBF reactor. The sludge production rates in feed solutions of simulated wastewater and domestic wastewater were 0.14~0.26 kg VSS/kg BODrem, 0.43~0.48 kg VSS/kg BODrem, respectively.

• Journal of Microbiology and Biotechnology
• /
• 제28권2호
• /
• pp.305-313
• /
• 2018

A microbial consortium, TMC7, was enriched for the degradation of natural lignocellulosic materials under high temperature. TMC7 degraded 79.7% of rice straw during 15 days of incubation at $65^{\circ}C$. Extracellular xylanase was effectively secreted and hemicellulose was mainly degraded in the early stage (first 3 days), whereas primary decomposition of cellulose was observed as of day 3. The optimal temperature and initial pH for extracellular xylanase activity and lignocellulose degradation were $65^{\circ}C$ and between 7.0 and 9.0, respectively. Extracellular xylanase activity was maintained above 80% and 85% over a wide range of temperature ($50-75^{\circ}C$) and pH values (6.0-11.0), respectively. Clostridium likely had the largest contribution to lignocellulose conversion in TMC7 initially, and Geobacillus, Aeribacillus, and Thermoanaerobacterium might have also been involved in the later phase. These results demonstrate the potential practical application of TMC7 for lignocellulosic biomass utilization in the biotechnological industry under hot and alkaline conditions.

• 한국토양비료학회지
• /
• 제44권2호
• /
• pp.242-247
• /
• 2011

경남지역 밭 토양 25개소를 대상으로 2009년에 토양 화학성분과 미생물 다양성을 검토하고 토성, 지형 및 작물별 주요 변동요인을 주성분분석으로 해석하였다. 토양 유효인산 및 치환성 칼륨과 칼슘 함량은 적정수준 보다 높았으며 대부분의 토양 화학성분이 최소값과 최대값의 차이가 크게 나타났다. 지형적으로 산록경사지는 토양 유기물 함량과 치환성 칼륨 함량이 유의적으로 높았고 (p<0.05) 토성별 유기물 함량은 양토에서 높은 반면에 염류농도와 유효인산 함량은 사양토에서 높았으며 고구마 재배지의 치환성 칼슘함량은 감자 재배지에 비해 유의적으로 높았다. 지형별 밭토양의 곰팡이 개체수는 곡간 및 선상지가 하성평탄지 보다 유의적으로 많았고 토양 미생물체량과 탈수소효소 활성은 산록경사지가 다른 지형에 비해 유의적으로 높았다 (p<005). 토성에 따른 토양의 coliform 그룹은 미사질양토가 사양토와 양토에 비해 유의적으로 높았고 미생물체량은 양토가 미사질양토 보다 유의적으로 높았으나 (p<005) 작물별 미생물상과 토양 미생물체량 및 탈수소효소 활성은 유의적인 차이가 없었다. 주성분 분석결과 제1주성분이 32.2%, 제2주성분이 24.2%로서 전체 56.4%의 자료를 설명할 수 있었으며 제1주성분은 토양의 유효인산 함량이 가장 크게 기여하였다. 토양 바실러스균과 곰팡이균은 토양의 유기물 함량과 정의 상관관계를 보였으며 토양 pH는 형광성 슈도 모나스균과 정의 상관관계를 나타냈다.

• Ocean and Polar Research
• /
• 제33권1호
• /
• pp.21-34
• /
• 2011

We determined potential meso-scale benthic-pelagic ecosystem coupling in the north equatorial Pacific by comparing surface chl-a concentration with sediment bacterial abundance and adenosine triphosphate (ATP) concentration (indication of active biomass). Water and sediment samples were latitudinally collected between 5 and $11^{\circ}N$ along $131.5^{\circ}W$. Physical water properties of this area are characterized with three major currents: North Equatorial Current (NEC), North Equatorial Count Current (NECC), and South Equatorial Current (SEC). The divergence and convergence of the surface water occur at the boundaries where these currents anti-flow. This low latitude area ($5{\sim}7^{\circ}N$) appears to show high pelagic productivity (mean phytoplankton biomass=$1266.0\;mgC\;m^{-2}$) due to the supplement of high nutrients from nutrient-enriched deep-water via vertical mixing. But the high latitude area ($9{\sim}11^{\circ}N$) with the strong stratification exhibits low surface productivity (mean phytoplankton biomass=$603.1\;mgC\;m^{-2}$). Bacterial cell number (BCN) and ATP appeared to be the highest at the superficial layer and reduced with depth of sediment. Latitudinally, sediment BCN from low latitude ($5{\sim}7^{\circ}N$) was $9.8{\times}10^8\;cells\;cm^{-2}$, which appeared to be 3-times higher than that from high latitude ($9{\sim}11^{\circ}N$; $2.9{\times}10^8\;cells\;cm^{-2}$). Furthermore, sedimentary ATP at the low latitude ($56.2\;ng\;cm^{-2}$) appeared to be much higher than that of the high latitude ($3.3\;ng\;cm^{-2}$). According to regression analysis of these data, more than 85% of the spatial variation of benthic microbial biomass was significantly explained by the phytoplankton biomass in surface water. Therefore, the results of this study suggest that benthic productivity in this area is strongly coupled with pelagic productivity.

• Membrane and Water Treatment
• /
• 제14권1호
• /
• pp.35-45
• /
• 2023

Biofilms significantly affect the performance of wastewater treatment processes in which biodegradability of numerous microorganisms are actively involved, and various technologies have been applied to secure microbial biofilms. Understanding changes in biofilm characteristics by regulating expression of signaling molecules is important to control and regulate biofilms in membrane bioreactor, i.e., biofouling. This study investigated effects of addition of acyl-homoserine lactones (AHL) as a controllable factor for the microbial signaling system on biofilm formation of Pseudomonas aeruginosa PAO1 and multiple strains in membrane bioreactor. The addition of three AHL, i.e., C4-, C6-, and C8-HSL, at a concentration of 200 ㎍/L, enhanced the formation of the PAO1 biofilm and the degree of increases in the biofilm formation of PAO1 were 70.2%, 76.6%, and 72.9%, respectively. The improvement of biofilm formation of individual strains by C4-HSL was an average of 68%, and the microbial consortia increased by approximately 52.1% in the presence of 200 ㎍/L C4-HSL. CLSM images showed that more bacterial cells were present on the membrane surface after the AHL application. In the COMSTAT results, biomass and thickness were increased up to 2.2 times (PAO1) and 1.6 times (multi-strains) by C4-HSL. This study clearly showed that biofilm formation was increased by the application of AHL to individual strain groups, including PAO1 and microbial consortia, and significant increases were observed when 50 or 100 ㎍/L AHL was administered. This suggests that AHL application can improve the biofilm formation of microorganisms, which could yield an enhancement in efficiency of biofilm control, such as in various biofilm reactors including membrane bioreactor and bioflocculent systems in water/wastewater treatment processes.

• 한국토양비료학회지
• /
• 제44권1호
• /
• pp.146-159
• /
• 2011

The continuous increase in the production of metals and their subsequent release into the environment has lead to increased concentration of these elements in agricultural soils. Because microbes are involved in almost every chemical transformations taking place in the soil, considerable attention has been given to assessing their responses to metal contaminants. Short-term and long-term exposures to toxic metals have been shown to reduce microbial diversity, biomass and activities in the soil. Several studies show that microbial parameters like basal respiration, metabolic quotient, and enzymatic activities, including those of oxidoreductases and those involved in the cycle of C, N, P and other elements, exhibit sensitivity to soil metal concentrations. These have been therefore, regarded as good indices for assessing the impact of metal contaminants to the soil. Metal contamination has also been extensively shown to decrease species diversity and cause shifts in microbial community structure. Biochemical and molecular techniques that are currently being employed to detect these changes are continuously challenged by several limiting factors, although showing some degree of sensitivity and efficiency. Variations and inconsistencies in the responses of bioindicators to metal stress in the soil can also be explained by differences in bioavailability of the metal to the microorganisms. This, in turn, is influenced by soil characteristics such as CEC, pH, soil particles and other factors. Therefore, aside from selecting the appropriate techniques to better understand microbial responses to metals, it is also important to understand the prevalent environmental conditions that interplay to bring about observed changes in any given soil parameter.