• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.696-701
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• 2011

This study was conducted to investigate impacts of soil properties on microbial distribution in Jeonbuk orchard fields. Soil samples were collected from 110 sites cultivated with different fruit plants. The population of aerobic bacteria and fungi and the content of soil microbial biomass carbon (C) were found to increase with increasing silt content in the soils. Different activity of dehydrogenase was not observed among the different textures of soil. Microbial distribution, amount of microbial biomass C, and dehydrogenase activity in the soils were not significantly different among the topographic sites. However, in pear and grape fruit plant fields, coliform group of bacteria was found in relatively higher population, $133.0{\times}10^3\;CFU\;g^{-1}$ and $107.4{\times}10^3\;CFU\;g^{-1}$, respectively. Microbial groups were simplified and their density was reduced with increasing the cultivation periods of fruit plants. The soil microbial distribution was proportionally correlated with some of soil properties such as soil pH, soil organic matter (SOM) content, and exchangeable Mg content; in particular, the population of Bacillus sp. was proportionally correlated with soil pH and exchangeable Mg content. The amounts of microbial biomass C and the dehydrogenase activity in the soils were significantly correlated with the contents of SOM and exchangeable Ca ion (p<0.01).

• The Plant Pathology Journal
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• v.18 no.1
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• pp.30-35
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• 2002

The hyphal growth and biocontrol efficacy of Trichodemo harzianum in soil may depend on its interactions with biotic components of the soil environment. The effect of soil microbial biomass on growth and biocontrol efficacy of T. hanianum isolate ThzIDl-M3 (green fluorescent protein transformant) was investigated using artificially prepared different levels of soil microbial biomass (153,328, or 517ug biomass carbon per g of dry soil; BC). The hyphal growth of T. harzanum was significantly inhibited in the soil with 328 or 517 $\mu$g BC compared with 153 ug BC. When ThzIDl-M3 was added to the soils as an alginate pellet formulation, the recoverable population of ThzIDl-M3 varied, but the highest population occurred in 517ug BC. Addition of alginate pellets of ThzIDl-M3 to the soils (10 per 50 g) resulted in increased indigenous microbial populations (total fungi, bacterial fluorescent Pseudomonas app., and actinomycetes). Furthermore, colonizing ability of ThzIDl-M3 on sclerotia of Sclerotinia sclerotiorum was significantly reduced in the soil with high revel of BC. These results suggest that increased soil microbial biomass contributes to increased interactions between introduced T. harzianum and soil microorganisms, consequently reducing the biocontrol efficacy of 1T. harzianum.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.181-189
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• 1996

Several phosphate-solubilizing microorganisms were isolated in order to enhance the availability of insoluble phosphates accumulated in soils. Among the microorganisms, Aspergillus niger was selected and identified for this study. The phosphate-solubilizing activity. the phosphorus uptake by plants and the changes in soil microbial biomass by inoculation of Aspergillus niger were investigated. The uptake amounts of phosphorus by lettuce and pimiento were increased by inoculation of Aspergillus niger in all experimental treatments. There was negative correlation between the soil microbial biomass P and the soil phosphorus content. However the soil available phosphorus ($Y=-0.0007X^2+0.7126X^2-29.46$, $R=0.8283^{**}$) and the phosphorus absorption of plants ($Y=0.0049X^2-2.2352X+326.34$, $R=0.6350^*$) were significantly correlated to soil microbial biomass C on the positive section of quadric curve.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.204-210
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• 1998

The experiment was conducted to obtain the basic data required to characterize and improve rhizosphere environment of salt-accumulated greenhouse(SAG) soils by comparing the soil properties and the microbial flora of such soils to those of unprotected arable upland(UAU) soils. Soils were sampled from greenhouses and unprotected upland fields around the country. Microbial propulation, biomass C content and soil chemical properties were of interest. Population density of fluorescent Pseudomonas was high in UAU soils, while those of pathogenic Fusarium sp. and fluorescent Pseudomonas were low in SAG soils. With increasing soil organic matter(OM) content, the population densities of Bacillus sp., fluorescent Pseudomonas sp., Enterobacteriaceae, and microbial biomass C content increased. As soil electrical conductivity(EC) increased higher than $5.1dS\;m^{-1}$, the ratios of bacteria to fungi(B/F) and actinomycetes to fungi(A/F) and the population density of fluorescent Pseudomonas decreased remarkably. The soil pH was positively related to the population density of aerobic bacteria, while it was negatively related to that of fungi. The soil OM content was significantly correlated to the population densities of actinomycetes($r=0.226^*$). Bacillus sp.($r=0.334^{**}$), Enterobacteriaceae($r=0.276^*$), and the microbial biomass C content($R=0.439^{**}$). The population density of actinomycetes was also significantly correlated with soil exchangeable Ca($r=0.334^{**}$) and Mg($r=0.352^{**}$).

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.353-362
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• 2009

This study attempted to compare the litter decomposition rate of Arundinella hirta and Miscanthus sinensis var. purpurascens which collected from serpentine soil acting potentially toxic concentration of heavy metals and non-serpentine soil by using the microcosm method for 192 days under constant humidity and $23^{\circ}C$. The contents of Ni, Fe, Mg and Cr in the serpentine and nonserpentine soil originated litter showed high differences between them. The litter samples from serpentine site have lower C/N than non-serpentine litter, but the soluble carbohydrate content was shown almost similar between two plant litter. The mass loss rates of leaf litter from serpentine area were slower than those from non-serpentine site. During the experimental period, the remained dry weight of A. hirta and M. sinensis var. purpurascens litter collected from serpentine site were 64.7%, 65.0% of initial dry weight and litter samples from non-serpentine site showed 54.2%, 50.7%, respectively. K and Na were leached rapidly at the initial decomposition periods, but Ca showed immobilization and other metal elements reserved at the decomposing litter for a long time. The decomposing A. hirta litter from non-serpentine soil showed higher values of $CO_2$ evolution, microbial biomass-C, and microbial biomass-N than those in serpentine soil originated litter acting nutrient stresses and exhibited rapid decay rate. The microbial biomass and microbial respiration of decaying litter were positively correlated with litter decomposition rate, and these relationships showed more rapid slope in non-serpentine soil originated litter than that in serpentine soil.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.2
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• pp.122-128
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• 2013

This study was carried out to evaluate the soil dehydrogenase activity and microbial biomass C with soil type and land use in cropland of JeJu region. Soil chemical properties, dehydrogenase activity, and microbial biomass C were analyzed after sampling from upland (50 sites), orchard (50 sites), paddy (30 sites), horticultural facility (30 sites) in March. Average pH values was at 6.3 in upland soil, however soil chemical properties showed a large spatial variations in both orchard and horticultural facility soil. The Zn and Cu contents increased by the continuous application of pig manure compost in some citrus orchard soil. Soil dehydrogenase activity and microbial biomass C were higher in non-volcanic ash than in volcanic ash soil regardless of land use type. Soil dehydrogenase activity was two to four times higher in upland than in the others. It was at 38.7 ug TPF $24^{h-1}g^{-1}$ in non-volcanic ash of upland soil. Microbial biomass C content was very high in horticultural facility soil and it showed at 216.8 $mg\;kg^{-1}$ in non-volcanic ash. Soil dehydrogenase activity showed a positive correlation with organic matter ($r^2$=0.59), Zn ($r^2$=0.65), and Cu ($r^2$=0.66) in non-volcanic ash horticultural facility soil. There was a negative correlation ($r^2$=0.57) between soil organic matter and dehydrogenase activity in volcanic ash upland soil.

• Korean Journal of Environment and Ecology
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• v.26 no.6
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• pp.902-910
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• 2012

This study has been carried out to determine the effects of disturbances from wild boar grubbing on the functions of ecosystem. The experiments was performed in Mt. Jumbong of Long-term Ecological Research Sites of the Ministry of Environment. We measured soil physical properties, soil respiration($CO_2$), microbial biomass C, and soil enzyme activities from both disturbed and control plots. The disturbance sites were divided into two parts, mounds and pits. Soil organic matter contents were highest value at the control plots and lowest at the pit plots, respectively at 20.22% and 15.52%. The soil bulk densities were highest at the pit plots. Soil microbial biomass C and $CO_2$ evolution were significantly higher at the control plots compared to the disturbed plots. The results were positively correlated with soil organic matter contents. The cellulase activity and invertase activity in the soil showed similar pattern as the microbial biomass C and $CO_2$ evolution results. The cellulase activity and invertase activity in the soil were positively correlated with soil microbial biomass C. Soil organic matter contents seemed to affect the soil enzyme activities. The nitrate reductase activities were highest at the pit plots, which showed positive correlation with soil bulk density. The study results showed that the grubbing disturbances by wild boars induced the changes in soil properties, which affected soil microbial activities.

• The Korean Journal of Ecology
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• v.15 no.3
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• pp.267-279
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• 1992

The relationship between pb, zn, cd, and the microbial biomass and activity were investigated in three public park soils of central and outer london. Variability with distance from the roadside and profile were studied. The heavey metal concentrations were the highest in hampstead heath and hyde park with high trafic density and the lowest in hainault. The highest concentrations of heavy metals were found adjacent to the roadside in the upper parts of the soil profile. Dehydrogenase activity, adenosine tri-phosphate and ergosterol contents used as indices of micrbial biomass and activity, were generally higher in hainadult, and also higher in the upper pats of the soil profile. Simple regression analysis indicated that the microbial biomass and activity were affected significantly by moisture content, water holding capacity, total organic carbon, total nitrogen, and organic mater rather than heavy metal concentration. Highest inputs of nitrogen and carbon were associated with high inputs of heavey metals, all three being derived from vehicle emissions adjacent to the road. The hyde park and hampstead heath microbial populations were able to respond to the c and n input positively by increase in biomass and activity, whereas the hainault populations could not. This rsult suggrsts adaptation in he former to heavy matals, but not in the latter.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.254-264
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• 2010

To obtain an efficient natural lignocellulolytic complex enzyme, we screened an efficient lignocellulose-degrading composite microbial system (XDC-2) from composted agricultural and animal wastes amended soil following a long-term directed acclimation. Not only could the XDC-2 degrade natural lignocelluloses, but it could also secrete extracellular xylanase efficiently in liquid culture under static conditions at room temperature. The XDC-2 degraded rice straw by 60.3% after fermentation for 15 days. Hemicelluloses were decomposed effectively, whereas the extracellular xylanase activity was dominant with an activity of 8.357 U/ml on day 6 of the fermentation period. The extracellular crude enzyme noticeably hydrolyzed natural lignocelluloses. The optimum temperature and pH for the xylanase activity were $40^{\circ}C$ and 6.0. However, the xylanase was activated in a wide pH range of 3.0-10.0, and retained more than 80% of its activity at $25-35^{\circ}C$ and pH 5.0-8.0 after three days of incubation in liquid culture under static conditions. PCR-DGGE analysis of successive subcultures indicated that the XDC-2 was structurally stable over long-term restricted and directed cultivation. Analysis of the 168 rRNA gene clone library showed that the XDC-2 was mainly composed of mesophilic bacteria related to the genera Clostridium, Bacteroides, Alcaligenes, Pseudomonas, etc. Our results offer a new approach to exploring efficient lignocellulolytic enzymes by constructing a high-performance composite microbial system with synergistic complex enzymes.

• Journal of the korean society of oceanography
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• v.37 no.1
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• pp.35-44
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• 2002

To assess the relative contribution of bacterial and phytoplankton biomasses to particulate organic matter (POM) in the water column, microbial abundance and biomass were from two transects in the western channel of the Korea Strait in 1996. Bacterial abundance had a mean value of $5.9{\times}10^5$ cells/ml and chlorophyll-a averaged 0.14 ${\mu}g/l$. Bacterial abundance in the Korea Strait showed a positive relationship with chlorophyll-a concentration, while the distribution of POM did not covary with chlorophyll-a. Particulate organic carbon (POC) and nitrogen (PON) concentrations were greater in August than in October. Bacterial carbon (POC) and nitrogen (PON) concentrations were greater in August than in October. Bacterial carbon and nitrogen biomasses were 7.29 ${\mu}gC/l$ and 1.24 ${\mu}gN/l$, respectively, during the study periods. Bacterial biomass was larger in October than in August due to the autumn phytoplankton bloom. Phytoplankton biomass based on chlorophyll-a was 7.67 ${\mu}gC/l$ for carbon and 1.10${\mu}gN/l$l for nitrogen. The ratio of bacterial carbon (BC) to phytoplankton carbon (Cp) averaged 0.95 in the Korea Strait in 1996. Bacteria may play a more significant role in the dynamics of POM than phytoplankton do in August, with BC/Cp ratio of 1.26. The ratio of BC to Cp increased with a decrease in chlorophyll-a concentration. Averaged over all the samples in both cruises, the contribution of microbial biomass to POC and PON was about 43% and 51%, respectively. Bacterial assemblage constituted a significant fraction of POC (21%) and PON (27%). Phytoplankton accounted for 22% of POC and 24% of PON. Microbial biomass played a more important role in the dynamics of POC and PON in October than in August due to a significant increase in microbial biomass in the southern transect (transect-B) in October by the autumn phytoplankton bloom. This study showed that marine microbes may constitute a significant part in the reservoir of POM in the Korea Strait.