• Journal of Forest and Environmental Science
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• v.30 no.2
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• pp.179-188
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• 2014

This research reports the effects of shifting cultivation on soil environment collecting samples from 0-5 cm soil depth from five locations viz. at Burburichhara, Maichchari, Longadu, Sukurchhari and Muralipara in Rangamati district of Chittagong Hill Tracts (CHTs). Soil analyses showed that fungal and bacterial population, microbial respiration and active microbial biomass, maximum water holding capacity, conductivity and moisture contents were significantly (at least $p{\leq}0.05$) lower in shifting cultivated soil compared to adjacent mixed tree plantations at all the sites. On an average in soils of 5 different shifting cultivated lands fungal population was $1.33{\times}10^5$ CFU/g dry soil and bacterial population $1.80{\times}10^7$ CFU/g dry soil and in mixed plantations fungal population was $1.70{\times}10^5$ and bacterial population $2.51{\times}10^7$ CFU/g dry soil. Organic matter and exchangeable Ca and Mg contents were significantly (at least $p{\leq}0.05$) lower and bulk density significantly (at least $p{\leq}0.05$) higher in shifting cultivated land in most of the locations compared to adjacent mixed tree plantations. Ratios of microbial respiration and organic carbon as well as active microbial biomass and organic carbon were distinctly lower and pH higher at 3 locations in shifting cultivated soils compared to mixed plantations. Findings of various soil properties, therefore, suggest that shifting cultivation has deteriorating effects on soil environment.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.918-921
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• 2000

A comparative study on rumen bacterial and protozoal population and fungal zoospores in cattle (Brahman$\times$Native) and swamp buffalo (Bubalus bubalis) was conducted. Forty animals, twenty of each, with same sex and similar age which were raised under similar condition in the Northeast of Thailand, were used. Rumen digesta were sampled immediately post slaughtering for total microscopic counts of bacteria, protozoa and fungal zoospores. It was found that total bacterial population were higher in swamp buffalo that those in cattle (1.6 vs $1.36{\times}10^{8}cells/ml$) having more population of cocci, rods and ovals. Lower rumen protozoal pupulation in swamp buffalo with lower numbers of Holotrichs and Entodiniomorphs were found as compared to those in cattle. Significant higher fungal zoospore counts were in swamp buffalo than those in cattle being 7.30 and $3.78{\times}10^6$, respectively. Study under electron microscope, revealed Anaeromyces sp. with acuminate apex were more predominant in the rumen of swamp buffalo. With these findings, cattle and swamp buffaloes showing differences in rumen bacterial, protozoal population and fungal zoospore counts, offer new additional information as why swamp buffaloes exhibit conditionally better than cattle especially during long dry season without green grass.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.121.1-121
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• 2003

Dispersal of Xanthomonas axonopodis pv. citri, causing citrus bacterial canker disease on Unshiu orange was investigated at previously infested plots at Seogwipo in Jeju island of Korea. The bacterial pathogen overwintered in lesions started to multiply at tate May, and disease firstly observed one month after detection of phage from lesions. The disease gradually increased, however, it dispersed non-directionally to nearby plants from inoculum sources. Diseased plants were aggregated to form a cluster throughout the experiment. Population dynamics of phage on symtomless leaf surface and the disease severity were compared in the nursery, Increase of phage population on symptomless leaf surface preceded one month to that of the disease severity Population of phage increased constantly from late July to October, however, the disease severity decreased from late August to late October. It was assumed that the decrease of disease severity might be due to disease-induced defoliation.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1645-1654
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• 2007

The total methylotrophic population associated with rice plants from different cultivars was enumerated at three different stages: vegetative, flowering, and harvesting. The bacterial population in the leaf, rhizosphere soil, endophytic in the stem and roots, and epiphytic in the florets and grains were determined from four rice cultivars, Il-mi, Nam-pyeoung, O-dae, and Dong-jin, sampled from three different field sites. The methylotrophic bacteria isolated on AMS media containing 0.5% methanol as the sole carbon source uniformly showed three distinct morphologies, which were recorded as separate groups and their distribution among the various samples was determined using the ecophysiological index. The growth stage at the time of sampling had a more significant effect on the methylotrophic population and their distribution than the field site or cultivar. A similar effect was also observed for the PPFMs, where their population in different plant parts increased from V10 to R4 and then decreased towards stage R9. A canonical discriminant analysis of the PPFM population from different parts of rice showed clear variations among the cultivars, sampled sites, and growth stages, although the variations were more prominent among the growth stages.

• Korean Journal of Poultry Science
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• v.18 no.3
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• pp.151-159
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• 1991

As a part of investigation on causes of drop in egg production in domestic chicken breeding farm, bacteriological contamination on air, feed, drinking water and artificial insemination instruments of randomly selected three farms was surveyed. Total bacterial population in the air was very high in all of the chicken houses tested and was not significantly different among these farms . However, total bacterial counts in the air of the problem house having egg drop problem and colibacillosis was higher than normal house within the problem farm. Bacterial population in the assorted feed was low before or after administration on the normal farm while it was much more increased after administration than before administration on the problem farm. Bacterial population of the drinking water in the source of water supply was very low and has no differences among farms tested. Also, bacterial population in the normal farm was not significantly different between source of water supply and after administration. However, population of total bacteria and coliform bacteria after administration was increased. Bacterial population was much higher in the artificial insemination instrument of problem farm than normal farm. However, this bacterial population in the problem farm was decreased to those of normal farm after these instruments were sanitized.

• Journal of Wetlands Research
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• v.7 no.2
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• pp.37-52
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• 2005

Vertical distribution of bacterial population and activities were compared between the muddy and sandy sediment of the tidal flat located in southern area of Ganghwa Island. The average of bacterial number and activities in mud flat was slightly higher than that in sand flat. Bacterial number was markedly increased at the sandflat during the investigation period, which seemed to be the result of increase of mud content. The number and activities of microorganisms in mudflat was comparable to that of the mangrove sediments. There was no differences in bacterial number with the depth, but the aminopeptidase activity and bacterial productivity were decreased markedly within 3~5cm depth of sediment due to the availability of carbon sources and molecular oxygen in pore water. The number and activities of microorganisms in mudflat did not correlated with the distribution of benthic microalgae; however, those in sand flat were closely correlated with the distribution of benthic microalgae. The distribution of marsh plant in the mudflat area might be the reason of the difference.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.283-288
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• 2008

Plant leaf surface is an important niche for diverse epiphytic microbes, including bacteria and fungi. Plant leaf surface plays a critical frontline defense against pathogen infections. The objective of our study was to evaluate the effectiveness of a starch-based super-absorbent polymer(SAP) combination, which enhances water potential and nutrient availability to plant leaves. We evaluated the effect of SAP on the maintenance of bacterial populations. In order to monitor bacterial populations in situ, a SAP mixture containing Pseudomonas syringae pv. tabaci that expressed recombinant green fluorescent protein(GFPuv) was spray-challenged onto whole leaves of Nicotiana benthamiana. The SAP combination treatment enhanced bacterial robustness, as indicated by disease severity and incidence. Unexpectedly, bacterial numbers were not significantly different between leaves treated with the SAP combination and those treated with water alone. Furthermore, young leaves treated with the SAP combination had more severe symptoms and a greater number of bacterial spots caused by primary and secondary infections compared to young leaves treated with the water control. In contrast, bacterial cell numbers did not statistically differ between the two groups, which indicated that measurement of viable GFP-based bacterial spots may provide a more sensitive methodology for assessing virulence of bacterial pathogens than methods that require dilution plating following maceration of bacterial-inoculated leaf tissue. Our study suggests that the SAP combination successfully increased bacterial aggressiveness, which could either be used to promote the ability of biological agents to control weedy plants or increase the robustness of saprophytic epiphytes against competition from potentially harmful microbes.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.341-346
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• 2011

To study the effects of salinity-sodicity on bacterial population and enzyme activities, soil samples were collected from the Bay of Yellow Sea, Incheon, South Korea. In the soils nearest to the coastline, pH, electrical conductivity ($EC_e$), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were greater than the criteria of saline-sodic soil, and soils collected from sites 1.5-2 km away from the coastline were not substantially affected by the intrusion and spray of seawater. Halotolerant bacteria showed similar trends, whereas non-tolerant bacteria and enzymatic activities had opposite trends. Significant positive correlations were found between EC, exchangeable $Na^+$, and pH with SAR and ESP. In contrast, $EC_e$, SAR, ESP, and exchangeable $Na^+$ exhibited significant negative correlations with bacterial populations and enzyme activities. The results of this study indicate that the soil chemical variables related with salinity-sodicity are significantly related with the sampling distance from the coastline and are the key stress factors, which greatly affect microbial and biochemical properties.

• Korean Journal of Veterinary Service
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• v.37 no.3
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• pp.203-212
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• 2014

Frog culture industry is not yet familiar but has much potential. Generally, in farm, the population density is higher than that of in nature and frog farm is not the exception. But when population density is high, it can easily leads to stressful condition, poor sanitation. When a disease occur, it is a primary factor that makes the population more susceptible and the results more grave. Because of severe Rhabditoidea- helminth infection and subsequent bacterial septicemia, 50~70% of the total population had been died in a farm in Jeong-sun in Gangwon-do and Chungju in Chungcheongbuk-do from late June, 2012 to September, 2012. Diseased frogs showed ruptured lung, bloody ascites, liver discoloration, myocardium weakness, congested kidney, microcytic anemia and so on. Enterobacteriacea, Citrobacter.sp, Cupriavidus metallidurans, Acinetobacter.sp were isolated as major bacterium that had caused septicemia in frogs. Among isolated bacterium, Cupriavidus metallidurans, Ewingella americana, Shewanella aquimarina and Pseudoalteromonas sp. have not reported as potential pathogens in frogs before. It is a good example that severe helminth infection in frogs can lead to secondary infection of bacteria.

• Journal of Ecology and Environment
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• v.31 no.2
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• pp.131-137
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• 2008

This study investigated the population densities and diversity of heterotrophic bacteria, and the rhizosphere-to-soil ratios (R/S) in the rhizosphere soil of halophyte Phragmites communis at the western coastal mudflats of Korea. The population densities of aerobic heterotrophic bacteria on the rhizosphere soil of P. communis were in the range of $3.3\;{\pm}\;0.9\;{\times}\;10^7\;{\sim}\;1.2\;{\pm}\;0.5\;{\times}\;10^8\;cfu\;g^{-1}$ dry weight (d. wt.). Population densities of amylolytic bacteria ranged from $1.1\;{\pm}\;0.2\;{\times}\;10^6$ to $3.0\;{\pm}\;1.2\;{\times}\;10^6\;cfu\;g^{-1}\;d.\;wt.$, while those of cellulolytic bacteria and proteolytic bacteria ranged from $5.6\;{\pm}\;2.3\;{\times}\;10^6$ to $1.5\;{\pm}\;0.3\;{\times}\;10^7\;cfu\;g^{-1}\;d.\;wt.$ and from $1.4\;{\pm}\;0.3\;{\times}\;10^6$ to $3.5\;{\pm}\;2.3\;{\times}\;10^7 \;cfu\;g^{-1}\;d.\;wt.$, respectively. The R/S ratios ranged from 2.26 to 6.89. Genetic (16S DNA) analysis of fifty-one isolates from the roots of P. communis suggested that the dominant species were closely related to the ${\gamma}$-proteobacteria group (18 clones) and the ${\alpha}$-proteobacteria group (14 clones). We found that halophyte species and mudflat environment both affected the rhizosphere bacterial communities.