• Advances in environmental research
• /
• 제2권1호
• /
• pp.61-80
• /
• 2013

Quantification of viable forms of microbial community (bacteria and fungi) using culture-dependent methods was done in order to characterize the indoor air quality (IAQ). Role of those factors, which may influence the concentration of viable counts of bacteria and fungi, like ventilation, occupancy, outdoor concentration and environmental parameters (temperature and relative humidity) were also determined. Volumetric-infiltration sampling technique was employed to collect air samples both inside and outside the schools. As regard of measurements of airborne viable culturable microflora of schools during one academic year, the level of TVMCs in school buildings was ranged between 803-5368 cfu/$m^3$. Viable counts of bacteria (VBCs) were constituted 63.7% of the mean total viable microbial counts where as viable counts of fungi (VFCs) formed 36.3% of the total. Mean a total viable microbial count (TVMCs) in three schools was 2491 cfu/$m^3$. Outdoor level of TVMCs was varied from 736-5855 cfu/$m^3$. Maximum and minimum VBCs were 3678-286 cfu/m3 respectively. Culturable fungal counts were ranged from 268-2089 cfu/$m^3$ in three schools. Significant positive correlation (p < 0.01) was indicated that indoor concentration of viable community reliant upon outdoor concentration. Temperature seemed to have a large effect (p < 0.05, p < 0.01) on the concentration of viable culturable microbial community rather than relative humidity. Consistent with the analysis and findings, the concentration of viable cultural counts of bacteria and fungi found indoors, were of several orders of magnitude, depending upon the potential of local, spatial and temporal factors, IO ratio appeared as a crucial indicator to identify the source of microbial contaminants.

• 미생물학회지
• /
• 제32권2호
• /
• pp.163-171
• /
• 1994

경유를 sandy loam 토양에서 농도별로 투여하여 토양미생물군집에 미치는 영향을 조사하였으며 또한 경우가 첨가된 토양에서 경유의 신속한 제거를 위해 실시한 bioremediation에 의한 영향을 측정하였다. 경유는 토양에서 16주 후 약 50% 내외의 잔류량을 나타내며 bioremediation 처리시 제거율은 60~95% 정도가 증가하여 16주 후 약 8~20 범위의 잔류량을 나타내었다. 토양에 경유가 첨가되었을 때에는 세균직접계수, 진균류의 균사 길이, 호기성 종속영양세균과 탄화수소 분해세균의 수가 최고 10 내지 100배 정도 증가하였다. Bioremediation 처리시에는 그 증가가 더욱 두드러져 각종 미생물 개체수 측정치가 최고 100배 내지 1000배까지 증가하였다. 경유가 fluorescein diacetate 가수분해 활성에 미치는 영향은 bioremediation 처리를 하지 않은 토양에서는 뚜렷한 증감의 경향이 없었으나 bioremediation 처리를 한 토양에서는 10배 내외의 활성의 증가를 보였으며 이러한 양상은 soil dehydrogenase 활성에서도 유사하게 나타났다.

• 한국토양비료학회지
• /
• 제48권5호
• /
• pp.442-450
• /
• 2015

This study was conducted to investigate the effect of Psy-2A-CrtI (PAC), a genetically modified (GM) rice with enhanced ${\beta}$-carotene, on the soil microbial community. The soil used to cultivate GM rice and its wild-type, Nakdong, was analyzed for population density, denaturing gradient gel electrophoresis (DGGE), and pyrosequencing. It was found that the bacterial, fungal and actinomycetes population densities of the PAC soils were within the range of those of the non-GM rice cultivar, Nakdong. The DGGE banding patterns of the GM and non-GM soils were also similar, suggesting that the bacterial community structures were stable within a given month and were unaffected by the presence of a GM plant. The pyrosequencing result showed a temporal difference in microorganism taxon and distribution ratio, but no significant difference between GM and non-GM was found. The persistence of the transgene DNA in the plant and surrounding soil were investigated for different time periods. There were differences in the persistence within the plant depending on the gene, but they could not be detected after 5 weeks. Also the transgenes were not detected in the surrounding soil. These results indicate that soil microbial communities are unaffected by the cultivation of a PAC rice within the experimental time frame.

• Proceedings of the National Institute of Ecology of the Republic of Korea
• /
• 제4권2호
• /
• pp.86-94
• /
• 2023

Climate change is more rapid in the Arctic than elsewhere in the world, and increased precipitation and warming are expected cause changes in biogeochemical processes due to altered microbial communities and activities. It is crucial to investigate microbial responses to climate change to understand changes in carbon and nitrogen dynamics. We investigated the effects of increased temperature and precipitation on microbial biomass and community structure in dry tundra using two depths of soil samples (organic and mineral layers) under four treatments (control, warming, increased precipitation, and warming with increased precipitation) during the growing season (June-September) in Cambridge Bay, Canada (69°N, 105°W). A phospholipid fatty acid (PLFA) analysis method was applied to detect active microorganisms and distinguish major functional groups (e.g., fungi and bacteria) with different roles in organic matter decomposition. The soil layers featured different biomass and community structure; ratios of fungal/bacterial and gram-positive/-negative bacteria were higher in the mineral layer, possibly connected to low substrate quality. Increased temperature and precipitation had no effect in either layer, possibly due to the relatively short treatment period (seven years) or the ecosystem type. Mostly, sampling times did not affect PLFAs in the organic layer, but June mineral soil samples showed higher contents of total PLFAs and PLFA biomarkers for bacteria and fungi than those in other months. Despite the lack of response found in this investigation, long-term monitoring of these communities should be maintained because of the slow response times of vegetation and other parameters in high-Arctic ecosystems.

• Mycobiology
• /
• 제47권2호
• /
• pp.230-241
• /
• 2019

The Great Sebkha of Oran is a closed depression located in northwestern of Algeria. Despite the ranking of this sebkha among the wetlands of global importance by Ramsar Convention in 2002, no studies on the fungal community in this area have been carried out. In our study, samples were collected from two different regions. The first region is characterized by halophilic vegetation and cereal crops and the second by a total absence of vegetation. The isolated strains were identified morphologically then by molecular analysis. The biotechnological interest of the strains was evaluated by testing their ability to grow at different concentration of NaCl and to produce extracellular enzymes (i.e., lipase, amylase, protease, and cellulase) on solid medium. The results showed that the soil of sebkha is alkaline, with the exception of the soil of cereal crops that is neutral, and extremely saline. In this work, the species Gymnoascus halophilus, Trichoderma gamsii, the two phytopathogenic fungi, Fusarium brachygibbosum and Penicillium allii, and the teleomorphic form of P. longicatenatum observed for the first time in this species, were isolated for the first time in Algeria. The halotolerance test revealed that the majority of the isolated are halotolerant. Wallemia sp. and two strains of G. halophilus are the only obligate halophilic strains. All strains are capable to secrete at least one of the four tested enzymes. The most interesting species presenting the highest enzymatic index were Aspergillus sp. strain A4, Chaetomium sp. strain H1, P. vinaceum, G. halophilus, Wallemia sp. and Ustilago cynodontis.

• 한국환경과학회지
• /
• 제30권5호
• /
• pp.379-389
• /
• 2021

Soil microorganism activity in an agricultural field is affected by various factors including climate conditions, soil chemical properties, and crop cultivation. In this study, we elucidate the correlation between microorganism activity and agricultural environment factors using the dehydrogenase activity (DHA) value, which is one of the indicators of soil microbial activity. As a result, the various factors noted above were related to the DHA value. Annual rainfall, soil Mg2+, bacterial and fungal diversities, types of crops, developmental stages, seasons, and cultivation status were highly correlated with the DHA value. Furthermore, next-generation sequencing (NGS) analysis was used to identify that the type of crop affected soil microbial compositions of both bacteria and fungi. Soil used for soybean cultivation showed the highest relative abundance for Verrucomicrobia, Planctomycetes, and Acidobacteria but Actinobacteria and Firmicutes had the lowest relative abundance. In the case of soil used for potato cultivation, Actinobacteria had the highest relative abundance but Proteobacteria had the lowest relative abundance. Armatimonadetes showed the highest relative abundance in soil used for cabbage cultivation. Among the fungal communities, Mortierellomycota had the highest relative abundance for soybean cultivation but the lowest relative abundance for cabbage cultivation; further, Rozellomycota, Chytridiomycota, and Cercozoa had the highest relative abundance for cabbage cultivation. Basidiomycota had the highest relative abundance for potato cultivation but the lowest relative abundance for soybean cultivation.

• The Plant Pathology Journal
• /
• 제39권2호
• /
• pp.207-219
• /
• 2023

Soft rot is a widespread, catastrophic disease caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) that severely damages the production of Amorphophallus spp. This study evaluated the rhizosphere bacterial and fungal communities in Pcc-infected and uninfected plants of two species of Amorphophallus, A. muelleri and A. konjac. Principal component analysis showed that the samples formed different clusters according to the Pcc infection status, indicating that Pcc infection can cause a large number of changes in the bacterial and fungal communities in the Amorphophallus spp. rhizosphere soil. However, the response mechanisms of A. muelleri and A. konjac are different. There was little difference in the overall microbial species composition among the four treatments, but the relative abundances of core microbiome members were significantly different. The relative abundances of Actinobacteria, Chloroflexi, Acidobacteria, Firmicutes, Bacillus, and Lysobacter were lower in infected A. konjac plants than in healthy plants; in contrast, those of infected A. muelleri plants were higher than those in healthy plants. For fungi, the relative abundances of Ascomycota and Fusarium in the rhizosphere of infected A. konjac plants were significantly higher than those of healthy plants, but those of infected A. muelleri plants were lower than those of healthy plants. The relative abundance of beneficial Penicillium fungi was lower in infected A. konjac plants than in healthy plants, and that of infected A. muelleri plants was higher than that of healthy plants. These findings can provide theoretical references for further functional research and utilization of Amorphophallus spp. rhizosphere microbial communities in the future.

• Journal of Microbiology and Biotechnology
• /
• 제27권4호
• /
• pp.678-684
• /
• 2017

The aim of this study was to elucidate the changes in the microbial community and biochemical properties of a traditional sweet paste during fermentation. PCR-denaturing gradient gel electrophoresis (DGGE) analysis showed that Aspergillus oryzae was the predominant species in the koji (the fungal mixture), and the majority of the fungi isolated belonged to two Zygosaccharomyces species in the mash. The bacterial DGGE profiles revealed the presence of Bacillus subtilis during fermentation, and Lactobacillus acidipiscis, Lactobacillus pubuzihii, Lactobacillus sp., Staphylococcus kloosi, and several uncultured bacteria were also detected in the mash after 14 days of main fermentation. Additionally, during main fermentation, amino-type nitrogen and total acid increased gradually to a maximum of $6.77{\pm}0.25g/kg$ and $19.10{\pm}0.58g/kg$ (30 days) respectively, and the concentration of reducing sugar increased to $337.41{\pm}3.99g/kg$ (7 days). The 180-day fermented sweet paste contained $261.46{\pm}19.49g/kg$ reducing sugar and its pH value remained at around 4.65. This study has used the PCR-DGGE technique to demonstrate the microbial community (including bacteria and fungi) in sweet paste and provides useful information (biochemical properties) about the assessment of the quality of sweet paste throughout fermentation.

• Preventive Nutrition and Food Science
• /
• 제16권2호
• /
• pp.165-173
• /
• 2011

Five types of meju were prepared from 100% defatted soybean (DFSG0), a mixture of 90% DFS and 10% glasswort (DFSG1), a mixture of 80% DFS and 20% glasswort (DFSG2), a mixture of 70% DFS and 30% glasswort (DFSG3), and a mixture of 60% DFS and 40% glasswort (DFSG4). Five types of kanjang were separately prepared from the 5 types of meju by ripening in brine for 6 months. The contents of certain minerals (Mg, Ca, Fe, Mn, and Zn), organic acids (citric acid, malic acid) and the antioxidative effects in the kanjang were increased in proportion to the glasswort content in the meju. However, the free amino acid contents in the kanjang were reduced in proportion to the glasswort content in the meju. DFSG1- and DFSG2-kanjang did not show distinct differences from DFSG0-kanjang based on aroma, flavor, and taste that were compared simply by panel tests. The bacterial and fungal community in the fermented meju and kanjang was not affected by the addition of glasswort to the meju-making process. Bacteria belonging to the Lactobacillus and Bacillus genera and the Lactobacillus family predominated, and yeasts belonging to the Saccharomyces genus and fungi belonging to the Aspergillus genus predominated in the fermented meju and kanjang. In conclusion, the glasswort was a supplement that nutritionally improved the kanjang (except for free amino acid contents) but didn't influence the growth of microorganisms that are responsible for the fermentation of meju and kanjang.

• Journal of Microbiology and Biotechnology
• /
• 제27권8호
• /
• pp.1409-1418
• /
• 2017

Two typical microbial communities from Chinese rice wine fermentation collected in Yichang city and Suzhou city in China were investigated. Both communities could ferment glutinous rice to rice wine in 2 days. The sugar and ethanol contents were 198.67 and 14.47 mg/g, respectively, for rice wine from Yichang city, and 292.50 and 12.31 mg/g, respectively, for rice wine from Suzhou city. Acetic acid and lactic acid were the most abundant organic acids. Abundant fungi and bacteria were detected in both communities by high-throughput sequencing. Saccharomycopsis fibuligera and Rhizopus oryzae were the dominant fungi in rice wine from Suzhou city, compared with R. oryzae, Wickerhamomyces anomalus, Saccharomyces cerevisiae, Mucor indicus, and Rhizopus microsporus in rice wine from Yichang city. Bacterial diversity was greater than fungal diversity in both communities. Citrobacter was the most abundant genus. Furthermore, Exiguobacterium, Aeromonas, Acinetobacter, Pseudomonas, Enterobacter, Bacillus, and Lactococcus were highly abundant in both communities.