• 미생물학회지
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• 제52권1호
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• pp.49-58
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• 2016

부유 세균의 군집과 구별되는 생물막내 세균 군집은 다양한 수생태계에서 중요한 생태학적 역할을 수행한다. 자연계에서 생물막이 생태학적으로 중요함에도 불구하고, 남극 해양 환경에서 생물막 형성 과정 동안의 세균 군집 구조와 그들의 변화에 대한 연구는 수행되지 않았다. 본 연구에서, 남극 해양 환경에서 생물막 형성 초기 단계에서의 세균 군집 구조 변화를 16S rRNA 유전자의 pyrosequencing을 통해 수행하였다. 생물막내 전반적인 세균 군집은 주변의 해수의 군집과 매우 달랐다. 전체 세균 군집의 78.8%에서 88.3%를 차지한 Gammaproteobacteria와 Bacteroidetes의 상대적 풍부도는 생물막의 형성에 따라 급격하게 변하였다. Gammaproteobacteria는 생물막 형성 진행에 따라 증가하다가 (4일째에 75.7%), 7일째에 46.1%로 감소하였다. 반면, Bacteroidetes는 초기에서 중기로 갈수록 감소하다가 다시 증가하는 양상을 보이며, Gammaproteobacteria와 반대의 변화 양상을 나타내었다. 생물막 형성의 초기 과정에 우점 하는 OTU (>1%)들의 변화 양상은 시기에 따라 뚜렷한 차이를 보였다. Gammaproteobacteria에 속하는 종의 경우, 4일째까지 증가한 반면, 첫째날 가장 우점 하였던 문인 Bacteroidetes에 속하는 종은 4일째까지 감소한 후, 다시 증가하는 양상을 보였다. 흥미롭게, Pseudoalteromonas prydzensis가 67.4%를 차지하며 우점 하였는데, 이는 생물막 형성에 이 종이 중요한 역할을 수행함을 시사하는 것으로 보인다.

• Journal of Ecology and Environment
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• 제38권4호
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• pp.461-476
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• 2015

Global warming has accelerated glacial retreat in the high Arctic. The exposed glacier foreland is an ideal place to study chronosequential changes in ecosystems. Although vegetation succession in the glacier forelands has been studied intensively, little is known about the microbial community structure in these environments. Therefore, this study focused on how glacial retreat influences the bacterial community structure and its relationship with soil properties. This study was conducted in the foreland of the Midtre Lovénbreen glacier in Svalbard (78.9°N). Seven soil samples of different ages were collected and analyzed for moisture content, pH, soil organic carbon and total nitrogen contents, and soil organic matter fractionation. In addition, the structure of the bacterial community was determined via pyrosequencing analysis of 16S rRNA genes. The physical and chemical properties of soil varied significantly along the distance from the glacier; with increasing distance, more amounts of clay and soil organic carbon contents were observed. In addition, Cyanobacteria, Firmicutes, and Actinobacteria were dominant in soil samples taken close to the glacier, whereas Acidobacteria were abundant further away from the glacier. Diversity indices indicated that the bacterial community changed from homogeneous to heterogeneous structure along the glacier chronosequence/distance from the glacier. Although the bacterial community structure differed on basis of the presence or absence of plants, the soil properties varied depending on soil age. These findings suggest that bacterial succession occurs over time in glacier forelands but on a timescale that is different from that of soil development.

• Asian-Australasian Journal of Animal Sciences
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• 제22권6호
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• pp.900-905
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• 2009

We analyzed succession of the bacterial communities during composting of animal manure in three individual facilities. Polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) targeting for the bacterial 16S rRNA gene were used to clarify the changes of bacterial community throughout each composting process. Our study revealed that the bacterial community structures differed during the composting process. The bacterial community in composting of facility A showed little change throughout the process. In the compost sample from facility B, its community had a small shift as the temperature increased. In compost from facility C, the temperature dynamically changed; it was shown that various bacterial communities appeared and disappeared as follows: in the initial phase, the members of phylum Bacteroidetes dominated; in the thermophilic phase, some bacteria belonging to phylum Firmicutes increased; towards the end, the community structure consisted of three phyla, Bacteroidetes, Firmicutes, and Proteobacteria. This study provides some information about the bacterial community actually present in field-scale composting with animal manure.

• Asian-Australasian Journal of Animal Sciences
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• 제31권9호
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• pp.1464-1473
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• 2018

Objective: To describe in-depth sequencing, the bacterial community diversity and its succession during ensiling of whole-plant maize and subsequent exposure to air. Methods: The microbial community dynamics of fermented whole-plant maize for 60 days (sampled on day 5, 10, 20, 40, 60) and subsequent aerobic exposure (sampled on day 63 after exposure to air for 3 days) were explored using Illumina Miseq sequence platform. Results: A total of 227,220 effective reads were obtained. At the genus level, there were 12 genera with relative abundance >1%, Lactobacillus, Klebsiella, Sporolactobacillus, Norank-c-cyanobacteria, Pantoea, Pediococcus, Rahnella, Sphingomonas, Serratia, Chryseobacterium, Sphingobacterium, and Lactococcus. Lactobacillus consistently dominated the bacterial communities with relative abundance from 49.56% to 64.17% during the ensiling process. Klebsiella was also an important succession bacterium with a decrease tendency from 15.20% to 6.41% during the ensiling process. The genus Sporolactobacillus appeared in late-ensiling stages with 7.70% abundance on day 40 and 5.32% on day 60. After aerobic exposure, the Lactobacillus decreased its abundance from 63.2% on day 60 to 45.03% on d 63, and Klebsiella from 5.51% to 5.64%, while Sporolactobacillus greatly increased its abundance to 28.15%. These bacterial genera belong to 5 phyla: Firmicutes (relative abundance: 56.38% to 78.43%) was dominant, others were Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria. The bacterial communities clearly clustered into early-ensiling (d 5), medium-ensiling (d 10, d 20), late-ensiling (d 40, d 60), and aerobic exposure (d 63) clusters, with early- and late-ensiling communities more like each other than to the aerobic exposure communities. Conclusion: High-throughput sequencing based on 16S rRNA genes proved to be a useful method to explore bacterial communities of silage. The results indicated that the bacterial communities varied during fermentation and more dramatically during aerobic exposure. The study is valuable for understanding the mechanism of population change and the relationship between bacteria and ensilage characteristics.

• Asian-Australasian Journal of Animal Sciences
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• 제22권1호
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• pp.113-118
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• 2009

We investigated the structure of bacterial communities present in livestock manure-based composting processes and evaluated the bacterial succession during the composting processes. Compost samples were derived separately from swine manure, dairy manure and sewage sludge. The structure of the bacterial community was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) using universal eubacterial primers. The genus Bacillus and related genera were mainly detected following the thermophilic composting phase of swine and dairy manure composts, and the members of the phylum Bacteroidetes were mainly detected in the cattle manure waste-based and sewage sludge compost. We recovered and sequenced limited number of the bands; however, the PCR-DGGE analysis showed that predominant diversities during the composting processes were markedly changed. Although PCR-DGGE analysis revealed the presence of different phyla in the early stages of composting, the members of the phylum Firmicutes and Bacteroidetes were observed to be one of the predominant phyla after the thermophilic phase.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.373-384
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• 2016

The membrane-aerated biofilm reactor (MABR) is a promising municipal wastewater treatment process. In this study, two cross-flow MABRs were constructed to explore the carbon and nitrogen removal performance and bacterial succession, along with changes of influent loading shock comprising flow velocity, COD, and NH₄-N concentrations. Redundancy analysis revealed that the function of high flow velocity was mainly embodied in facilitating contaminants diffusion and biosorption rather than the success of overall bacterial populations (p > 0.05). In contrast, the influent NH₄-N concentration contributed most to the variance of reactor efficiency and community structure (p < 0.05). Pyrosequencing results showed that Anaerolineae, and Beta- and Alphaproteobacteria were the dominant groups in biofilms for COD and NH₄-N removal. Among the identified genera, Nitrosomonas and Nitrospira were the main nitrifiers, and Hyphomicrobium, Hydrogenophaga, and Rhodobacter were the key denitrifiers. Meanwhile, principal component analysis indicated that bacterial shift in MABR was probably the combination of stochastic and deterministic processes.

• The Plant Pathology Journal
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• 제37권6호
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• pp.662-672
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• 2021

Plant growth-promoting bacteria improve plant growth under abiotic stress conditions. However, their effects on microbial succession in the rhizosphere are poorly understood. In this study, the inoculants of Bacillus mesonae strain H20-5 were administered to tomato plants grown in soils with different salinity levels (EC of 2, 4, and 6 dS/m). The bacterial communities in the bulk and rhizosphere soils were examined 14 days after H20-5 treatment using Illumina MiSeq sequencing of the bacterial 16S rRNA gene. Although the abundance of H20-5 rapidly decreased in the bulk and rhizosphere soils, a shift in the bacterial community was observed following H20-5 treatment. The variation in bacterial communities due to H20-5 treatment was higher in the rhizosphere than in the bulk soils. Additionally, the bacterial species richness and diversity were greater in the H20-5 treated rhizosphere than in the control. The composition and structure of the bacterial communities varied with soil salinity levels, and those in the H20-5 treated rhizosphere soil were clustered. The members of Actinobacteria genera, including Kineosporia, Virgisporangium, Actinoplanes, Gaiella, Blastococcus, and Solirubrobacter, were enriched in the H20-5 treated rhizosphere soils. The microbial co-occurrence network of the bacterial community in the H20-5 treated rhizosphere soils had more modules and keystone taxa compared to the control. These findings revealed that the strain H20-5 induced systemic tolerance in tomato plants and influenced the diversity, composition, structure, and network of bacterial communities. The bacterial community in the H20-5 treated rhizosphere soils also appeared to be relatively stable to soil salinity changes.

• 한국식품과학회지
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• 제22권1호
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• pp.26-32
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• 1990

김치발효 지표로서 미생물군집의 특성을 밝히고자 하였다. 군집크기는 Gram염색법에 의한 현미경직접계수에 의하여 측정하였다. 실온$(15^{\circ}C)$에서 김치발효는 Gram양성균군집, 효모군집 그리고 Gram음성균군집이 순서적으로 천이되었다. Gram양성균군집은 김치를 발효시키는 유산균으로 구성되어 있다. 효모군집의 발달은 김치의 악취를 내는 원인이 되며, Gram음성균군집은 악취와 더불어 김치의 연화작용에 관계된다는 사실이 특정적이었다. 그리고, 외관상의 Gram음성균군은 Gram양성균군집 내의 개체군의 노화와 사멸을 평가하는데 이용될 수 있었다. 특히 저온$(5^{\circ}C)$ 김치발효에서는 효모군집과 Gram 음성균군집이 발달되지 않고 Gram양성균군집만이 발달됨을 알았다. 이 사실로부터 숙성된 김치는 Gram양성균군집에 의하여 만들어짐을 의미한다. 따라서 미생물군집의 발달과 크기는 김치발효의 지표로 이용될 수 있고, 또한 김치숙성도를 수십분 내에 예측하는데 중요한 방법이 될 수 있다.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.621-628
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• 1998

The "evolution" of a thing, a custom, an organ is thus by no means its progressus toward a goal, even less a logical progressus by the shortest route and with the least expendit ure of force, but a succession of more or less profound, mutually independent processes of subduing, plus the resistances they encounter, the attempts at transformation for the purpose of defense and reaction, and the results of successful counteractions. The form is fluid, but the "meaning" is even more so (Friedrich W. Nietzsche).

• Journal of Microbiology and Biotechnology
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• 제25권4호
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• pp.431-438
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• 2015

Ever since the ban on antibiotic growth promoters (AGPs), the livestock death rate has increased owing to pathogenic bacterial infections. There is a need of developing AGP alternatives; however, the mechanisms by which AGP enhances livestock growth performance are not clearly understood. In this study, we fed 3-week-old swine for 9 weeks with and without AGPs containing chlortetracycline, sulfathiazole, and penicillin to investigate the effects of AGPs on swine gut microbiota. Microbial community analysis was done based on bacterial 16S rRNA genes using MiSeq. The use of AGP showed no growth promoting effect, but inhibited the growth of potential pathogens during the early growth stage. Our results showed the significant increase in species richness after the stabilization of gut microbiota during the post-weaning period (4-week-old). Moreover, the swine gut microbiota was divided into four clusters based on the distribution of operational taxonomic units, which was significantly correlated to the swine weight regardless of AGP treatments. Taxonomic abundance analysis indicated a negative correlation between host weight and the abundance of the family Prevotellaceae species, but showed positive correlation to the abundance of the family Spirochaetaceae, Clostridiaceae_1, and Peptostreptococcaeae species. Although no growth performance enhancement was observed, the use of AGP inhibited the potential pathogens in the early growth stage of swine. In addition, our results indicated the ecological succession of swine gut microbiota according to swine weight. Here, we present a characterization of swine gut microbiota with respect to the effects of AGPs on growth performance.