• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1156-1168
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• 2020

Drought stress is threatening the growth and productivity of many economical crops. Therefore, it is necessary to establish innovative and efficient approaches for improving crop growth and productivity. Here we investigated the potentials of the cell-free extract of Actinobacteria (Ac) isolated from a semi-arid habitat (Al-Jouf region, Saudi Arabia) to recover the reduction in maize growth and improve the physiological stress tolerance induced by drought. Three Ac isolates were screened for production of secondary metabolites, antioxidant and antimicrobial activities. The isolate Ac3 revealed the highest levels of flavonoids, antioxidant and antimicrobial activities in addition to having abilities to produce siderophores and phytohormones. Based on seed germination experiment, the selected bioactive fraction of Ac3 cell-free extract (F2.7, containing mainly isoquercetin), increased the growth and photosynthesis rate under drought stress. Moreover, F2.7 application significantly alleviated drought stress-induced increases in H₂O₂, lipid peroxidation (MDA) and protein oxidation (protein carbonyls). It also increased total antioxidant power and molecular antioxidant levels (total ascorbate, glutathione and tocopherols). F2.7 improved the primary metabolism of stressed maize plants; for example, it increased in several individuals of soluble carbohydrates, organic acids, amino acids, and fatty acids. Interestingly, to reduce stress impact, F2.7 accumulated some compatible solutes including total soluble sugars, sucrose and proline. Hence, this comprehensive assessment recommends the potentials of actinobacterial cell-free extract as an alternative ecofriendly approach to improve crop growth and quality under water deficit conditions.

• Journal of Species Research
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• 제7권2호
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• pp.161-180
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• 2018

Fourteen bacterial strains, low10-4-1, J11015, 17J27-22, 17G22-9, 17G9-4, 17Bio_15, 17gy_33, 17SD1_21, Strain8, 17Sr1_17, J21014T, H31021, 17J49-9, and 17J80-6 assigned to the phylum Actinobacteria, Bacteroidetes, Deinococcus-Thermus, and Firmicutes were isolated from soil samples. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strains low10-4-1, J11015, 17J27-22, 17G22-9, 17G9-4, 17Bio_15, 17gy_33, 17SD1_21, Strain8, 17Sr1_17, J21014T, H31021, 17J49-9, and 17J80-6 were most closely related to Marmoricola aurantiacus (98.9%), Calidifontibacter indicus (99.8%), Gordonia soli (98.8%), Rhodococcus globerulus (99.5%), Pseudarthrobacter siccitolerans (99.1%), Hymenobacter qilianensis (98.7%), Hymenobacter terrae (99.0%), Deinococcus yunweiensis (99.2%), Deinococcus proteolyticus (99.7%), Domibacillus indicus (99.2%), Exiguobacterium mexicanum (100.0%), Kurthia senegalensis (99.1%), Lysinibacillus composti (99.6%), and Bacillus loiseleuriae (99.3%). These fourteen species have never been reported in Korea, therefore we report them here for the first time.

• 한국미생물·생명공학회지
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• 제43권1호
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• pp.65-78
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• 2015

순천만의 염생식물 근권에서 정주하는 세균의 분리를 위해 순천만에서 우점하는 자생식물인 칠면초 군락 3개 지점을 선발하여 샘플링 하였다. 시료는 marine broth, tryptic soy broth 한천배지를 통해 분리되었으며, 형태학적인 구분을 통해 순수분리되었다. 분리주의 16S rDNA를 분석하여 총 92 균주가 동정되었다. 이들의 유연관계 확인을 위한 계통수 작성 결과, 각각 firmicutes (56.5%), gamma-proteobacteria (29.3%), alpha-proteobacteria (5.4%), actinobacteria (5.4%), bacteroidetes (3.3%)에 속하였다. Shannon’s Diversity index (H')를 산출하였을 때 각각 1.675, 1.924, 2.04로, 채취 지점별로 종 다양성의 차이를 보였다.

• The Plant Pathology Journal
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• 제34권4호
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• pp.286-296
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• 2018

Maintenance of a beneficial microbial community, especially in the rhizosphere, is indispensable for plant growth and agricultural sustainability. In this sense, plant growth-promoting rhizobacteria (PGPR) have been extensively studied for their role in plant growth promotion and disease resistance. However, the impact of introducing PGPR strains into rhizosphere microbial communities is still underexplored. We previously found that the Proteus vulgaris JBLS202 strain (JBLS202) promoted growth of Kimchi cabbage and altered the relative abundance of total bacteria and Pseudomonas spp. in the treated rhizosphere. To extend these findings, we used pyrosequencing to analyze the changes in bacterial communities in the rhizosphere of Kimchi cabbage after introduction of JBLS202. The alterations were also evaluated by taxon-specific realtime PCR (qPCR). The pyrosequencing data revealed an increase in total bacteria abundance, including specific groups such as Proteobacteria, Acidobacteria, and Actinobacteria, in the treated rhizosphere. Time-course qPCR analysis confirmed the increase in the abundance of Acidobacteria, Actinobacteria, Alphaproteobacteria, and Betaproteobacteria. Furthermore, genes involved in nitrogen cycling were upregulated by JBLS202 treatment indicating changes in ecological function of the rhizosphere soil. Overall, these results indicate that introduction of JBLS202 alters both the composition and function of the rhizosphere bacterial community, which can have direct and indirect effects on plant growth. Therefore, we propose that long-term changes in bacterial composition and community-level function need to be considered for practical use of PGPRs.

• 미생물학회지
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• 제51권2호
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• pp.148-155
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• 2015

세균 16S rRNA 유전자 특이 프라이머를 기초로 하여 중합 효소연쇄반응을 이용하여 Pleurotus eryngii (큰느타리 버섯)의 내부에 존재하는 세균의 다양성을 조사하였다. 세균 16S rRNA의 라이브러리는 버섯 갓(BC, body cap)와 줄기(BS, body stipe)로 구성하였다. BC 20 클론은 네 그룹으로 구별되었고 가장 큰 그룹은 Firmicutes (클론의 40%) 있었다. 그러나, BS 20 클론은 여섯 그룹으로 나뉘어졌고 가장 큰 그룹은 Actinobacteria (클론의 40%) 있었다. 전체 버섯 내에 존재하는 세균 그룹은 그람양성 세균(62.5%) 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권8호
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• pp.1373-1380
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• 2018

Objective: This study was designed to investigate the effects of temperature and storage time on the evolution of bacterial communities in swine manure. Methods: Manure was stored at $-20^{\circ}C$, $4^{\circ}C$, $20^{\circ}C$, or $37^{\circ}C$ and sampled at 7-day intervals over 28 days of storage, for a total of 5 time points. To assess the bacterial species present, 16S ribosomal RNA gene sequences were analyzed using pyrosequencing. Results: After normalization, 113,934 sequence reads were obtained, with an average length of $466.6{\pm}4.4bp$. The diversity indices of the communities reduced as temperature and storage time increased, and the slopes of rarefaction curves decreased from the second week in samples stored at $-20^{\circ}C$ and $4^{\circ}C$. These results indicate that the richness of the bacterial community in the manure reduced as temperature and storage time increased. Firmicutes were the dominant phylum in all samples examined, ranging from 89.3% to 98.8% of total reads, followed by Actinobacteria, which accounted for 0.6% to 7.9%. A change in community composition was observed in samples stored at $37^{\circ}C$ during the first 7 days, indicating that temperature plays an important role in determining the microbiota of swine manure. Clostridium, Turicibacter, Streptococcus, and Lactobacillus within Firmicutes, and Corynebacterium within Actinobacteria were the most dominant genera in fresh manure and all stored samples. Conclusion: Based on our findings, we propose Clostridium as an indicator genus of swine manure decomposition in an anaerobic environment. The proportions of dominant genera changed in samples stored at $20^{\circ}C$ and $37^{\circ}C$ during the fourth week. Based on these results, it was concluded that the microbial communities of swine manure change rapidly as storage time and temperature increase.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1717-1723
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• 2010

The integrated fixed-film activated sludge (IFAS) system is a variation of the activated sludge wastewater treatment process, in which hybrid suspended and attached biomass is used to treat wastewater. Although the function and performance of the IFAS system are well studied, little is known about its microbial community structure. In this study, the composition and diversity of the bacterial community of suspended and attached biomass samples were investigated in a full-scale IFAS system using a high-throughput pyrosequencing technology. Distinct bacterial community compositions were examined for each sample and appeared to be important for its features different from conventional activated sludge processes. The abundant bacterial groups were Betaproteobacteria (59.3%), Gammaproteobacteria (8.1%), Bacteroidetes (5.2%), Alphaproteobacteria (3.9%), and Actinobacteria (3.2%) in the suspended sample, whereas Actinobacteria (14.6%), Firmicutes (13.6%), Bacteroidetes (11.6%), Betaproteobacteria (9.9%), Gammaproteobacteria (9.25%), and Alphaproteobacteria (7.4%) were major bacterial groups in the attached sample. Regarding the diversity, totals of 3,034 and 1,451 operational taxonomic units were identified at the 3% cutoff for the suspended and attached samples, respectively. Rank abundance and community analyses demonstrated that most of the diversity was originated from rare species in the samples. Taken together, the information obtained in this study will be a base for further studies relating to the microbial community structure and function of the IFAS system.

• Journal of Microbiology and Biotechnology
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• 제24권3호
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• pp.313-323
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• 2014

Significant alteration in the microbial community can occur across reclamation areas suffering subsidence from mining. A reclamation site undergoing fertilization practices and an adjacent coal-excavated subsidence site (sites A and B, respectively) were examined to characterize the bacterial diversity using 454 high-throughput 16S rDNA sequencing. The dominant taxonomic groups in both the sites were Proteobacteria, Acidobacteria, Bacteroidetes, Betaproteobacteria, Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, Deltaproteobacteria, Chloroflexi, and Firmicutes. However, the bacterial communities' abundance, diversity, and composition differed significantly between the sites. Site A presented higher bacterial diversity and more complex community structures than site B. The majority of sequences related to Proteobacteria, Gemmatimonadetes, Chloroflexi, Nitrospirae, Firmicutes, Betaproteobacteria, Deltaproteobacteria, and Anaerolineae were from site A; whereas those related to Actinobacteria, Planctomycetes, Bacteroidetes, Verrucomicrobia, Gammaproteobacteria, Nitriliruptoria, Alphaproteobacteria, and Phycisphaerae originated from site B. The distribution of some bacterial groups and subgroups in the two sites correlated with soil properties and vegetation due to reclamation practice. Site A exhibited enriched bacterial community, soil organic matter (SOM), and total nitrogen (TN), suggesting the presence of relatively diverse microorganisms. SOM and TN were important factors shaping the underlying microbial communities. Furthermore, the specific plant functional group (legumes) was also an important factor influencing soil microbial community composition. Thus, the effectiveness of 454 pyrosequencing in analyzing soil bacterial diversity was validated and an association between land ecological system restoration, mostly mediated by microbial communities, and an improvement in soil properties in coal-mining reclamation areas was suggested.

• 한국환경농학회지
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• 제30권4호
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• pp.367-376
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• 2011

논 토양의 미생물 생태 다양성을 조사하기 위한 효과적인 방법으로 qRT-PCR을 적용하고자 본 연구를 수행하였다. 논 토양 미생물의 gDNA를 분리하기 위하여 Mo Bio kit를 사용한 효과적이고 안정적인 gDNA 분리 방법을 확립하였다. 논 토양 미생물 다양성을 qRT-PCR로 검출하기 위하여 bacteria를 세분한 ${\alpha}$-Proteobacteria, ${\beta}$-Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes 다섯 가지 문과 전체 bacteria, 전체 fungi를 구분할 수 있는 특이 primer set을 선정하여 다양한 조건의 시험을 통하여 최종 조건을 확립하였으며 재현성 실험을 통하여 방법의 유의성을 검증하였다.

• Journal of Species Research
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• 제7권3호
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• pp.222-230
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• 2018

Six bacterial strains 18JY42-3, 18SH, 18JY76-11, 17J11-11, 18JY14-14, and 18JY15-11 assigned to the phylum Proteobacteria, Firmicutes, and Actinobacteria were isolated from soil samples in Korea. The Cohnella species, strain 18JY42-3 was Gram-stain-positive, short rod-shaped and beige-colored. The Methylobacterium species, strains 18SH and 18JY76-11 were Gram-stain-negative, short rod-shaped and pink-colored. The Microterricola species, strain 17J11-11 was Gram-stain-positive, short rod-shaped and yellow-colored. The Paenarthrobacter species, strains 18JY14-14 and 18JY15-11 were Gram-stain-positive, short rod-shaped and white-colored. Phylogenetic analysis based on 16S rRNA gene sequence showed that strains 18JY42-3, 18SH, 18JY76-11, 17J11-11, 18JY14-14, and 18JY15-11 were most closely related Cohnella rhizosphaerae (MH497628; 98.8%), Methylobacterium goesingense (MH497632; 99.1%), Methylobacterium populi (MH497635; 99.9%), Microterricolagilva (MH504108; 98.4%), Paenarthrobacter nicotinovorans (MH497641; 100%), and Paenarthrobacter nitroguajacolicus (MH497646; 99.2%), respectively. All the six unrecorded strains showed resistance to UV radiation. This is the first report of these six species in Korea.