• Journal of Microbiology
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• 제44권3호
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• pp.363-368
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• 2006

In this study, native Byadyrhizobium strains were isolated from the host plant, Glycine max, harvested from fields in Madhya Pradesh, India, and were typed by Iytic rhizobiophages. Eight indigenous (Soy2, ASR011, ASR031, ASR032, MSR091, ISR050, ISR076 and ISR078) and two exotic strains (USDA123 and CB1809), all of which evidenced a distinct reaction with six phages, were employed in this study. The symbiotic interaction of these strains was studied initially using soybean cultivar JS335 in a sand culture in a controlled environment, and the efficiency was assessed based on the nodule number, nodule dry weight, plant dry weight, nitrogenase activity, and total accumulation of N per plant. Symbiotic effectiveness was found to be highest with the native phage-sensitive isolate ASR011, whereas it was at a minimum with the phage-resistant isolates, ISR050 and ISR078. Additionally, the effectiveness of these strains was evaluated using six soybean cultivars belonging to different maturity groups; namely, Brags, Lee, Pusa20, PK416, JS33S and NRC37. Analysis of variance data evidenced significant differences due to both symbionts, for the majority of the tested parameters. The CB1809, USDA123, and ASR011 strains evidenced relatively superior symbiotic effectiveness with soybean cultivars Brags, Lee and JS335. Strain ISR078 evidenced no significant responses with any of the cultivars. The ASR031 strain performed moderately well with all tested cultivars. The symbiotic response of all the strains was quite poor with cultivar PK416. Our studies showed that a significant relationship existed between the phage sensitivity and symbiotic efficiency of the bacterial strains with the host-cultivars.

• The Plant Pathology Journal
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• 제38권6호
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• pp.583-592
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• 2022

Root-knot nematode disease is a widespread and catastrophic disease of tobacco. However, little is known about the relationship between rhizosphere bacterial community and root-knot nematode disease. This study used 16S rRNA gene sequencing and PICRUSt to assess bacterial community structure and function changes in rhizosphere soil from Meloidogyne incognita-infected tobacco plants. We studied the rhizosphere bacterial community structure of M. incognita-infected and uninfected tobacco plants through a paired comparison design in two regions of tobacco planting area, Yuxi and Jiuxiang of Yunnan Province, southwest China. According to the findings, M. incognita infection can alter the bacterial population in the soil. Uninfested soil has more operational taxonomic unit numbers and richness than infested soil. Principal Coordinate Analysis revealed clear separations between bacterial communities from infested and uninfested soil, indicating that different infection conditions resulted in significantly different bacterial community structures in soils. Firmicutes was prevalent in infested soil, but Chloroflexi and Acidobacteria were prevalent in uninfested soil. Sphingomonas, Streptomyces, and Bradyrhizobium were the dominant bacteria genera, and their abundance were higher in infested soil. By PICRUSt analysis, some metabolism-related functions and signal transduction functions of the rhizosphere bacterial community in the M. incognita infection-tobacco plants had a higher relative abundance than those uninfected. As a result, rhizosphere soils from tobacco plants infected with M. incognita showed considerable bacterial community structure and function alterations.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권3호
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• pp.194-210
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• 2022

Human milk contains a number of nutritional and bioactive molecules including microorganisms that constitute the so-called "Human Milk Microbiota (HMM)". Recent studies have shown that not only bacterial but also viral, fungal, and archaeal components are present in the HMM. Previous research has established, a "core" microbiome, consisting of Firmicutes (i.e., Streptococcus, Staphylococcus), Proteobacteria (i.e., Serratia, Pseudomonas, Ralstonia, Sphingomonas, Bradyrhizobium), and Actinobacteria (i.e., Propionibacterium, Corynebacterium). This review aims to summarize the main characteristics of HMM and the role it plays in shaping a child's health. We reviewed the most recent literature on the topic (2019-2021), using the PubMed database. The main sources of HMM origin were identified as the retrograde flow and the entero-mammary pathway. Several factors can influence its composition, such as maternal body mass index and diet, use of antibiotics, time and type of delivery, and mode of breastfeeding. The COVID-19 pandemic, by altering the mother-infant dyad and modifying many of our previous habits, has emerged as a new risk factor for the modification of HMM. HMM is an important contributor to gastrointestinal colonization in children and therefore, it is fundamental to avoid any form of perturbation in the HMM that can alter the microbial equilibrium, especially in the first 100 days of life. Microbial dysbiosis can be a trigger point for the development of necrotizing enterocolitis, especially in preterm infants, and for onset of chronic diseases, such as asthma and obesity, later in life.

• Journal of Microbiology and Biotechnology
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• 제33권10호
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• pp.1299-1308
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• 2023

Carya cathayensis is an important economic nut tree that is endemic to eastern China. As such, outbreaks of root rot disease in C. cathayensis result in reduced yields and serious economic losses. Moreover, while soil bacterial communities play a crucial role in plant health and are associated with plant disease outbreaks, their diversity and composition in C. cathayensis are not clearly understood. In this study, Proteobacteria, Acidobacteria, and Actinobacteria were found to be the most dominant bacterial communities (accounting for approximately 80.32% of the total) in the root tissue, rhizosphere soil, and bulk soil of healthy C. cathayensis specimens. Further analysis revealed the abundance of genera belonging to Proteobacteria, namely, Acidibacter, Bradyrhizobium, Paraburkholderia, Sphaerotilus, and Steroidobacter, was higher in the root tissues of healthy C. cathayensis specimens than in those of diseased and dead trees. In addition, the abundance of four genera belonging to Actinobacteria, namely, Actinoallomurus, Actinomadura, Actinocrinis, and Gaiella, was significantly higher in the root tissues of healthy C. cathayensis specimens than in those of diseased and dead trees. Altogether, these results suggest that disruption in the balance of these bacterial communities may be associated with the development of root rot in C. cathayensis, and further, our study provides theoretical guidance for the isolation and control of pathogens and diseases related to this important tree species.

• 한국환경과학회지
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• 제33권1호
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• pp.27-41
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• 2024

In this study, we evaluated productivity, soil physiochemical properties, and soil microbial characteristics in Kimchi cabbage(Brassica rapa subsp. pekinensis) cultivation within a highland environment during summer. Specifically, we examined the effect of different cropping systems, namely monoculture and rotation with soybean, over an 8-year cropping period. The results of our investigation revealed that significant differences were absent in terms of yield and soil physiochemical properties between the two cropping systems. However, microbial characteristics exhibited distinctive patterns. Bacterial diversity was significantly higher in the rotation system that in the monoculture, whereas fungal diversity demonstrated a preference for rotation although the result was not significant. Our findings identified the presence of Bradyrhizobium stylosanthis, a nitrogen-fixation symbiont, as an indicator ASV (amplicon sequence variant) in the rotation system, where it displayed significantly higher abundances. These observations suggest a potential positive effect of the rotation system on nitrogen fixation. Notably, throughout the cultivation period, both cropping systems did not exhibit critical disease incidences. However, Fusarium oxysporum, a well-known pathogen responsible for inducing fusarium wilt disease in Kimchi cabbage, was detected with significantly higher abundance in the monoculture system. This finding raises concerns about the potential risk associated with Kimchi cabbage cultivation in a long-term monoculture system.

• Journal of Microbiology and Biotechnology
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• 제34권3호
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• pp.570-579
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• 2024

Root-nodule nitrogen-fixing bacteria are known for being specific to particular legumes. This study isolated the endophytic root-nodule bacteria from the nodules of legumes and examined them to determine whether they could be used to promote the formation of nodules in other legumes. Forty-six isolates were collected from five leguminous plants and screened for housekeeping (16S rRNA), nitrogen fixation (nifH), and nodulation (nodC) genes. Based on the 16S rRNA gene sequencing and phylogenetic analysis, the bacterial isolates WC15, WC16, WC24, and GM5 were identified as Rhizobium, Sphingomonas, Methylobacterium, and Bradyrhizobium, respectively. The four isolates were found to have the nifH gene, and the study confirmed that one isolate (GM5) had both the nifH and nodC genes. The Salkowski method was used to measure the isolated bacteria for their capacity to produce phytohormone indole acetic acid (IAA). Additional experiments were performed to examine the effect of the isolated bacteria on root morphology and nodulation. Among the four tested isolates, both WC24 and GM5 induced nodulation in Glycine max. The gene expression studies revealed that GM5 had a higher expression of the nifH gene. The existence and expression of the nitrogen-fixing genes implied that the tested strain had the ability to fix the atmospheric nitrogen. These findings demonstrated that a nitrogen-fixing bacterium, Methylobacterium (WC24), isolated from a Trifolium repens, induced the formation of root nodules in non-host leguminous plants (Glycine max). This suggested the potential application of these rhizobia as biofertilizer. Further studies are required to verify the N₂-fixing efficiency of the isolates.

• 환경생물
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• 제42권2호
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• pp.143-157
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• 2024

As part of the research program "Freshwater Prokaryotic Organisms Research and Discovery," freshwater samples were collected from the Nakdonggang River. After plating the samples on several culture media and incubating aerobically, approximately 900 bacterial strains were isolated and identified using 16S rRNA gene sequences. Among the bacterial isolates showing higher than 98.7% 16S rRNA gene sequence similarity with those of already confirmed bacterial species previously unreported in Korea, 29 strains were selected. These strains were phylogenetically diverse and belonged to 3 phyla, 6 classes, 13 orders, and 21 genera. At the genus level, these previously unreported species were found to be affiliated with Novosphingobium, Sphingomonas, Polymorphobacter, Croceibacterium, Devosia, Endobacterium, Agaricicola, Bradyrhizobium, Paracoccus, and Pseudotabrizicola of the class Alphaproteobacteria; Undibacterium, Azonexus, and Dechloromonas of the class Betaproteobacteria; Acinetobacter and Budvicia of the class Gammaproteobacteria; Streptomyces, Nocardioides, Mycobacterium, and Cellulomonas of the phylum Actinomycetota; Flavobacterium and Pedobacter of the phylum Bacteroidota. These species were further characterized by examining their Gram reaction, colony and cell morphologies, biochemical properties, and phylogenetic positions. Detailed descriptions of these 29 previously unreported species are provided.

• 한국토양비료학회지
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• 제24권3호
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• pp.210-218
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• 1991

질소무시용하(窒素無施用下)에서 소석회(消石灰), 고토석회(苦土石灰), 탄산석회(炭酸石灰)는 중화량(中和量), 황산석회(黃酸石灰)는 10a당(糖) 150kg시용(施用)하고 비닐피복후(被覆後) $40{\times}25cm$ 재식거리(栽植距離)로 1989년(年) 4월(月) 26일(日) 파종(播種)하여 호남(湖南) 작시(作試) 선발(選拔) 우량질소(優良窒素) 고정균(固定菌)(B. sp HCR-46)을 종자(種字) 1입당(粒當) $8.2{\times}10^7$ cell의 농도(濃度)로 접종(接種)한뒤 영호(嶺湖)땅콩의 종실성분(種實成分)의 변화(變化)를 조사(調査)한 결과(結果)는 다음과 같다. 1. 땅콩에 착생(着生)한 근류수, 근류건중(根瘤乾重) 그리고 지하부건중(地下部乾重)은 근류균(根瘤菌) 접종(接種)으로 증가(增加)되었으며, 석회비종별(石灰肥種別)로는 탄산석회(炭酸石灰)>고토석회(苦土石灰)>소석회(消石灰)>무시용(無施用)>황산석회순(黃酸石灰順)이었다. 2. 근류균(根瘤菌) 접종(接種)으로 잎과 줄기중(中) T-N, $K_2O$, MgO, Allantoin, Ammonia, 유리(遊離)아미노산함량(酸含量), 엽록소함량(葉綠素含量)은 증가(增加)되었으나 Nitrate 와 줄기중(中) 전당(全糖), 전분(澱粉)의 함량(含量)은 감소(減少)되었다. 3. 잎과 줄기중(中) T-N, 유리(遊離)아미노산(酸), 엽록소함량(葉綠素含量)은 탄산석회시용구(炭酸石灰施用區)에서, $K_2O$, MgO, Allantoin, Ammonia 함량(含量)은 고토석회시용구(苦土石灰施用區)에서, CaO와 Nitrate함량(含量)은 소석회시용구(消石灰施用區)에서 가장 높았다. 4. 줄기중(中) 전당함량(全糖含量)은 황산석회(黃酸石灰)>무시용(無施用)>소석회(消石灰)>탄산석회(炭酸石灰)>고토석회순(苦土石灰順)이었다. 5. 야산개간지(野山開墾地)에서 석회비종별(石灰肥種別) 토양개량효과를 보면 탄산석회(炭酸石灰)는 산도교정력(酸度矯正力)과 Ca공급력(供給力)이 우수(優秀)했으며, 고토석회(苦土石灰)는 Mg공급력(供給力)이 우수(優秀)하였다. 6. 근류균(根瘤菌) 접종(接種)으로 주경장(主莖長), $m^2$당협수가 유의적(有意的)으로 증가(增加)했으며 종실수량(種實收量)은 무접종(無接種)보다 64%증가(增加)되었다. 석회비종별(石灰肥種別)로 보면 주경장(主莖長), 분지수, 종실수량(種實收量)은 탄산석회(炭酸石灰)>고토석회(苦土石灰)>소석회(消石灰)>황산석회(黃酸石灰)>무시용순(無施用順)이었다.

• 한국토양비료학회지
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• 제26권3호
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• pp.197-203
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• 1993

항생제 내성변이 균주 HCR-46 $str^{r}cep^{r}$과 CB756 $str^{r}rif^{r}$를 종자피복방법(種子被覆方法)으로 땅콩에 접종(接種)하여 3처리(處理)의 온도(溫度)에 생육(生育)시켜 근권(根圈)에서 접종균주(接種菌株)의 밀도(密度)와 근류형성(根瘤形成) 경합(競合)등에 관하여 조사하였다. 접종균주(接種菌株)는 땅콩의 생육(生育)과 함께 증식(增殖)되었고 식물체(植物體) 뿌리 g당(當) 증식속도(增殖速度)는 파종후(播種後) 10~15일(日) 사이에 가장 빨랐다. 온도간(溫度間) 증식속도(增殖速度)는 $28^{\circ}C$>$34^{\circ}C$>$22^{\circ}C$순(順)이었으며 접종균주간(接種菌株間)에는 HCR-46 $str^{r}cep^{r}$ 균수(菌洙)가 CB756 $str^{r}rif^{r}$ 균주(菌株)보다 $22^{\circ}C$와 $28^{\circ}C$에서는 더 높았고, $34^{\circ}C$에서는 비슷하였다. HCR-46 $str^{r}cep^{r}$ 및 CB756 $str^{r}if^{r}$ 균주(菌株)를 단일접종시(單一接種時) 처리(處理)한 모든 온도(溫度)에서 근류(根瘤)의 대부분이 각 균주(菌株)에 의하여 점유(占有)되었으나, 2개(個) 균주(菌株)를 혼합접종시(混合接種時)에는 $22^{\circ}C$와 $28^{\circ}C$에서는 HCR-46 $str^rcep^r$ 균주(菌株)에 의한 근류(根瘤) 점유율(占有率)이 CB756 $str^{r}rif^{r}$에 비(比)하여 월등(越等)히 높았고 $34^{\circ}C$에서는 2균주(菌株)가 비슷한 비율(比率)로 점유(占有)하였다. 식물체(植物體) 건물중(乾物重), 근류형성능(根瘤形成能), 질소흡수량(窒素吸收量), 질소고정력(窒素固定力)은 대체로 $28^{\circ}C$>$34^{\circ}C$>$22^{\circ}C$순(順)이었으며, CB756 $str^{r}if^{r}$ 균주(菌株)보다 HCR-46 $str^{r}cep^{r}$ 또는 이들 2개혼합(個混合) 균주(菌株) 접종(接種)이 더 높았다.

• 한국토양비료학회지
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• 제27권2호
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• pp.136-146
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• 1994

대두 근류균 공생에서 뿌리분비물에 대한 근류균의 화학주성이 근류형성에 미치는 영향을 조사 연구한 결과는 다음과 같다. 2mM proline에 대한 표준균주와 변이주의 화학주성비는 KCTC 2422는 3.1, LPN-100은 1.3, LCR-101은 1.0이었으며 전형적인 Slow growing Rhizobia였다. 팔달 및 백운의 뿌리분비물 추출액에 대한 근류균의 화학주성비는 KCTC 2422는 3.5/3.2 이고 LPN-100은 1.3/1.4이며 LCR-101은 1.4/1.4정도였다. Dowex 칼럼으로부터 용출시킨 Fraction I, II, III에 대한 화학주성비는 Fraction I>II>III순이었고 중성분획인 Glucose와 Ribose, 양성분획인 Aspartic acid와 Glutamine, 음성분획인 Citric acid, Succinic acid에 대한 화학주성비는 공히 $10^{-3}M$일때 가장높은 화학주성비를 나타내었다. 근류형성의 정도는 KCTC 2422는 접종후 7일경부터 Nitrogenase 활성이 나타나기 시작하며 LCR-101은 15일 이후에 Nitrogenase 활성이 나타났으며 LPN-100은 전혀 근류를 형성하지 않아 근류균의 화학주성이 숙주인식의 초기과정에 영향을 미쳤음을 확인할 수 있었다.