• Journal of Microbiology and Biotechnology
• /
• 제17권8호
• /
• pp.1300-1307
• /
• 2007

This study assessed the possible role of different traits in selected plant growth-promoting rhizobacteria (PGPR) for improving wheat growth and yield under natural conditions. Rhizobacteria exhibiting 1-aminocyclopropane-1-carboxylate (ACC)-deaminase activity were isolated and screened for their growth-promoting activity in wheat under axenic conditions. Five isolates belonging to Pseudomonas and one Burkholderia caryophylli isolate that showed promising performances under axenic conditions were selected and characterized for in vitro ACC-deaminase activity, chitinase activity, auxin production, P solubilization, and root colonization. These isolates were then used as inocula for wheat cultivated under natural conditions in pot and/or field trials. Significant increases in root elongation, root weight, tillers per pot, 1,000-grain weight, and grain and straw yields were observed in response to inoculation with PGPR in the pot trials. Inoculation with these PGPR was also effective under field conditions and increased the wheat growth and yield significantly. However, the efficacy of the strains was inconsistent under the axenic, pot, and field conditions. Pseudomonas fluorescens ($ACC_{50}$), which exhibited a relatively high in vitro ACC-deaminase activity, chitinase activity, auxin production, and P solubilization and more intensive root colonization, was the most efficient isolate under the field conditions. Therefore, these results demonstrated that ACC-deaminase activity is an efficient parameter for the selection of promising PGPR under axenic conditions. However, additional traits of PGPR, including auxin production, chitinase activity, P solubilization, and root colonization, are also important for selecting PGPR as biofertilizers.

• Journal of Microbiology and Biotechnology
• /
• 제20권12호
• /
• pp.1724-1734
• /
• 2010

A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was identified as Rahnella sp. based on its phenotypic features and 16S rRNA gene sequence. The bacterial strain showed the growth characteristics of a cold-adapted psychrotroph, with the multiple plant growth-promoting traits of inorganic and organic phosphate solubilization, 1-aminocyclopropane-1-carboxylate-deaminase activity, ammonia generation, and siderophore production. The strain also produced indole-3-acetic acid, indole-3-acetaldehyde, indole-3-acetamide, indole-3-acetonitrile, indole-3-lactic acid, and indole-3-pyruvic acid in tryptophan-supplemented nutrient broth. Gluconic, citric and isocitric acids were the major organic acids detected during tricalcium phosphate solubilization. A rifampicin-resistant mutant of the strain exhibited high rhizosphere competence without disturbance to the resident microbial populations in pea rhizosphere. Seed bacterization with a charcoal-based inoculum significantly increased growth in barley, chickpea, pea, and maize under the controlled environment. Microplot testing of the inoculum at two different locations in pea also showed significant increase in growth and yield. The attributes of cold-tolerance, high rhizosphere competence, and broad-spectrum plant growth-promoting activity exhibited the potential of Rahnella sp. BIHB 783 for increasing agriculture productivity.

• 한국토양비료학회지
• /
• 제47권3호
• /
• pp.213-216
• /
• 2014

Arsenic is a known hazardous metalloid not only to the animals but also to plants. With high concentrations, it can impede normal plant growth and cause even death of plants at extremely high levels. A known plant response to stress conditions such as toxic levels of metal (loids) is the production of stress ethylene, causing inhibitory effect on root growth in plants. When the effect of various arsenic concentrations was tested to maize plant, the stress ethylene emission proportionately increased with increasing concentration of As(V). The inoculation of two arsenic tolerant bacteria; Pseudomonas grimonti JS126 and Pseudomonas taiwanensis JS238 having respective high and low 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity reduced stress ethylene emission by 59% and 30% in maize grown in arsenic polluted soils. The result suggested the possible use of Pseudomonas grimonti JS126 for phytoremediation of arsenic polluted soils.

• Journal of Microbiology and Biotechnology
• /
• 제18권5호
• /
• pp.958-963
• /
• 2008

A series of experiments were conducted to assess the effectiveness of rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase for growth promotion of peas under drought conditions. Ten rhizobacteria isolated from the rhizosphere of different crops (peas, wheat, and maize) were screened for their growth promoting ability in peas under axenic condition. Three rhizobacterial isolates, Pseudomonas fluorescens biotype G (ACC-5), P. fluorescens (ACC-14), and P. putida biotype A (Q-7), were selected for pot trial on the basis of their source, ACC deaminase activity, root colonization, and growth promoting activity under axenic conditions. Inoculated and uninoculated (control) seeds of pea cultivar 2000 were sown in pots (4 seeds/pot) at different soil moisture levels (25, 50, 75, and 100% of field capacity). Results revealed that decreasing the soil moisture levels from 100 to 25% of field capacity significantly decreased the growth of peas. However, inoculation of peas with rhizobacteria containing ACC deaminase significantly decreased the "drought stress imposed effects" on growth of peas, although with variable efficacy at different moisture levels. At the lowest soil moisture level (25% field capacity), rhizobacterial isolate Pseudomonas fluorescens biotype G (ACC-5) was found to be more promising compared with the other isolates, as it caused maximum increases in fresh weight, dry weight, root length, shoot length, number of leaves per plant, and water use efficiency on fresh and dry weight basis (45, 150, 92, 45, 140, 46, and 147%, respectively) compared with respective uninoculated controls. It is highly likely that rhizobacteria containing ACC deaminase might have decreased the drought-stress induced ethylene in inoculated plants, which resulted in better growth of plants even at low moisture levels. Therefore, inoculation with rhizobacteria containing ACC deaminase could be helpful in eliminating the inhibitory effects of drought stress on the growth of peas.

• 미생물학회지
• /
• 제52권2호
• /
• pp.148-156
• /
• 2016

ACC deaminase 활성이 높은 균주인 Enterobacter ludwigii SJR3를 이용하여 건조와 염분 스트레스 환경에서 토마토 식물의 생장촉진 효과와 스트레스-관련 유전자의 발현을 조사하였다. 4주 키운 토마토 식물에 SJR3 균주 접종 후 건조 스트레스와 염분 스트레스를 처리하면서 1주일 후 식물의 생장을 비교하였다. 건조 스트레스 환경에서는 균주 접종군이 비접종군에 비해 뿌리와 줄기 길이 및 습윤과 건조중량이 각각 37.8, 37.2, 96.8과 146.6% 증가하였고 염분 스트레스 환경에서는 각각 19.2, 25.4, 19.5와 105.8% 증가하였다. 또한 스트레스에 반응하여 토마토 잎에 축적되는 proline의 함량은 크게 늘어나지만 건조와 염분 스트레스 처리 시 비접종 대조군 보다 균주 접종군에서 62.1%와 54.1% 감소되었다. 스트레스 환경에서 자라난 토마토 식물에서 스트레스-관련 유전자들인 ACC oxidase의 유전자 ACO1과 ACO4, ethylene response factor의 유전자 ERF1과 ERF4 등의 상대적인 발현량을 조사하였다. 비 스트레스 대조군과 비교해서 건조와 염분 스트레스 환경의 토마토 식물에서 모든 스트레스-관련 유전자들의 발현이 크게 증가하였으나 SJR3 균주를 접종한 식물의 유전자들은 대부분이 비 스트레스-처리 대조군과 유사한 정도의 유전자 발현량을 나타내었다. 따라서 E. ludwigii SJR3는 식물에서 건조와 염분 스트레스의 완화에 중요한 역할을 하여 작물의 생장을 촉진하고 생산성을 높일 수 있을 것으로 여겨진다.

• Journal of Microbiology and Biotechnology
• /
• 제30권7호
• /
• pp.1027-1036
• /
• 2020

Stipa purpurea is a unique and dominant herbaceous plant species in the alpine steppe and meadows on the Qinghai-Tibet Plateau (QTP). In this work, we analyzed the composition and diversity of the culturable endophytic fungi in S. purpurea according to morphological and molecular identification. Then, we investigated the bioactivities of these fungi against plant pathogenic fungi and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) deaminase activities. A total of 323 fungal isolates were first isolated from S. purpurea, and 33 fungal taxa were identified by internal transcribed spacer primers and grouped into Ascomycota. The diversity of endophytic fungi in S. purpurea was significantly higher in roots as compared to leaves. In addition, more than 40% of the endophytic fungi carried the gene encoding for the ACCD gene. The antibiosis assay demonstrated that 29, 35, 28, 37 and 34 isolates (43.9, 53.1, 42.4, 56.1, and 51.5%) were antagonistic to five plant pathogenic fungi, respectively. Our study provided the first assessment of the diversity of culture-depending endophytic fungi of S. purpurea, demonstrated the potential application of ACCD activity and antifungal activities with potential benefits to the host plant, and contributed to high biomass production and adaptation of S. purpurea to an adverse environment.

• Journal of Microbiology and Biotechnology
• /
• 제19권10호
• /
• pp.1213-1222
• /
• 2009

The search for diverse plant growth-promoting (PGP) diazotrophic bacteria is gaining momentum as efforts are made to exploit them as biofertilizers for various economically important crops. In the present study, 17 diazotrophic strains belonging to eight different genera isolated from rice paddy fields were screened for multiple PGP traits and evaluated for their inoculation effects on canola and rice plants. All of the strains tested positive for 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and production of indole 3-acetic acid (IAA) and ammonia ($NH_3$). Additionally, four of the strains were able to solubilize phosphorus (P), five tested positive for zinc (Zn) solubilization and sulfur (S) oxidation, and eight strains produced siderophores. Based on the presence of multiple PGP traits, 10 strains were selected for inoculation studies. Treatment with Herbaspirillum sp. RFNB26 resulted in maximum root length (54.3%), seedling vigor, and dry biomass in canola, whereas Paenibacillus sp. RFNB4 exhibited the lowest activity under gnotobiotic conditions. However, under pot culture conditions, Paenibacillus sp. RFNB4 significantly increased plant height and dry biomass production by 42.3% and 29.5%, respectively. Canola plants and rhizosphere soils inoculated with Bacillus sp. RFNB6 exhibited significantly higher nitrogenase activity. In greenhouse experiments, Serratia sp. RFNB18 increased rice plant height by 35.1%, Xanthomonas sp. RFNB24 enhanced biomass production by 84.6%, and rice rhizosphere soils inoculated with Herbaspirillum sp. RFNB26 exhibited the highest nitrogenase activity. Our findings indicate that most of the selected strains possess multiple PGP properties that significantly improve the growth parameters of the two plants when tested under controlled conditions.

• 식물병연구
• /
• 제25권3호
• /
• pp.136-142
• /
• 2019

식물 근권과 내생에서 분리한 447 균주 중 식물 생장 촉진특성과 건조 내성이 있는 28 균주를 일차적으로 스크리닝 하였으며, PEG에 의한 인위적 건조 스트레스 조건에서 잎의 상대수분함량과 MDA를 기반으로 GLC02와 KJ40을 선발하였다. 이 두 균주의 효과를 검증하기 위해 밭흙을 사용한 자연 건조에서 식물 포트 검정을 하였으며, 기공전도도와 지상부(줄기와 잎) 무게가 유의하게 증가한 반면 MDA가 감소하였다. 병 억제 효과에서는 GLC02를 처리할 경우 역병의 병진전도가 감소하였으며, KJ40을 처리할 경우 세균성 점무늬병에 대한 억제효과가 있었다. 이를 토대로, GLC02와 KJ40을 처리할 경우 건조 스트레스를 경감시켜주며 식물생장의 증진, 병 억제효과를 유도하여 생물비료의 소재로 사용할 수 있을 것으로 생각된다.