Isolation, Characterization, and Use for Plant Growth Promotion under Salt Stress, of ACC Deaminase-Producing Halotolerant Bacteria Derived from Coastal Soil

Department of Agricultural Chemistry, Chungbuk National University, Cheongju, Chungbuk, 361-763, Korea.
Journal of Microbiology and Biotechnology (Impact Factor: 1.53). 11/2010; 20(11):1577-84.
Source: PubMed


In total, 140 halotolerant bacterial strains were isolated from both the soil of barren fields and the rhizosphere of six naturally growing halophytic plants in the vicinity of the Yellow Sea, near the city of Incheon in the Republic of Korea. All of these strains were characterized for multiple plant growth promoting traits, such as the production of indole acetic acid (IAA), nitrogen fixation, phosphorus (P) and zinc (Zn) solubilization, thiosulfate (S2O3) oxidation, the production of ammonia (NH3), and the production of extracellular hydrolytic enzymes such as protease, chitinase, pectinase, cellulase, and lipase under in vitro conditions. From the original 140 strains tested, on the basis of the latter tests for plant growth promotional activity, 36 were selected for further examination. These 36 halotolerant bacterial strains were then tested for 1- aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Twenty-five of these were found to be positive, and to be exhibiting significantly varying levels of activity. 16S rRNA gene sequencing analyses of the 36 halotolerant strains showed that they belong to 10 different bacterial genera: Bacillus, Brevibacterium, Planococcus, Zhihengliuella, Halomonas, Exiguobacterium, Oceanimonas, Corynebacterium, Arthrobacter, and Micrococcus. Inoculation of the 14 halotolerant bacterial strains to ameliorate salt stress (150 mM NaCl) in canola plants produced an increase in root length of between 5.2% and 47.8%, and dry weight of between 16.2% and 43%, in comparison with the uninoculated positive controls. In particular, three of the bacteria, Brevibacterium epidermidis RS15, Micrococcus yunnanensis RS222, and Bacillus aryabhattai RS341, all showed more than 40% increase in root elongation and dry weight when compared with uninoculated saltstressed canola seedlings. These results indicate that certain halotolerant bacteria, isolated from coastal soils, have a real potential to enhance plant growth under saline stress, through the reduction of ethylene production via ACC deaminase activity.

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    • "Application of maize increased also the relative abundance of phylotypes belonging to the genus Arthrobacter. Arthrobacter was described by Semenov et al. (2012) as a primary sequestrator with known cellulolytic activity (Siddikee et al., 2010). Proteobacteria whose population can fluctuate 'opportunistically', are well known to respond readily to labile C sources (Fierer et al., 2007). "
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    ABSTRACT: Agricultural practices affect the bacterial community structure in soil. It was hypothesized that agricultural practices would also affect the bacteria involved in the degradation of crop residue. Soil was sampled from four different agricultural practices, i.e. conventional agriculture on the flat or on beds, or conservation agriculture on the flat or on beds. Cultivating crops on the flat is done traditionally, but cultivating crops on beds was introduced so as to avoid water logging during the rainy season and its potential negative effect on yields. Soil from these four treatments was amended in the laboratory with maize residue (Zea mays L.) or its neutral detergent fibre (NDF) fraction, mostly consisting of (hemi) cellulose, and incubated aerobically for 14 days. Maize residue was applied to soil as it is left in the field in conservation agriculture and NDF was added to study which bacteria were favoured by application of (hemi) cellulose. Soil was incubated aerobically while the carbon mineralization and the bacterial population were monitored. On the one hand, the relative abundance of phylotypes belonging to bacterial groups that preferred low nutrient environments was higher in soil with conservation agriculture (e.g. Acidobacteria 17.6%, Planctomycetes 1.7% and Verrucomicrobia 1.5%) compared to conventional practices (Acidobacteria 11.8%, Planctomycetes 0.9% and Verrucomicrobia 0.4%). On the other hand, the relative abundance of phylotypes belonging to bacterial groups that preferred nutrient rich environments, such as Actinobacteria, showed an opposite trend. It was 11.9% in conservation agriculture and 16.2% in conventional practices. The relative abundance of Arthrobacter (Actinobacteria) and Bacillales more than doubled when maize residue was applied to soil compared to the unamended soil and that of Actinomycetales when maize or NDF was applied. Application of organic material reduced the relative abundance of a wide range of bacterial groups, e.g. Acidobacteria, Bacteroidetes, Planctomycetes and Verrucomicrobia. It was found that application of organic material favoured the same bacterial groups that were more abundant in the soil cultivated conventionally while it reduced those that were favoured in conservation agriculture
    Applied Soil Ecology 06/2015; 90. DOI:10.1016/j.apsoil.2015.01.010 · 2.64 Impact Factor
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    • "Streptomyces are salt-tolerant bacteria, and a maximum tolerance of up to 13% NaCl has been reported previously (Tresner et al. 1968). Halotolerant ACC deaminase-producing bacteria have been reported to enhance the growth of canola and Capsicum annum plants (Siddikee et al. 2010, 2011). Salt stress was reported to affect plant productivity by reducing the photosynthetic efficiency (Flors et al. 2007). "
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    ABSTRACT: Aim: To identify an actinobacterial strain that can promote growth and alleviate salinity stress in tomato plants. Methods and Results: Actinobacteria were isolated from agricultural soil and screened for ACC deaminase activity, production of indole acetic acid (IAA), solubilization of tricalcium phosphate, and sodium chloride (NaCl) salinity tolerance. Among the several strains tested one strain designated PGPA39 exhibited higher IAA production, and phosphate solubilization in addition to ACC deaminase activity, and tolerance to 1 M NaCl. Strain PGPA39 was identified as a Streptomyces strain based on 16S rDNA sequence and designated Streptomyces sp. strain PGPA39. It promoted the growth of Arabidopsis seedlings in vitro as evidenced by a significant increase in plant biomass, and number of lateral roots. Salinity stress alleviating activity of PGPA39 was evaluated using “Micro Tom” tomato plants with 180 mM NaCl stress under gnotobiotic condition. A significant increase in plant biomass and chlorophyll content, and a reduction in leaf proline content were observed in PGPA39-inoculated tomato plants under salt stress compared to control and salt stressed non-inoculated plants. Conclusion: Streptomyces sp. strain PGPA39 alleviated salt stress and promoted the growth of tomato plants. Significance and Impact of the Study: This study shows the potential of Streptomyces sp. strain PGPA39 in alleviating salinity stress in tomato plants and could be utilized for stress alleviation in crop plants under field conditions.
    Journal of Applied Microbiology 09/2014; DOI:10.1111/jam.12563 · 2.48 Impact Factor
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    • "Whereas inoculation with Pseudomonas taiwanensis JS238 with comparatively less enzyme activity could reduce ethylene production in maize roots at a low level of 30%. The enzyme ACC deaminase (E.C. cleaves ACC, the immediate precursor of ethylene in plants, to form ammonia and α -ketobutyrate, thus lowering stress ethylene level in plants (Glick et al., 2007; Siddikee et al., 2010). The ACC deaminase producing bacteria in the rhizosphere serves as a sink for excess ACC produced in the plants during stress conditions leading to unhindered root growth (Arshad et al., 2007). "
    08/2014; 47(3). DOI:10.7745/KJSSF.2014.47.3.213
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