Research

9 pages, 1404 KiB

Open AccessArticle

Purification and Characterization of a Novel Antifungal Flagellin Protein from Endophyte Bacillus methylotrophicus NJ13 against Ilyonectria robusta

by Yun Jiang, Chao Ran, Lin Chen, Wang Yin, Yang Liu, Changqing Chen and Jie Gao

Microorganisms 2019, 7(12), 605; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7120605 - 22 Nov 2019

Cited by 12 | Viewed by 2702

Abstract

Endophyte Bacillus methylotrophicus NJ13 was isolated from Panax ginseng. Its sterile fermentation liquid showed a significant inhibitory effect against Ilyonectria robusta, causing the rusty root rot of P. ginseng and P. quinquefolius. The antifungal protein was obtained after precipitation by [...] Read more.

Endophyte Bacillus methylotrophicus NJ13 was isolated from Panax ginseng. Its sterile fermentation liquid showed a significant inhibitory effect against Ilyonectria robusta, causing the rusty root rot of P. ginseng and P. quinquefolius. The antifungal protein was obtained after precipitation by 20% saturated ammonium sulfate, desalted by Sephadex G-25, weak anion exchange chromatography, and gel filtration chromatography. SDS-PAGE showed that the purified protein was approximately 29 KDa. The antifungal protein after desalting was not resistant to temperatures higher than 100 °C, resistant to acid conditions, and did not tolerate organic solvents and protease K. The amino acid sequence of purified antifungal protein had an identity of 76% to flagellin from Bacillus velezensis. The isoelectric point of the protein was 4.97 and its molecular mass was 27 KDa. Therefore, a specific primer G1 was designed based on the flagellin gene sequence, and a 770 bp gene sequence was cloned in NJ13 genomic DNA, which shared the same size of flagellin. There were ten base differences between the gene sequences of flagellin and the cloned gene, however, the amino acid sequence encoded by the cloned gene was identical to the flagellin. In conclusion, the antifungal protein produced by biocontrol agent NJ13 contained a flagellin protein. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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17 pages, 3894 KiB

Open AccessArticle

Root-Associated Fungal Communities in Two Populations of the Fully Mycoheterotrophic Plant Arachnitis uniflora Phil. (Corsiaceae) in Southern Chile

by Hector Herrera, Javiera Soto, Luz E. de Bashan, Inmaculada Sampedro and Cesar Arriagada

Microorganisms 2019, 7(12), 586; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7120586 - 20 Nov 2019

Cited by 10 | Viewed by 2869

Abstract

The microbiological interactions of the roots of non-photosynthetic plants in South America have been scarcely explored. This study analyzes culturable fungal diversity associated with the mycoheterotrophic plant Arachnitis uniflora Phil. (Corsiaceae) in southern Chile, growing in two different understoreys of native (Nothofagus [...] Read more.

The microbiological interactions of the roots of non-photosynthetic plants in South America have been scarcely explored. This study analyzes culturable fungal diversity associated with the mycoheterotrophic plant Arachnitis uniflora Phil. (Corsiaceae) in southern Chile, growing in two different understoreys of native (Nothofagus-dominated) and mixed forest (native, Cupressus sempervirens, and Pinus radiata). Rhizospheric and endophytic fungi were isolated, cultured, and purified to identify microorganisms associated with A. uniflora roots. We showed the different fungi associated with the plant, and that these distributions are influenced by the sampling site. We isolated 410 fungal strains (144 endophytic and 266 from the rhizosphere). We identified 13 operative taxonomical units from plants sampled in the mixed forest, while 15 were from the native forest. Rhizospheric microorganisms were mainly related to Penicillium spp., whereas some pathogenic and saprophytic strains were more frequent inside the roots. Our results have also shown that the fungal strains are weak for phosphate solubilization, but other pathways such as organic acid exudation and indole acetic acid production can be considered as major mechanisms to stimulate plant growth. Our results point to new fungal associates of A. uniflora plants reported in Andean ecosystems, identifying new beneficial endophytic fungi associated with roots of this fully mycoheterotrophic plant. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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18 pages, 1037 KiB

Open AccessArticle

Isolation, Screening, and Characterization of Plant-Growth-Promoting Bacteria from Durum Wheat Rhizosphere to Improve N and P Nutrient Use Efficiency

by Nilde Antonella Di Benedetto, Daniela Campaniello, Antonio Bevilacqua, Mariagrazia Pia Cataldi, Milena Sinigaglia, Zina Flagella and Maria Rosaria Corbo

Microorganisms 2019, 7(11), 541; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7110541 - 08 Nov 2019

Cited by 27 | Viewed by 3922

Abstract

The main goal of this paper was to select promising microorganisms which could potentially act as plant-growth-promoting bacteria (PGPB) for durum wheat of Foggia County. At this scope, a new statistical framework, based on multivariate analyses and the evaluation of the statistical distribution [...] Read more.

The main goal of this paper was to select promising microorganisms which could potentially act as plant-growth-promoting bacteria (PGPB) for durum wheat of Foggia County. At this scope, a new statistical framework, based on multivariate analyses and the evaluation of the statistical distribution of each trait, was used. Four hundred and seventy-four isolates were isolated from the rhizosphere of durum wheat in Foggia County and preliminarily screened as a function of four target indices (ammonium production, siderophores production, P-solubilization, and nitrification). After this step, the number of strains was reduced and the remaining isolates were tested through a quantitative approach, to assess the production of IAA (indole acetic acid), P-mineralization, and nitrification. In this second step, the cut-off was based on the whole population trend by evaluating for each trait the medians and quartiles. As a result, 16 promising isolates were selected and identified by 16S rDNA sequencing (Bacillus, Pseudomonas, Stenotrophomonas, and Lysinibacillus). The last step of this research was a preliminary validation in a growth chamber on eight strains. As screening and simple indices, two quantitative measures were chosen. The main result was the selection of at least three isolates (6P, 20P, and 25A) for a future field validation. They increased biomass and height by respectively 50% and 25%. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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23 pages, 2474 KiB

Open AccessArticle

Mediterranean Native Leguminous Plants: A Reservoir of Endophytic Bacteria with Potential to Enhance Chickpea Growth under Stress Conditions

by Clarisse Brígido, Esther Menéndez, Ana Paço, Bernard R. Glick, Anabela Belo, Maria R. Félix, Solange Oliveira and Mário Carvalho

Microorganisms 2019, 7(10), 392; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7100392 - 25 Sep 2019

Cited by 17 | Viewed by 4068

Abstract

Bacterial endophytes, a subset of a plant’s microbiota, can facilitate plant growth by a number of different mechanisms. The aims of this study were to assess the diversity and functionality of endophytic bacterial strains from internal root tissues of native legume species grown [...] Read more.

Bacterial endophytes, a subset of a plant’s microbiota, can facilitate plant growth by a number of different mechanisms. The aims of this study were to assess the diversity and functionality of endophytic bacterial strains from internal root tissues of native legume species grown in two distinct sites in South of Portugal and to evaluate their ability to promote plant growth. Here, 122 endophytic bacterial isolates were obtained from 12 different native legume species. Most of these bacteria possess at least one of the plant growth-promoting features tested in vitro, with indole acetic acid production being the most common feature among the isolates followed by the production of siderophores and inorganic phosphate solubilization. The results of in planta experiments revealed that co-inoculation of chickpea plants with specific endophytic bacteria along with N₂-fixing symbionts significantly improved the total biomass of chickpea plants, in particular when these plants were grown under saline conditions. Altogether, this study revealed that Mediterranean native legume species are a reservoir of plant growth-promoting bacteria, that are also tolerant to salinity and to toxic levels of Mn. Thus, these bacterial endophytes are well adapted to common constraints present in soils of this region which constitutes important factors to consider in the development of bacterial inoculants for stressful conditions in the Mediterranean region. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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21 pages, 2104 KiB

Open AccessArticle

Root Bacteria Recruited by Phragmites australis in Constructed Wetlands Have the Potential to Enhance Azo-Dye Phytodepuration

by Valentina Riva, Francesca Mapelli, Evdokia Syranidou, Elena Crotti, Redouane Choukrallah, Nicolas Kalogerakis and Sara Borin

Microorganisms 2019, 7(10), 384; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7100384 - 24 Sep 2019

Cited by 29 | Viewed by 4077

Abstract

The microbiome associated with plants used in phytodepuration systems can boost plant growth and services, especially in ecosystems dealing with recalcitrant compounds, hardly removed via traditional wastewater (WW) treatments, such as azo-dyes used in textile industry. In this context, we aimed to study [...] Read more.

The microbiome associated with plants used in phytodepuration systems can boost plant growth and services, especially in ecosystems dealing with recalcitrant compounds, hardly removed via traditional wastewater (WW) treatments, such as azo-dyes used in textile industry. In this context, we aimed to study the cultivable microbiome selected by Phragmites australis plants in a Constructed Wetland (CW) in Morocco, in order to obtain candidate inoculants for the phytodepuration of azo-dye contaminated WW. A collection of 152 rhizospheric and endophytic bacteria was established. The strains were phylogenetically identified and characterized for traits of interest in the phytodepuration context. All strains showed Plant Growth Promotion potential in vitro and 67% of them significantly improved the growth of a model plant in vivo compared to the non bacterized control plants. Moreover, most of the isolates were able to grow in presence of several model micropollutants typically found in WW, indicating their potential use in phytodepuration of a wide spectrum of effluents. The six most promising strains of the collection were tested in CW microcosms alone or as consortium: the consortium and two single inocula demonstrated to significantly increase the removal of the model azo-dye Reactive Black 5 compared to the non bacterized controls. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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25 pages, 6804 KiB

Open AccessArticle

Genetic Screening and Expression Analysis of Psychrophilic Bacillus spp. Reveal Their Potential to Alleviate Cold Stress and Modulate Phytohormones in Wheat

by Muhammad Zubair, Alvina Hanif, Ayaz Farzand, Taha Majid Mahmood Sheikh, Abdur Rashid Khan, Muhammad Suleman, Muhammad Ayaz and Xuewen Gao

Microorganisms 2019, 7(9), 337; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7090337 - 10 Sep 2019

Cited by 72 | Viewed by 5906

Abstract

Abiotic stress in plants pose a major threat to cereal crop production worldwide and cold stress is also notorious for causing a decrease in plant growth and yield in wheat. The present study was designed to alleviate cold stress on plants by inoculating [...] Read more.

Abiotic stress in plants pose a major threat to cereal crop production worldwide and cold stress is also notorious for causing a decrease in plant growth and yield in wheat. The present study was designed to alleviate cold stress on plants by inoculating psychrophilic PGPR bacteria belonging to Bacillus genera isolated from extreme rhizospheric environments of Qinghai-Tibetan plateau. The genetic screening of psychrophilic Bacillus spp. CJCL2, RJGP41 and temperate B. velezensis FZB42 revealed presence of genetic features corresponding to cold stress response, membrane transport, signal transduction and osmotic regulation. Subsequently, the time frame study for the expression of genes involved in these pathways was also significantly higher in psychrophilic strains as analyzed through qPCR analysis at 4 ℃. The inoculated cold tolerant Bacillus strains also aided in inducing stress response in wheat by regulating abscisic acid, lipid peroxidation and proline accumulation pathways in a beneficial manner. Moreover, during comparative analysis of growth promotion in wheat all three Bacillus strains showed significant results at 25 ℃. Whereas, psychrophilic Bacillus strains CJCL2 and RJGP41 were able to positively regulate the expression of phytohormones leading to significant improvement in plant growth under cold stress. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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14 pages, 3359 KiB

Open AccessArticle

Arbuscular Mycorrhiza Enhances Biomass Production and Salt Tolerance of Sweet Sorghum

by Fayuan Wang, Yuhuan Sun and Zhaoyong Shi

Microorganisms 2019, 7(9), 289; https://doi.org/10.3390/microorganisms7090289 - 23 Aug 2019

Cited by 39 | Viewed by 3515

Abstract

Arbuscular mycorrhizal (AM) fungi (AMF) are widely known to form a symbiosis with most higher plants and enhance plant adaptation to a series of environmental stresses. Sweet sorghum (Sorghum bicolor (L.) Moench) is considered a promising alternative feedstock for bioalcohol production because [...] Read more.

Arbuscular mycorrhizal (AM) fungi (AMF) are widely known to form a symbiosis with most higher plants and enhance plant adaptation to a series of environmental stresses. Sweet sorghum (Sorghum bicolor (L.) Moench) is considered a promising alternative feedstock for bioalcohol production because of its sugar-rich stalk and high biomass. However, little is known of AMF benefit for biomass production and salt tolerance of sweet sorghum. Here, we investigated the effects of Acaulospora mellea ZZ on growth and salt tolerance in two sweet sorghum cultivars (Liaotian5 and Yajin2) under different NaCl addition levels (0, 0.5, 1, 2, and 3 g NaCl/kg soil). Results showed AMF colonized the two cultivars well under all NaCl addition levels. NaCl addition increased mycorrhizal colonization rates in Yajin2, but the effects on Liaotian5 ranged from stimulatory at 0.5 and 1 g/kg to insignificant at 2 g/kg, and even inhibitory at 3 g/kg. High NaCl addition levels produced negative effects on both AM and non-AM plants, leading to lower biomass production, poorer mineral nutrition (N, P, K), higher Na⁺ uptake, and lower soluble sugar content in leaves. Compared with non-AM plants, AM plants of both cultivars had improved plant biomass and mineral uptake, as well as higher K⁺/Na⁺ ratio, but only Yajin2 plants had a low shoot/root Na ratio. AM inoculation increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and soluble sugar content in leaves. Overall, both cultivars benefited from mycorrhization, and Yajin2 with less salt tolerance showed higher mycorrhizal response. In conclusion, AMF could help to alleviate the negative effects caused by salinity, and thus showed potential in biomass production of sweet sorghum in saline soil. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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21 pages, 7783 KiB

Open AccessArticle

Diversity and Co-Occurrence Patterns of Soil Bacterial and Fungal Communities of Chinese Cordyceps Habitats at Shergyla Mountain, Tibet: Implications for the Occurrence

by Jun-Li Shao, Bei Lai, Wei Jiang, Jia-Ting Wang, Yue-Hui Hong, Fu-Bin Chen, Shao-Qing Tan and Lian-Xian Guo

Microorganisms 2019, 7(9), 284; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7090284 - 22 Aug 2019

Cited by 17 | Viewed by 3538

Abstract

Chinese Cordyceps is a well-known medicinal larva-fungus symbiote distributed in the Qinghai-Tibetan Plateau and adjacent areas. Previous studies have involved its artificial cultivation but commercial cultivation is difficult to perform because the crucial factors triggering the occurrence of Chinese Cordyceps are not quite [...] Read more.

Chinese Cordyceps is a well-known medicinal larva-fungus symbiote distributed in the Qinghai-Tibetan Plateau and adjacent areas. Previous studies have involved its artificial cultivation but commercial cultivation is difficult to perform because the crucial factors triggering the occurrence of Chinese Cordyceps are not quite clear. The occurrence of Chinese Cordyceps is greatly affected by the soil environment, including the soil’s physicochemical and microecological properties. In this study, the effects of these soil properties on the occurrence of Chinese Cordyceps were investigated. The results show that the physicochemical properties, including easily oxidizable organic carbon (EOC), soil organic carbon (SOC), humic acid carbon (HAC), humin carbon (HMC), and pH, might be negatively related to the occurrence of Chinese Cordyceps, and soil water content (SWC) might be positively related. Several soil physicochemical parameters (pH, SOC, HMC, HAC, available potassium (APO), available phosphorus (APH), microbial biomass carbon (MBC), and the ratio of NH₄⁺ to NO₃⁻ (NH₄⁺/NO₃⁻)) and microbial properties interact and mix together, which might affect the occurrence of Chinese Cordyceps. Soil microbial community structure was also a possible factor, and a low level of bacterial and fungal diversity was suitable for the occurrence of Chinese Cordyceps. The intra-kingdom network revealed that a closer correlation of the bacterial community might help the occurrence of Chinese Cordyceps, while a closer correlation of the fungal community might suppress it. The inter-kingdom network revealed that the occurrence rate of Chinese Cordyceps might be negatively correlated with the stability of the correlation state of the soil habitat. In conclusion, this study shows that soil physicochemical properties and microbial communities could be greatly related with the occurrence of Chinese Cordyceps. In addition, soil physicochemical properties, the level of bacterial and fungal diversity, and correlations of bacterial and fungal communities should be controlled to a certain level to increase the production of Chinese Cordyceps in artificial cultivation. Full article

(This article belongs to the Special Issue Probiotic Microorganism in Plants, Rhizosphere and Soil)

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