A dynamic rhizosphere interplay between tree roots and soil bacteria under drought stress

Root exudates are thought to play an important role in plant-microbial interactions. In return, soil bacteria can increase the bioavailability of soil minerals, which is typically decreasing in situations such as drought. Here we describe an exudate-driven microbial priming on Cupressus saplings grown outside in forest soil in custom-made rhizotron boxes. A 1-month imposed drought and inoculations with Bacillus subtilis and Pseudomonas stutzeri, bacteria species forest soil isolation, were applied in a factorial design. We revealed that both bacteria associated with Cupressus roots and were more abundant in rhizosphere than in bulk soil. Moreover, root exudation rate increased in inoculated trees under drought with >100 first identified metabolites from Cupressus roots. Among these metabolites, phenolic acid compounds, quinate, and others, were used as carbon and nitrogen sources by both bacterial species. Furthermore, soil phosphorous bioavailability was maintained only in inoculated trees, where a drought-induced decrease in leaf phosphorus and iron was prevented. We provide evidence that changes in exudation rate and composition under drought and bacteria inoculation, support the idea of root recruitment of beneficial bacteria. In turn, trees secreted further carbon source to the rhizosphere and hosted more bacteria, benefited from improved nutrition.

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A dynamic rhizosphere interplay between tree roots and soil bacteria under drought

10.1101/2021.08.24.457490 ◽

2021 ◽

Author(s):

Yaara Oppenheimer-Shaanan ◽

Gilad Jakoby ◽

Maya Starr ◽

Romiel Karliner ◽

Gal Eilon ◽

...

Keyword(s):

Forest Soil ◽

Root Exudates ◽

Soil Bacteria ◽

Bacterial Species ◽

Root Exudation ◽

Pseudomonas Stutzeri ◽

Nitrogen Sources ◽

Microbial Interactions ◽

Tree Roots ◽

Custom Made

Root exudates are thought to play an important role in plant-microbial interactions. In return for nutrition, soil bacteria can increase the bioavailability of soil minerals. However, root exudates typically decrease in situations such as drought, calling into question the efficacy of bacteria-dependent mineral uptake in such stress. Here we tested the hypothesis of exudate-driven microbial priming on Cupressus saplings grown in forest soil in custom-made rhizotron boxes. A 1-month imposed drought and concomitant inoculations with Bacillus subtilis and Pseudomonas stutzeri, bacteria species isolated from the forest soil, were applied using factorial design. Direct bacteria counts and visualization by confocal microscopy showed that both bacteria associated with Cupressus roots. Interestingly, root exudation rates increased with bacteria under drought. Forty four metabolites in exudates were significantly different in concentration between irrigated and drought trees, including phenolic acid compounds and quinate, that were shown to be used as carbon and nitrogen sources by both bacterial species. Importantly, soil phosphorous bioavailability was maintained only in inoculated trees, mitigating drought-induced decrease in leaf phosphorus and iron. Our observations of increased root exudation rate when drought and inoculation regimes were combined, support the idea of root recruitment of beneficial bacteria.

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Optimization of carbon and nitrogen sources for phytase production by Mitsuokella jalaludinii, a new rumen bacterial species

Letters in Applied Microbiology ◽

10.1046/j.1472-765x.2002.01153.x ◽

2002 ◽

Vol 35 (2) ◽

pp. 157-161 ◽

Cited By ~ 17

Author(s):

G.Q. Lan ◽

N. Abdullah ◽

S. Jalaludin ◽

Y.W. Ho

Keyword(s):

Bacterial Species ◽

Nitrogen Sources ◽

Carbon And Nitrogen Sources ◽

Phytase Production ◽

Carbon And Nitrogen ◽

Mitsuokella Jalaludinii

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Isolation, characterization, and molecular identification of soil bacteria showing antibacterial activity against human pathogenic bacteria

Journal of Genetic Engineering and Biotechnology ◽

10.1186/s43141-021-00219-x ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

R. Prashanthi ◽

Shreevatsa G.K. ◽

Krupalini S. ◽

Manoj L.

Keyword(s):

Antibacterial Activity ◽

Soil Bacteria ◽

Pathogenic Bacteria ◽

Nitrogen Sources ◽

Proteinase K ◽

Human Pathogens ◽

E Coli ◽

Carbon And Nitrogen ◽

Culture Filtrates ◽

Proteinase K Treatment

Abstract Background The present study dealt with the screening of soil bacteria with antibacterial activity from different locations in Bangalore, India. Antibiotics play the role of self-defense mechanism for the bacteria and are produced as secondary metabolites to protect themselves from other competitive microorganisms. The need for new antibiotics arose as the pathogenic bacteria acquire resistance to various antibiotics meant for treating human diseases. Given the importance of antibiotics of bacterial origin, standard techniques have been used to isolate and characterize the soil bacteria which showed antibacterial activity. Results The isolated bacteria were tested against human pathogenic bacteria like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae by primary and secondary screening methods. The isolates PR1, PR2, and PR3 were confirmed to have antibacterial activity against S. aureus, E. coli, P. aeruginosa, and K. pneumoniae by both methods. Studies on the effect of filter sterilization, autoclaving, and proteinase K treatment on culture filtrates showed filter sterilization as the best method. The effect of different carbon and nitrogen sources on the antibacterial activity showed that preference by each isolate differed for carbon and nitrogen requirements. The isolates PR1, PR2, and PR3 were identified as Bacillus aryabhattai strain PR-D07, Arthrobacter humicola strain PR-F07, and Neomicrococcus lactis strain PR-F11 through 16S rRNA sequencing. Conclusion Findings from this research work are encouraging and could proceed further to applied aspects. Only 3 bacterial isolates out of 263 isolates from soil samples displayed antibacterial activity against human pathogens S. aureus, E. coli, P. aeruginosa, and K. pneumoniae. They were identified as B. aryabhattai, A. humicola, and N. lactis by 16S rRNA studies and all of them are Gram-positive. Each isolate preferred different carbon and nitrogen sources for their enhanced antibacterial activity. Efficacy of the culture filtrates of these isolates was tested by filter sterilization, autoclaving, and proteinase K treatment. Filter-sterilized culture filtrates showed higher antibacterial activity than other treatments. A comparison of the antibacterial activity of culture filtrates and antibiotic streptomycin produced an inhibition zone of 18.5 mm and 15.5 mm respectively. This is the first report on the antibacterial activity of all the 3 bacterial strains (B. aryabhattai strain PR-D07, A. humicola strain PR-F07, and N. lactis strain PR-F11), against all the human pathogens, mentioned earlier. It is also found that the antibiotic factor is proteinaceous as proteinase K considerably reduced the antibacterial activity of the culture filtrates. With the above significant results, these 3 bacteria are considered to be promising candidates for the isolation of new antibacterial agents.

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Tetrapisispora taiwanensis sp. nov. and Tetrapisispora pingtungensis sp. nov., two ascosporogenous yeast species isolated from soil

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijs.0.051227-0 ◽

2013 ◽

Vol 63 (Pt_6) ◽

pp. 2351-2355

Author(s):

Shan-Fu Chen ◽

Shih Feng Lo ◽

Chin-Feng Chang ◽

Ching-Fu Lee

Keyword(s):

Forest Soil ◽

Type Strain ◽

Yeast Species ◽

Large Subunit ◽

Morphological Characteristics ◽

Nitrogen Sources ◽

Rrna Gene ◽

Carbon And Nitrogen ◽

Lsu Rrna Gene ◽

Ascosporogenous Yeast

Two novel yeast species, Tetrapisispora taiwanensis sp. nov. and Tetrapisispora pingtungensis sp. nov., belonging to the Saccharomycetaceae within the Saccharomycetales, are proposed to accommodate six strains isolated from samples of Taiwanese forest soil between 2005 and 2010. Sequence analysis of the internal transcribed spacer (ITS) and the D1/D2 domains of the large-subunit (LSU) rRNA gene revealed that the two species are phylogenetically closely related to species of the genus Tetrapisispora. Moreover, the assimilation spectrum of carbon and nitrogen sources and morphological characteristics are very similar to those of other Tetrapisispora species. The molecular, morphological and physiological characteristics described above indicate that these two species should be classified as members of the genus Tetrapisispora. The two species can be differentiated from each other and from other Tetrapisispora species based on their LSU D1/D2 rRNA gene and ITS sequences. Thus, the two species could be regarded as novel species of the genus Tetrapisispora, and the names Tetrapisispora taiwanensis sp. nov. (type strain SJ6S04T = CBS 10586T = NBRC 102652T = BCRC 23090T) and Tetrapisispora pingtungensis sp. nov. (type strain NC2S06T = CBS 12780T = BCRC 23409T) are proposed. The type strains of the two species were isolated from forest soil in Leinhuatsu Park, Nantou, in 2006 and from Hungchun, Pingtung, in 2009, respectively.

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THE STUDY OF ETHANOL PRODUCTION BY NEW STRAIN OF YEASTS "HANSENIASPORA OPUNTIAE MK 460485", INVESTIGATION OF ITS ETHANOL PRODUCTION IN PRESENCE OF DIFFERENT CARBON AND NITROGEN SOURCES, AND OPTIMAL CONDITIONS

Journal of Critical Reviews ◽

10.31838/jcr.07.04.94 ◽

2020 ◽

Vol 7 (04) ◽

Keyword(s):

Ethanol Production ◽

Nitrogen Sources ◽

Optimal Conditions ◽

Carbon And Nitrogen Sources ◽

Carbon And Nitrogen

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A highly thermotolerant laccase produced by Cerrena unicolor strain CGMCC 5.1011 for complete and stable malachite green decolorization

AMB Express ◽

10.1186/s13568-020-01118-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yanhua Yao ◽

Guimei Zhou ◽

Yonghui Lin ◽

Xinqi Xu ◽

Jie Yang

Keyword(s):

Malachite Green ◽

Fermentation Broth ◽

Nitrogen Sources ◽

Life Time ◽

Industrial Applications ◽

Dynamics Simulation ◽

Carbon And Nitrogen ◽

Cdna Sequences ◽

Cerrena Unicolor ◽

Future Work

Abstract Laccases are a class of multi-copper oxidases with important industrial values. A thermotolerant laccase produced by a basidiomycete fungal strain Cerrena unicolor CGMCC 5.1011 was studied. With glycerin and peptone as the carbon and nitrogen sources, respectively, a maximal laccase activity of 121.7 U/mL was attained after cultivation in the shaking flask for 15 days. Transcriptomics analysis revealed an expressed laccase gene family of 12 members in C. unicolor strain CGMCC 5.1011, and the gene and cDNA sequences were cloned. A glycosylated laccase was purified from the fermentation broth of Cerrena unicolor CGMCC 5.1011 and corresponded to Lac2 based on MALDI-TOF MS/MS identification. Lac2 was stable at pH 5.0 and above, and was resistant to organic solvents. Lac2 displayed remarkable thermostability, with half-life time of 1.67 h at 70 ºC. Consistently, Lac2 was able to completely decolorize malachite green (MG) at high temperatures, whereas Lac7 from Cerrena sp. HYB07 resulted in accumulation of colored MG transformation intermediates. Molecular dynamics simulation of Lac2 was conducted, and possible mechanisms underlying Lac2 thermostability were discussed. The robustness of C. unicolor CGMCC 5.1011 laccase would not only be useful for industrial applications, but also provide a template for future work to develop thermostable laccases.

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