Endophytic Actinobacteria: Nitrogen Fixation, Phytohormone Production, and Antibiosis

Swarnalakshmi, Karivaradharajan; Senthilkumar, M.; Ramakrishnan, B.

doi:10.1007/978-981-10-0707-1_8

Cited by 19 publications

(13 citation statements)

References 200 publications

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“…Moreover, the genomes of Actinobacteria possess genes for nitrogen fixation and production of antibiotics (Fig. 7 ) which may enhance their fitness and competing to acquire carbon sources and protect against environmental perturbations [ 25 , 26 ].…”

Section: Discussionmentioning

confidence: 99%

“…Physiologically, Actinobacteria communities harbor the complete catalog of hydrolytic enzymes (e.g., β -glucosidase, cellobiohydrolase, ligninase, acetyl xylan esterase, arabinofuranosidase, and/or their assembled supramolecular cellulosomes) needed for plant residue decomposition [ 11 , 17 , 23 ]. In addition, the high C:N ratio of plant residues limits the available N for microorganisms to reproduce [ 24 ], while the nitrogen fixation ability of Actinobacteria may increase N availability during microbial-driven plant residue decomposition [ 25 ]. Ecologically, Actinobacteria can suppress competitors by synthesizing antibiotics [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

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Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils

et al. 2021

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Background Microbial-driven decomposition of plant residues is integral to carbon sequestration in terrestrial ecosystems. Actinobacteria, one of the most widely distributed bacterial phyla in soils, are known for their ability to degrade plant residues in vitro. However, their in situ importance and specific activity across contrasting ecological environments are not known. Here, we conducted three field experiments with buried straw in combination with microcosm experiments with 13C-straw in paddy soils under different soil fertility levels to reveal the ecophysiological roles of Actinobacteria in plant residue decomposition. Results While accounting for only 4.6% of the total bacterial abundance, the Actinobacteria encoded 16% of total abundance of carbohydrate-active enzymes (CAZymes). The taxonomic and functional compositions of the Actinobacteria were, surprisingly, relatively stable during straw decomposition. Slopes of linear regression models between straw chemical composition and Actinobacterial traits were flatter than those for other taxonomic groups at both local and regional scales due to holding genes encoding for full set of CAZymes, nitrogenases, and antibiotic synthetases. Ecological co-occurrence network and 13C-based metagenomic analyses both indicated that their importance for straw degradation increased in less fertile soils, as both links between Actinobacteria and other community members and relative abundances of their functional genes increased with decreasing soil fertility. Conclusions This study provided DNA-based evidence that non-dominant Actinobacteria plays a key ecophysiological role in plant residue decomposition as their members possess high proportions of CAZymes and as a group maintain a relatively stable presence during plant residue decomposition both in terms of taxonomic composition and functional roles. Their importance for decomposition was more pronounced in less fertile soils where their possession functional genes and interspecies interactions stood out more. Our work provides new ecophysiological angles for the understanding of the importance of Actinobacteria in global carbon cycling.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils

et al. 2021

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“…Bacterial-based BSs are formulations of microbial-derived compounds and diverse groups of plant growth-promoting Rhizobacteria (PGPR) and other beneficial bacteria (e.g., Actinomycetes ) that promote root development, growth, and stress tolerance [ 2 , 29 , 39 , 98 ]. The bacterial taxa commonly used as microbial BSs include Acetobacter , Agrobacterium , Azospirillum , Azotobacter , Bacillus , Burkholderia , Enterobacter , Frankia , Pseudomonas , Rhizobia , Serratia , and Streptomyces [ 39 , 75 , 98 , 99 , 100 , 101 , 102 , 103 , 104 ]. Applications of microbial BSs were reported to alter several metabolic processes, influence ion homeostasis, enhance water holding capacity, and strengthen antioxidant defense mechanisms, thus delivering better plant growth and resilience [ 29 , 51 , 98 , 99 ].…”

Section: Microbial and Non-microbial Biostimulants: Action/mechanisms And Biostimulatory Effects On Plantsmentioning

confidence: 99%

Harnessing Synergistic Biostimulatory Processes: A Plausible Approach for Enhanced Crop Growth and Resilience in Organic Farming

Sani

Yong

2021

Biology

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Demand for organically grown food crops is rising substantially annually owing to their contributions to human health. However, organic farm production is still generally lower compared to conventional farming. Nutrient availability, content consistency, uptake, assimilation, and crop responses to various stresses were reported as critical yield-limiting factors in many organic farming systems. In recent years, plant biostimulants (BSs) have gained much interest from researchers and growers, and with the objective of integrating these products to enhance nutrient use efficiency (NUE), crop performance, and delivering better stress resilience in organic-related farming. This review gave an overview of direct and indirect mechanisms of microbial and non-microbial BSs in enhancing plant nutrient uptake, physiological status, productivity, resilience to various stressors, and soil-microbe-plant interactions. BSs offer a promising, innovative and sustainable strategy to supplement and replace agrochemicals in the near future. With greater mechanistic clarity, designing purposeful combinations of microbial and non-microbial BSs that would interact synergistically and deliver desired outcomes in terms of acceptable yield and high-quality products sustainably will be pivotal. Understanding these mechanisms will improve the next generation of novel and well-characterized BSs, combining microbial and non-microbial BSs strategically with specific desired synergistic bio-stimulatory action, to deliver enhanced plant growth, yield, quality, and resilience consistently in organic-related cultivation.

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“…Otras bacterias especializadas son las fijadoras de nitrógeno, que junto con las cianobacterias y las actinobacterias, forman un grupo único de microorganismos capaces de fijar este elemento químico además de producir metabolitos secundarios (Swarnalakshmi, Senthilkumar & Ramakrishnan, 2016). Estos microorganismos primero reducen el nitrógeno hasta una forma utilizable mediante la fijación biológica de nitrógeno (FBN), y después lo combinan o fijan en la forma de iones amonio.…”

Section: Bacterias Endófitasunclassified

Bacterias y hongos endófitos de la familia Cactaceae y sus aplicaciones

et al. 2021

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Las especies de la familia Cactaceae habitan en zonas con altas temperaturas, escasez de agua y suelos con déficit de nutrimentos. Esto es el resultado de procesos complejos como adaptaciones fisiológicas y físicas, además de la coevolución con microorganismos endófitos que habitan en los tejidos vegetales con relevante importancia para las plantas, porfacilitar su establecimiento en estratos rocosos, ayudar a la fijación de nitrógeno atmosférico y fósforo a través de bacterias, así como una acción antimicrobiana por parte de los hongos. Los estudios sobre bioprospección de endófitos en las cactáceas aún son escasos, por lo que este trabajo compila la literatura científica sobre bacterias y hongos endófitos en cactus disponible en las bases de datos Dialnet, DOAJ, EBSCO, Google académico, iSEEK, Redalyc, REDIB, Science Direct, SciFinder, SciELO, Springer, Web of Science y Wiley Online Library. La revisión dio como resultado 22 trabajos publicados en un periodo de 33 años, de los que solamente el 36% analiza su bioactividad. Se destaca el uso de los endófitos en la biotecnología, principalmente para beneficio social (fines agrícolas y médicos), así como de conservación.

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Endophytic Actinobacteria: Nitrogen Fixation, Phytohormone Production, and Antibiosis

Cited by 19 publications

References 200 publications

Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils

Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils

Harnessing Synergistic Biostimulatory Processes: A Plausible Approach for Enhanced Crop Growth and Resilience in Organic Farming

Bacterias y hongos endófitos de la familia Cactaceae y sus aplicaciones

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