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Biology Letters Mar 2022Declining food production in African agroecosystems is attributable to changes in weather patterns, soil infertility and limited farming inputs. The exploitation of...
Declining food production in African agroecosystems is attributable to changes in weather patterns, soil infertility and limited farming inputs. The exploitation of plant growth-promoting soil microbes could remedy these problems. Such microbes include ; free-living, nitrogen-fixing bacteria, which confer stress tolerance, avail phytohormones and aid in soil bioremediation. Here, we aimed to isolate, characterize and determine the biodiversity of native isolates from soils in semi-arid Eastern Kenya. Isolation was conducted on nitrogen-free Ashby's agar and the morphological, biochemical and molecular attributes evaluated. The isolates were sequenced using DNA amplicons of 27F and 1492R primers of the 16S rRNA gene loci. The Basic Local Alignment Search Tool (BLASTn) analysis of their sequences revealed the presence of three main species viz., and . Kitui County recorded the highest number of recovered isolates (45.4%) and lowest diversity index (0.8761). Tharaka Nithi County showed the lowest occurrence (26.36%) with a diversity index of (1.057). The diversity was influenced by the soil pH, texture and total organic content. This study reports for the first time a wide diversity of species from a semi-arid agroecosystem in Kenya with potential for utilization as low-cost, free-living nitrogen-fixing bioinoculant.
Topics: Azotobacter; Kenya; Nitrogen; RNA, Ribosomal, 16S; Soil; Soil Microbiology
PubMed: 35317624
DOI: 10.1098/rsbl.2021.0612 -
Microbiology (Reading, England) Apr 2018Azotobacter vinelandii has been studied for over 100 years since its discovery as an aerobic nitrogen-fixing organism. This species has proved useful for the study of... (Review)
Review
Azotobacter vinelandii has been studied for over 100 years since its discovery as an aerobic nitrogen-fixing organism. This species has proved useful for the study of many different biological systems, including enzyme kinetics and the genetic code. It has been especially useful in working out the structures and mechanisms of different nitrogenase enzymes, how they can function in oxic environments and the interactions of nitrogen fixation with other aspects of metabolism. Interest in studying A. vinelandii has waned in recent decades, but this bacterium still possesses great potential for new discoveries in many fields and commercial applications. The species is of interest for research because of its genetic pliability and natural competence. Its features of particular interest to industry are its ability to produce multiple valuable polymers - bioplastic and alginate in particular; its nitrogen-fixing prowess, which could reduce the need for synthetic fertilizer in agriculture and industrial fermentations, via coculture; its production of potentially useful enzymes and metabolic pathways; and even its biofuel production abilities. This review summarizes the history and potential for future research using this versatile microbe.
Topics: Azotobacter vinelandii; Biofuels; Biopolymers; Hydrogen; Metabolic Engineering; Metabolic Networks and Pathways; Nitrogen; Nitrogenase; Oxidoreductases; Oxygen
PubMed: 29533747
DOI: 10.1099/mic.0.000643 -
Microbiological Research Sep 2022In the present study Piriformospora indica (Pi) a phyto-promotional fungus and Azotobacter chroococcumWR5 (AzWR5) a rhizobacterium, were symbiotically evaluated for...
In the present study Piriformospora indica (Pi) a phyto-promotional fungus and Azotobacter chroococcumWR5 (AzWR5) a rhizobacterium, were symbiotically evaluated for their role in improving the nutritional quality of wheat (Triticum aestivum L.). Co-inoculation of Pi+AzWR5 modified root system architecture of host and along with increasing the proportion of finer roots by 88% and 92% in C306 and Hd2967 respectively. Furthermore, the synergistic impact of Pi+AzWR5 interplayed for enhanced accumulation of Zn and Fe in different plant parts including grains (3.12 and 1.33 fold respectively). Pi+AzWR5 increased the transfer factor of Zn (62%, 94%, 91% and 213%) and Fe (31%, 54%, 68% and 32%) in root, stem, leaves and grains, respectively, and translocation factor of Zn (20%, 18% and 63%) and Fe (18%, 29% and 29%) for root-stem, root-leaves and root-grains, respectively. In addition to these co-inoculation of endophytes led to several fold increase in expression of four ZIP transporter genes in roots and shoot. In addition to these symbiotic association of endophytes with host led to 3 fold increase in grain yield. We thereby conclude that co-inoculation of Pi+AzWR5 substantially improves mobilization of Zn and Fe from soil and increase its concentration in grains as well as improves crop yield.
Topics: Azotobacter; Basidiomycota; Biofortification; Endophytes; Iron; Plant Roots; Triticum; Zinc
PubMed: 35688099
DOI: 10.1016/j.micres.2022.127075 -
Bacteriological Reviews Dec 1954
Topics: Azotobacter; Body Fluids; Semen
PubMed: 13219046
DOI: 10.1128/br.18.4.195-214.1954 -
Journal of Applied Microbiology Oct 2017The effects of l-amino acids on growth and biofilm formation in Azotobacter chroococcum (Az) and Trichoderma viride (Tv) as single (Az, Tv) and staggered inoculated...
AIM
The effects of l-amino acids on growth and biofilm formation in Azotobacter chroococcum (Az) and Trichoderma viride (Tv) as single (Az, Tv) and staggered inoculated cultures (Az-Tv, Tv-Az) were investigated.
METHODS AND RESULTS
A preliminary study using a set of 20 l-amino acids, identified 6 amino acids (l-Glu, l-Gln, l-His, l-Ser, l-Thr and l-Trp) which significantly enhanced growth and biofilm formation. Supplementation of these amino acids at different concentrations revealed that 40 mmol l was most effective. l-Glu and l-Gln favoured planktonic growth in both single and in staggered inoculated cultures, while l-Trp and l-Thr, enhanced aggregation and biofilm formation. Addition of l-Glu or l-Gln increased carbohydrate content and planktonic population. Principal component analysis revealed the significant role of proteins in growth and biofilm formation, particularly with supplementation of l-Trp, l-Thr and l-Ser. Azotobacter was found to function better as biofilm under staggered inoculated culture with Trichoderma.
CONCLUSIONS
The results illustrate that amino acids play crucial roles in microbial biofilm formation, by influencing growth, aggregation and carbohydrates synthesized.
SIGNIFICANCE AND IMPACT OF THE STUDY
The differential and specific roles of amino acids on biofilm formation are of significance for agriculturally important micro-organisms that grow as biofilms, colonize and benefit the plants more effectively.
Topics: Amino Acids; Azotobacter; Biofilms; Carbohydrates; Cellular Microenvironment; Microbial Interactions; Plankton; Principal Component Analysis; Trichoderma
PubMed: 28731279
DOI: 10.1111/jam.13534 -
PeerJ 2023The raising trend of cultivation of ()-transgenic cotton is faced with a new challenge what effects on the growth and yield of cotton under elevated CO.
BACKGROUND
The raising trend of cultivation of ()-transgenic cotton is faced with a new challenge what effects on the growth and yield of cotton under elevated CO.
METHODS
Rhizobacteria is the significant biological regulator to increase environmental suitability and ameliorate soil-nitrogen utilization efficiency of crops, especially cotton. Pot-culture experiments investigated the effects on the yield and fiber quality components of cotton (transgenic Line SCRC 37) inoculated with (AC) under elevated CO.
RESULTS
The findings indicated that the inoculation of azotobacter significantly improved the yield and fiber quality components of cotton, the elevated CO significantly increased the soil density of and the partial yield indexes (as cottonweightper 20 bolls, lint yield per 20 bolls and boll number per plant), and non-significant decrease the fiber quality components of cotton except uniform.
DISCUSSION
Overall results obviously depicted that the inoculation of azotobacter and the elevated CO had positive effects on the yield and fiber quality components of cotton. Presumably, azotobacter inoculation can be used to stimulate plant soil-nitrogen uptake and promote plant growth for cotton under elevated CO in the future.
Topics: Bacillus thuringiensis; Carbon Dioxide; Azotobacter; Soil; Gossypium; Nitrogen
PubMed: 37576495
DOI: 10.7717/peerj.15811 -
Journal of Bacteriology Apr 1955
Topics: Azotobacter; Fluorescence
PubMed: 14367310
DOI: 10.1128/jb.69.4.481-482.1955 -
Applied and Environmental Microbiology Jan 2016In this study, we performed a detailed characterization of the siderophore metabolome, or "chelome," of the agriculturally important and widely studied model organism...
In this study, we performed a detailed characterization of the siderophore metabolome, or "chelome," of the agriculturally important and widely studied model organism Azotobacter vinelandii. Using a new high-resolution liquid chromatography-mass spectrometry (LC-MS) approach, we found over 35 metal-binding secondary metabolites, indicative of a vast chelome in A. vinelandii. These include vibrioferrin, a siderophore previously observed only in marine bacteria. Quantitative analyses of siderophore production during diazotrophic growth with different sources and availabilities of Fe showed that, under all tested conditions, vibrioferrin was present at the highest concentration of all siderophores and suggested new roles for vibrioferrin in the soil environment. Bioinformatic searches confirmed the capacity for vibrioferrin production in Azotobacter spp. and other bacteria spanning multiple phyla, habitats, and lifestyles. Moreover, our studies revealed a large number of previously unreported derivatives of all known A. vinelandii siderophores and rationalized their origins based on genomic analyses, with implications for siderophore diversity and evolution. Together, these insights provide clues as to why A. vinelandii harbors multiple siderophore biosynthesis gene clusters. Coupled with the growing evidence for alternative functions of siderophores, the vast chelome in A. vinelandii may be explained by multiple, disparate evolutionary pressures that act on siderophore production.
Topics: Azotobacter vinelandii; Bacterial Proteins; Biosynthetic Pathways; Chromatography, Liquid; Mass Spectrometry; Metabolome; Siderophores
PubMed: 26452553
DOI: 10.1128/AEM.03160-15 -
Scientific Reports Sep 2015Microbial communities in rhizosphere interact with each other and form a basis of a cumulative impact on plant growth. Rhizospheric microorganisms like Piriformospora...
Microbial communities in rhizosphere interact with each other and form a basis of a cumulative impact on plant growth. Rhizospheric microorganisms like Piriformospora indica and Azotobacter chroococcum are well known for their beneficial interaction with plants. These features make P. indica/A. chroococcum co-inoculation of crops most promising with respect to sustainable agriculture and to understanding the transitions in the evolution of rhizospheric microbiome. Here, we investigated interactions of P. indica with A. chroococcum in culture. Out of five Azotobacter strains tested, WR5 exhibited growth-promoting while strain M4 exerted growth-inhibitory effect on the fungus in axenic culture. Electron microscopy of co-culture indicated an intimate association of the bacterium with the fungus. 2-D gel electrophoresis followed by mass spectrometry of P. indica cellular proteins grown with or without WR5 and M4 showed differential expression of many metabolic proteins like enolase-I, ureaseD, the GTP binding protein YPT1 and the transmembrane protein RTM1. Fungal growth as influenced by bacterial crude metabolites was also monitored. Taken together, the results conform to a model where WR5 and M4 influence the overall growth and physiology of P. indica which may have a bearing on its symbiotic relationship with plants.
Topics: Azotobacter; Basidiomycota; Fungal Proteins; Microbial Interactions; Proteome; Proteomics; Secondary Metabolism
PubMed: 26350628
DOI: 10.1038/srep13911 -
Protein Science : a Publication of the... Oct 2017Azotobacter vinelandii flavodoxin II serves as a physiological reductant of nitrogenase, the enzyme system mediating biological nitrogen fixation. Wildtype A. vinelandii...
Azotobacter vinelandii flavodoxin II serves as a physiological reductant of nitrogenase, the enzyme system mediating biological nitrogen fixation. Wildtype A. vinelandii flavodoxin II was electrochemically and crystallographically characterized to better understand the molecular basis for this functional role. The redox properties were monitored on surfactant-modified basal plane graphite electrodes, with two distinct redox couples measured by cyclic voltammetry corresponding to reduction potentials of -483 ± 1 mV and -187 ± 9 mV (vs. NHE) in 50 mM potassium phosphate, 150 mM NaCl, pH 7.5. These redox potentials were assigned as the semiquinone/hydroquinone couple and the quinone/semiquinone couple, respectively. This study constitutes one of the first applications of surfactant-modified basal plane graphite electrodes to characterize the redox properties of a flavodoxin, thus providing a novel electrochemical method to study this class of protein. The X-ray crystal structure of the flavodoxin purified from A. vinelandii was solved at 1.17 Å resolution. With this structure, the native nitrogenase electron transfer proteins have all been structurally characterized. Docking studies indicate that a common binding site surrounding the Fe-protein [4Fe:4S] cluster mediates complex formation with the redox partners Mo-Fe protein, ferredoxin I, and flavodoxin II. This model supports a mechanistic hypothesis that electron transfer reactions between the Fe-protein and its redox partners are mutually exclusive.
Topics: Azotobacter vinelandii; Bacterial Proteins; Crystallography, X-Ray; Electrochemistry; Flavodoxin; Hydrogen-Ion Concentration; Iron; Models, Molecular; Nitrogenase; Protein Conformation
PubMed: 28710816
DOI: 10.1002/pro.3236