Nitrogen fixing bacteria facilitate microbial biodegradation of a bio-based and biodegradable plastic in soils under ambient and future climatic conditions

We discovered a biological mechanism supporting microbial degradation of bio-based poly (butylene succinate-co-adipate) (PBSA) plastic in soils under ambient and future climates. Here, we show that nitrogen-fixing bacteria facilitate the...

Nitrogen Fixing Bacteria and Their Application for Heavy Metal Removal: A Mini Review

Nitrogen is a critical component of biological systems and typically serves as a constraint on production in both aquatic and terrestrial environments, although its shortage has been compensated for through the process of biological nitrogen fixation. Nitrogen fixation is a critical microbial activity that utilises nitrogenase enzymes to convert dinitrogen (N2) gas to ammonia (NH3). It is carried out by a diverse spectrum of bacteria known as nitrogen fixing bacteria. These include free-living bacteria such as Azotobacter, Bacillus, Beijerickia, and Clostridium, associative bacteria such as Azospirillum, Enterobacter, and Pseudomonas, and bacteria that form symbiotic associations with legumes such as Rhizobium and actinorrhizal plants such as Frankia. These bacteria contribute significantly to plant growth by producing phytohormones (such as auxins, cytokinins, gibberelins, and indole acetic acid), reducing the incidence of plant diseases through the production of siderophores and cell wall degrading enzymes, and increasing phosphorus nutrition via phosphate solubilization. Additionally, they remove heavy metal ions from solutions through a process called biosorption, which is a feasible, natural, environmentally benign, and economically viable technique of remediating heavy metal-contaminated environments.

Distribution of Heterotrophic and Nitrogen fixing Rhizobacteria in Irrigation Sites of Lake Alau Borno State Northeastern Nigeria

This study was conducted to know the population of rhizobacteria in both irrigation and non-irrigation sites of the dam. The dense population of these organism indirectly promote plant growth and development. Five sites (A, B, C, D and E) were used to collect soil samples randomly and transported to the laboratory for analysis. Total heterotrophic bacterial count was done using nutrient agar (NA) and nitrogen fixing bacteria was counted using Ashbey’s media (AM). The result shows that highest number of total heterotrophic bacteria in site C (46.0×106) cfu/g in irrigation site whereas higher count in non-irrigation site was (13.0×106) site D, the nitrogen fixing bacterial count in irrigation site was higher at site E with (12.0×106) and for the non-irrigation site was higher at site D with (14.0×106) The total heterotrophic bacteria isolated in the soil sample are the species of Bacillus alvei, Bacillus alvei, Bacillus cereus, Bacillus cereus, Pseudomonas putida, Klebsiella aeruginosa and Enterobacter aeruginosa. Likewise, the Nitrogen fixing bacteria isolated are the species of Rhizobium leguminosarum, Klebsiella pneumonia, Bacillus lentus, Azotobacter nigricans, Azotobacter tropicalis, Azotobacter spp, and Azotobacter tropicalis. The long history of agricultural activities in the lake area has directly influenced the diversity of microbial population in the area.

ISOLATION, MOLECULAR CHARACTERIZATION OF DIAZOTROPIC BACTERIA FROM VIRGIN SOIL FROM ARAKU VALLEY AND ASSESSMENT OF OF AMMONIA ACCUMULATION AT SALINE CONDITIONS

Nitrogen-fixing bacteria are widely distributed in nature where they reduce atmospheric nitrogen in soil or in association with plant. They have been found in a wide variety of terrestrial and aquatic habitats in both temperate and tropical regions of the word. Nitrogen-fixing bacteria are found in symbiotic associations with plants free living in soil. The objective of the present research was to isolate free living Nitrogen fixing bacteria from virgin soil samples in araku valley and assessment of their ammonia accumulation at saline conditions. 10 soil samples were collected in different place from virgin areas. For isolation of the free living nitrogen fixing bacteria, Nitrogen free media like Jensens Medium and Azotobacter Agar were used. Serially diluted soil samples were spread on the agar media and incubated for 48 hours. Eleven morphologically different bacteria were separated on made pure colonies on nutrient agar media. All bacteria were under go biochemical characterization which reveals that all these bacteria related to Azospirillum, Azotobacter and Clostridium. High ammonia liberating isolate MGN-10 was molecular characterizes as Azotobacter chroococcum and this soil application increase the plant growth in terms of growth parameters.

Diversification of plasmids in a genus of pathogenic and nitrogen-fixing bacteria

Members of the agrobacteria–rhizobia complex (ARC) have multiple and diverse plasmids. The extent to which these plasmids are shared and the consequences of their interactions are not well understood. We extracted over 4000 plasmid sequences from 1251 genome sequences and constructed a network to reveal interactions that have shaped the evolutionary histories of oncogenic virulence plasmids. One newly discovered type of oncogenic plasmid is a mosaic with three incomplete, but complementary and partially redundant virulence loci. Some types of oncogenic plasmids recombined with accessory plasmids or acquired large regions not known to be associated with pathogenicity. We also identified two classes of partial virulence plasmids. One class is potentially capable of transforming plants, but not inciting disease symptoms. Another class is inferred to be incomplete and non-functional but can be found as coresidents of the same strain and together are predicted to confer pathogenicity. The modularity and capacity for some plasmids to be transmitted broadly allow them to diversify, convergently evolve adaptive plasmids and shape the evolution of genomes across much of the ARC. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

Effects of organic and inorganic fertilization with bio-inoculants on the sustainable management of plant-parasitic nematodes infesting okra (Abelmoschus esculentus)

Root-knot nematodes are believed to be amongst the biological constraints causing severe damage and a great reduction in the productivity of okra. The purpose of this study was to apply organic matter and non-symbiotic nitrogen-fixing bacteria to minimize the addition of chemical fertilizers that constantly pollute the environment. Experimental studies were conducted in the field for two summers to determine the effect of inoculations of non-symbiotic nitrogen-fixing bacteria, such as Azotobacter chroococcum and Azospirillum brasilense singly and in combinations, with different recommended doses of inorganic nitrogen as well as organic matter such as neem seed cake on the growth, yield, and organic parameters of the okra crop towards the management of plant-parasitic nematodes. The results show a significant reduction in nematode multiplication through soil application of nitrogen-fixing bacteria and neem seed cake along with different recommended doses of nitrogen inoculated plants. Azotobacter was found to be less effective than Azospirillum in agronomic parameters and nematode control. The most pronounced increases were observed in the yield and growth parameters such as plant height, fresh as well as dry weights, fruit weights/plant, number of total fruits/plant and primary branches, chlorophyll content, and ascorbic acid content when A. chroococcum and A. brasilense were added concomitantly in various combinations. Agronomic parameters such as NPK content in the plant as well as in residual soil increased considerably in almost all the combinations irrespective of these biofertilizers and neem seed cake. In conclusion, the combined application of a 100% recommended dose of nitrogen fertilizer along with Azospirillum and neem seed cake is recommended for better growth and yield of okra with better control of nematodal population.

Vegetative growth response of upland rice to Actinomycetes, Azospirillum and Azotobacter

The research aims is to determine the suitability of nitrogen fixing bacteria, namely Actinomycetes, Azospirillum and Azotobacter with upland rice seeds to the speed of radicle formation and growth of upland rice plants. Upland rice plant growth measurement parameters include; speed of formation of radicle length, upland rice plant height, number of upland rice tillers, dry weight of the top of upland rice plants and roots of upland rice plants, wet weight of upland rice plants and roots of upland rice plants, and total N of upland rice plants and upland roots Testing the application of N2 fixing bacteria on upland rice plants on a laboratory scale was carried out to determine the suitability of microbes with upland rice plant seeds in vitro. The pot test was carried out to determine the suitability of the N2 fixing bacteria with the vegetative growth of upland rice plants in vivo. Data were analyzed using ANOVA with Duncan’s advanced test. The results showed that upland rice plants inoculated with Actinomycetes, Azospirillum and Azotobacter showed significantly different growth from upland rice plants without nitrogen fixing bacteria treatment, namely the radicle formation speed and radicle length, plant height, number of tillers, wet weight, dry weight, and total N (%) plants. It can be concluded that the inoculation of nitrogen-fixing bacteria on upland rice plants has a significant effect on plant vegetative growth parameters and plant nitrogen content.