Multifarious functional traits of free-living rhizospheric fungi, with special reference to Aspergillus spp. isolated from North Indian soil, and their inoculation effect on plant growth (original) (raw)
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Many plant growth promoting fungi (PGPF) that perform well under laboratory conditions, fail to do so under natural conditions. Only those PGPF that are acclimatized to the local agro-climatic conditions, can efficiently grow as compared to those that are brought from different agroclimatic conditions. PGPF isolated from local rhizosphere soil and used as locally adapted bio-inoculants are expected to give better performance. Production of phytohormones is an inherent property in all groups of PGPF. Here we report gibberellic acid (GA), indole acetic acid (IAA), siderophore producing and phosphate (P) solubilizing Aspergillus sp. NPF7 isolated from wheat rhizosphere as PGPF for wheat and chickpea. In total 12 fungal isolates were obtained from the different rhizosphere of four local crops in the vicinity of Surat city, Gujarat, India. Isolate, NPF7 produced copious amount of IAA (96 μgmL −1), GA (184.11 μgmL −1) and siderophore (87% SU) and efficiently solubilized phosphate (790 mgL −1). It was identified as Aspergillus sp. on the basis of homology of its 18S rDNA sequencing. Inoculation of plants with Aspergillus sp. promoted growth of wheat and chickpea significantly, enhanced germination index and root and shoot length over the control (uninoculated seeds). Aspergillus sp. NPF7 producing multiple plant growth promoting metabolites can be useful bioinoculant for wheat and chickpea.
Soil bacteria are able to synthesize a wide range of metabolites with fungicidal activity. Nine bacterial isolates were obtained from the botanical garden of University of Calabar. Preliminary examination of isolates was carried out using morphological characteristics and biochemical analysis. These isolates were designated with codes SB1, SB2, SB3, SB4, SB5, SB6, SB7, and SB8. Bacterial isolates were evaluated for their potentials of antagonism against Aspergillus niger isolated from spoiled vegetables like tomatoes by using agar diffusion technique. Percentage inhibition of mycelial growth by these isolates recorded values as 27%, 0%, 66%, 40%, 97%, 0% and 23% respectively. Isolates were analyzed through several biochemical tests and were identified as Bacillus sp., Enterobacter spp., Pseudomonas spp., Proteus spp., Escherichia coli, Streptococcus spp. and Staphylococcus spp. respectively. These result indicated that bacterial species exhibited varying degree of antagonism against the fungus Aspergillus niger. Escherichia coli showed maximum inhibitory potential against tested fungus with reduction of up to 97% in their mycelial fungal growth, followed by Pseudomonas spp. and Bacillus spp. with 66.7% reduction. From the results obtained, it is found that the bacterial species isolated from the soil samples are effective as antifungal agents against phyto-pathogenic fungi. Escherichia coli, Pseudomonas spp., Bacillus spp. had more antagonistic effect on vegetative growth of tested fungi (Aspergillus niger). These bacterial species showed higher levels of inhibitory effect on fungal spore germination. The presented data exhibit the antifungal activity of bacterial species and indicate the possibility of using these bacterial species as a biological agent to control the phyto pathogenic fungi.
2019
Plant growth-promoting fungi (PGPF) are a class of non-pathogenic soil-borne filamentous fungi that have beneficial effects on plants. It has been reported that PGPF increase the plant growth directly or indirectly by fixing nitrogen, producing phytohormones, inducing systemic resistance etc. The association of PGPF with plant roots has also been shown to modulate growth, morphology, nitrogen assimilation, resource allocation and mineral uptake of the host plant and also improves host reproductive fitness with subsequent increase in biomass and grain yield of crop plants. So, by considering the beneficial effects of PGPF and the growing demands of biofertilizers for sustainable agriculture, our focus was to isolate and characterize the PGPF from the rhizospheric soil of the plant Aloe barbadensis Mill. growing in Burdwan district, West Bengal, India. After isolation, the isolated PGPF were studied for their plant growth promoting traits like, Phosphate solubilising property, IAA pro...
Plant Science Today
In the present study, indole-3-acetic acid (IAA) producing plant growth promoting fungus was isolated from rice field of Purba Bardhaman district, West Bengal, India. Among the isolated 6 strains, AP2 (Aspergillus fumigatus) was selected as best-performing plant growth promoting fungal strain as it was an efficient indole-3-acetic acid producer as well as exhibits different plant growth promoting ability viz, phosphate solubilization, siderophore production, ammonia and hydrogen cyanide production etc. Media and different growth conditions (pH, temperature, concentration of sodium chloride) were optimized for augmentation of the indole-3-acetic acid production. The genus of the selected isolate AP2 was identified as Aspergillus fumigatus both by 18S rDNA sequence-based homology and MALDI-TOF analyses of ribosomal protein. Plant growth promoting ability of Aspergillus fumigatus has been confirmed by measuring different morphological and biochemical growth parameters in Trigonella foe...
Antagonistic Potential of Soil Bacteria against Plant Pathogenic Fungi: Aspergillus niger
Aims: This study was carried out with the aim of assessing the antagonistic potentials of soil bacteria against the plant pathogenic fungi Aspergillus niger. Study Design: The complete Randomized Design was the experimental design for this study. Place and duration of study: This study took place in University of Calabar, Cross River State Nigeria within the pace of one month. Methodology: Standard microbiological methods were used to identify bacteria and obtain pure culture of fungi Results: Bacterial isolates were evaluated for their potential of antagonism against Aspergillus niger isolated from spoilt tomatoes. The percentage inhibition of mycelia growth by these isolates recorded values as 27%, 0%, 66%, 40%, 97%, 0% and 23% respectively. The isolates were analyzed and identified as Bacillus spp, Enterobacter spp., Pseudomonas spp., Proteus spp., Escherichia coli, Streptococcus spp. and Staphylococcus spp respectively. Conclusion: In the present work high levels of in vitro control of A. niger have been verified by E. coli isolates. However, in future investigations molecular studies should be carried out confirming that the isolates obtained from E. coli are not pathogenic to humans.
Journal of Bangladesh Academy of Sciences, 2021
Plant growth promoting rhizobacteria (PGPR) residing in soil rhizosphere provide enormous beneficial effects to a plant host producing diverse secondary metabolites and enzymes useful for plant growth and protection. Siderophores, antibiotics, volatile compounds and hydrolytic enzymes are the major molecules secreted by the PGPRs, which have substantial antifungal properties and can provide plant protection. These compounds are responsible for the lysis and hyperparasitism of antagonists against deleterious fungal pathogens. Siderophore-producing PGPRs function by depriving the pathogen of iron nutrition. Antibiotics have been reported to be involved in the suppression of different fungal pathogens by inducing fungistasis, inhibition of spore germination, lysis of fungal mycelia. The PGPRs also secrete a wide range of low molecular weight volatile organic compounds (VOCs) that inhibit mycelial growth, sporulation, germination of phytophathogenic fungi, etc. Hydrolytic enzymes, mostl...
Microbial Biosystems, 2020
Microbes are ubiquitous in nature, and plant-microbe interactions are a key strategy for colonizing diverse habitats. Fungi are producing a wide range of secondary metabolites and bioactive compounds, which are probable alternative sources of drugs and/or antibiotics. Fungi are associated with the crops and plays an important role in plant growth promotion and enhanced soil fertility using different PGP mechanism such as solubilization of phosphorus, zinc, potassium; production of plant growth regulator (auxins, cytokinin, gibberellins, ethylene and abscisic acid); hydrolytic enzymes (xylanases, laccase, pectinases, cellulases); and siderophores. Besides eliciting plant defence reaction against pathogens; PGP fungi also help in plant growth promotion and alleviation of different abiotic stresses under harsh environments. The PGP fungi have reported from different genera of phyla Chytridiomycota, Zygomycota, Glomeromycota, Ascomycota, and Basidiomycota. Fungi also have significant potential applications in various industries like medical, and food. In the medical applications, fungi and fungal products are used to control disease in human and animals. In the fermentation industries fungi used to make alcoholic beverages, cheeses, bread, kefir, yogurt and various other food preparations and the agricultural sectors used to make plant healthy and protects to pathogens. The present review, deals with the biodiversity of beneficial fungi from different habitats and their biotechnological applications in plant growth promotion and soil health
Screening for bioactivity and optimization of process parameters affecting growth of soil Fungi
Natural products generally show novel mechanisms of action and exhibit higher therapeutic activities in comparison to synthetic or combinatorial compounds. Fungi are one of the major antibiotic producing and most diverse groups of organisms, so the research for novel antibiotics from fungi is promising. The aim of this study was to isolate fungi from subsurface soils of Mahakaushal region and evaluate their antibacterial potential against human pathogenic bacteria. The serial dilution method was employed for isolating fungi from soil samples and the isolates were identified by slide culture technique along with consulting various literatures. All the fungi were screened for antibacterial activity against the test bacteria through agar well diffusion assay. The isolate showing exceptional antibacterial activity was further selected for growth pattern studies. Effect of variable culture media, temperature, hydrogen ion concentration and agitation levels was determined for optimizing the culture conditions for maximum vegetative growth of fungus. A total of 50 fungi were isolated from the soil samples and Paecilomyces variotii was found to be highly effective against all the test bacteria exhibiting clear zones of inhibition. The isolate was grown in five different media including natural and synthetic and Potato Dextrose Broth was found to be the suitable medium. Similarly, the highest dry weight of mycelium was obtained when the fungus was cultivated at 28ºC with agitation at 150 rotations per minute in rotary shaker. When the fungus was grown in medium adjusted to different concentrations of hydrogen ion, it was deduced that the optimum pH for growth of fungus was found to be 6.5.
BioResources
Inducing hydrolytic enzymes production and antibiosis is an attractive process for industrial applications. The approach can be used to repress pathogenic microorganisms. Using a dual culture of Aspergillus fumigatus and Aspergillus flavus, the activities of cellulase, polygalacturonase, chitinase, β-1,3-glucanases, protease, xylanase, and β-glucosidase were 1.78, 3.87, 2.98, 2.79, 6.91, 2.89 U, and 1.43 U∙mg-1 of protein. Meanwhile, the activities were 0.87, 2.78, 0.58, 1.69, 4.45, 2.06, and 0.89 U.mg-1 of protein for A. flavus alone and 0.98, 2.98, 0.87, 1.89, 4.98, 2.58, and 0.91 U.mg-1 of protein for A. fumigatus alone. The cellulase, polygalacturonase, and chitinase activities were studied at different temperatures; 40 °C and 50 °C, which were better temperatures than 20 °C in terms of enzymes activity for A. fumigatus and the dual culture compared to A. flavus. The highest antimicromial activity was observed using the dual fungal culture, where the inhibition zones were 3.13, ...
Soil Biology and Biochemistry, 2003
Seven most efficient phytase and phosphatases producing fungi were isolated from the soils of arid and semi-arid regions of India and tested for their efficiency on hydrolysis of two important organic P compounds: phytin and glycerophosphate. The native soil organic P may be exploited after using these organisms as seed inoculants, to help attain higher P nutrition of plants. The identified organisms belong to the three genera: Aspergillus, Emmericella and Penicillium. Penicillium rubrum released the most acid into the medium during growth. Aspergillus niger isolates were found to accumulate biomass the fastest. A significant negative correlation (r ¼ 20:593; n ¼ 21; p , 0.01) was observed between the development of fungal mat and pH of the media. The extracellular (E) phosphatases released by different fungi were less than their intracellular (I) counterpart, but the trend was reversed in case of phytase production. The E:I ratio of different fungi ranged from 0.39 to 0.86 for acid phosphatase, 0.29 to 0.41 for alkaline phosphatases and 9.4 to 19.9 for phytase. The efficiency of hydrolysis of different organic P compounds of different fungi varied from 2.12-4.85 mg min 21 g 21 for glycerophosphate to 0.92-2.10 mg min 21 g 21 for phytin. The trend of efficiency was as follows: Aspergillus sp.. Emmericella sp.. Penicillium sp. The results indicated that the identified fungi have enough potential to exploit native organic phosphorus to benefit plant nutrition.