Amount Of Indole-3-acetic Acid Research Articles

In vitro antagonistic potential, plant growth-promoting activity and indole-3-acetic acid producing trait of bacterial isolates from spent mushroom substrate of Agaricus bisporus

Spent mushroom substrate (SMS) is widely used as fertilizer and to control plant diseases. The microorganisms surviving in SMS play a crucial role in plant growth promotion and biocontrol properties of SMS. In this study, an effort was made to isolate and characterize the bacterial species present in the SMS of Agaricus bisporus and to study their antagonistic potential, plant growth-promoting ability and indole-3-acetic acid (IAA) producing trait. Six different bacterial isolates exhibiting morphological variabilities were obtained from the SMS by serial dilution technique. On the basis of 16S rRNA gene sequences, these isolates were identified as Staphylococcus epidermidis (Sh1 and Sh3), S. aureus (Sh2), Bacillus albus (Sh4), Delftia lacustris (Sh6) and Comamonas aquatica (Sh7). These bacterial strains were assayed for their antagonism against Pythium aphanidermatum, a phytopathogenic oomycete. The results of in vitro dual culture assay revealed that all the 6 bacterial isolates showed low levels of suppression of P. aphanidermatum and recorded less than 5 mm inhibition zone. Among the bacterial isolates, S. epidermidis Sh3 recorded the maximum inhibition zone of 4.2 mm. Plant growth promotion test using roll paper towel method revealed that C. aquatica Sh7, B. albus Sh4, D. lacustris Sh6 and S. epidermidis Sh3 caused a significant increase in seedling vigour of cucumber compared to control. The seeds treated with the bacterial isolate C. aquatica Sh7 showed the maximum seedling vigor. Assessment of in vitro production of IAA by the bacterial isolates revealed that the bacterial isolates highly varied (ranging from 0.28 to 9.25 mg L-1) in their potential for production of IAA. The maximum amount of IAA was produced by C. aquatica Sh7 (9.25 mg L-1), while the minimum was produced by S. epidermidis Sh1 (0.28 mg L-1).

Evaluation of Multifarious Plant Growth Promoting Trials of Yeast Isolated from the Soil of Assam Tea (Camellia sinensis var. assamica) Plantations in Northern Thailand.

Some soil microorganisms, especially bacteria and mycorrhizal fungi, play a role in the promotion of plant growth. However, plant growth promotion involving yeasts in soil has not yet been extensively investigated. This study aimed to isolate and identify yeast strains obtained from soils of the Assam tea plant (Camellia sinensis var. assamica) in northern Thailand and to investigate their plant growth promoting capabilities. A total of 42 yeast strains were obtained and identified by analysis of the D1/D2 domain of the large subunit ribosomal RNA gene. We identified 35 strains of six species belonging to the phylum Ascomycota, namely Aureobasidium melanogenum, Kazachstania aquatica, Saturnispora diversa, Saturnispora sekii, Schwanniomyces pseudopolymorphus and Wickerhamomyces anomalus, and six species were determined to belong to the phylum Basidiomycota, namely Apiotrichum scarabaeorum, Curvibasidium pallidicorallinum, Papiliotrema laurentii, Rhodosporidiobolus ruineniae, Trichosporon asahii and Trichosporon coremiiforme. Seven strains were representative of potential new species and belonged to the genera Galactomyces and Wickerhamomyces. A total of 28 strains were found to produce indole-3-acetic acid (IAA) in a range of 2.12 to 37.32 mg/L, with the highest amount of IAA produced by R. ruineniae SDBR-CMU-S1-03. All yeast strains were positive in terms of ammonia production, and only eight strains were positive for siderophore production. Two yeast species, P. laurentii and W. anomalus, were able to solubilize the insoluble form of calcium and zinc. The ability to produce amylase, endogulcanase, lipase, pectinase, protease and xylanase was dependent upon the yeast species and strain involved.

Isolation, characterization, and optimization of indole acetic acid–producing Providencia species (7MM11) and their effect on tomato (Lycopersicon esculentum) seedlings

Abstract Indole-3-acetic acid (IAA) is the most prevalent plant hormone of the auxin family that occurs naturally in the environment and regulates the plant growth and development. The bacteria were isolated from the tomato rhizosphere soils and screened for IAA production. Among the all isolates, the isolate designated as 7MM11 showed maximum amount of IAA (89.22 μg/mL) production in short incubation period (24 h) by HPLC. The isolate was identified as Providencia sp. by its morphological characteristics and 16S rRNA sequence study. Further, optimal conditions such as l -tryptophan concentration, incubation time, agitation, pH, carbon sources, and nitrogen sources, were identified for IAA production. The optimization results suggested that the IAA production increased with medium supplemented with sucrose (0.1%), urea (0.1%), and tryptophan (0.1%) with pH 8.0 at 30 ± 2 °C on a shaker at 150 rpm after 24 h of incubation. The production of IAA by Providencia sp. was further confirmed and characterized with help of thin-layer chromatography and high-performance liquid chromatography. In an in vivo experiment, the tomato seedlings treated with Providencia sp. showed improved germination, seedling vigor index, and enhanced growth promotion compared to un-inoculated control. Thus, the results of this study suggest that Providencia sp. strain 7MM11 is a potent isolate for the maximum production of IAA in short period, which may help in achieving the plant growth promotion.

Stainless steel sheets as the substrate of disposable electrochemical sensors for analysis of heavy metals or biomolecules

In this paper, low-cost stainless steel sheets with excellent electric conductivity were utilized as the robust substrate for fabrication of disposable working electrodes. The stainless steel electrodes were modified with carbon cement and then coupled in paper-based analytical devices for analysis of heavy metals (cadmium and lead) in toys or indole-3-acetic acid (IAA) in plants, respectively. For stripping analysis of cadmium and lead, the dilution ratio of the carbon cement, the pH value of the buffer solution, the pre-deposition potential and time, and the bismuth concentration were optimized with the detection limits reaching 1 μg•L−1. After optimization of the dilution ratio of carbon cement, the similar devices could also be used for analysis of IAA at the concentration of less than 0.5 μM. This strategy could be successfully applied for differentiation of migratable lead in toys or in situ amounts of IAA in root tips of Arabidopsis thaliana in real time, respectively. Our results implied that the electric conductivity of the substrate could possibly be critical for the improvement of the analytical performance of the modified electrodes. This study suggested that stainless steel could become a suitable and cost-effective substrate for fabrication of disposable carbon-based electrodes used in electrochemical detection.

Overproduction of Some Plant Growth Promoters by Rhizospheric Microorganisms on Natural Medium

Considering the nutritional values of Mentha viridis. L and Aloe veraplants, these plants can be utilized for the production of alternative cultivation media. The cost of artificial culture media is very high, and some components may be unavailable. Use of the plant-based culture media would drastically reduce the expense of the synthetic media. Fifteen bacterial isolates were isolated from Aloe vera rhizosphere, nine bacterial and nine actinomycetes isolates were isolated from Mentha viridis rhizosphere both cultivated in Sirs EL- Layan, El-Menoufia governorate, Egypt. In-vitroscreening was done for the production of indole acetic acid (IAA) and phosphorus solubilization. Results revealed that bacterial isolate No. MB4 produced a high amount of IAA(36.51 μg/ml) on the Mentha-based culture medium, No. A6 showed maximum IAA production (16.25μg/ml) on the Aloe vera-based culture medium and isolate No. MA6 was efficient in phosphorus solubilization (867.85μg/ml) that was isolated from the Mentha viridis. L rhizosphere.16s rRNA analysis of these isolates revealed they are (Pseudomonas monteilii strain CIP 104883, Streptomyces rochei strain DW3 and Kosakonia radicincitans strain DSM 16656 respectively.

Plant growth promoting potential of Brevibacterium sediminis A6 isolated from the tea rhizosphere of Assam, India

Abstract The Tea rhizosphere microbial community harbor diverse plant growth promoting (PGP) rhizobacteria and are relatively less explored. In our study, we isolated 23 distinct bacterial morphotypes from the tea garden of Assam, India. The isolates were screened for their plant growth promotion (PGP) and antifungal traits against three pathogenic fungi, namely Rhizoctonia solani, Corticium rolfsii, and Fomes lamaensis. Out of 23 isolates, 7 isolates showed potential in antifungal activities, amongst which, isolate A6 was found to have promising PGP and antifungal traits. Isolate A6 also exhibited biosurfactant production abilities in the presence of 2% dextrose as a carbon source. Biochemical and molecular characterization revealed its identity as Brevibacterium sediminis. Further quantification assay showed the amount of indole acetic acid (IAA) production (72.51 ± 2.18 μg/mL) and phosphate solubilization (60.644 ± 3.098 μg/mL) by the isolate A6. The PGP activity of the isolate was validated by in vitro trials on rice seedlings. A6 treated seedlings showed a significantly higher root length (p = 0.0350), shoot length (p

Isolation and identification of indole acetic acid producing bacteria from the coasts of Ben Tre and Tra Vinh Provinces

Beneficial plant-growth-promoting bacteria (PGPB) have been reasonably applied to rescue crucial issue for agriculture by salinity soil. Observed most of PGPB was found in endophyte, rhizosphere and soil. Indole acetic acid (IAA)-producing bacteria could naturally stimulate and facilitate plant growth. The knowledge of IAA production and content of bacteria resident in the marine environment has been typically insufficient and limited to date. In recent years, unwarrantable intrusions of sea water have been enlarged in the Mekong River Delta of Vietnam, threatening productive rice fields, local fruits, and cash crops. Therefore, finding PGPB in the coastal regions in the Mekong River Delta as a creative resource for sustainable agriculture is necessary and is a prompt challenge. In this study, IAA-producing bacteria from coastal regions of Ben Tre and Tra Vinh Provinces were isolated and adequately identified. Out of 202 bacterial isolates, 10 isolates showed the possible ability to produce IAA from L-tryptophan. These 10 isolates were objectively evaluated the capacity to produce IAA under 5% (w/v) NaCl in King B and marine broths. The results revealed that IAA production decreased in 5% NaCl, even though bacterial growth increased. These 10 IAA-producing bacteria were classified at the species level, Marinobacter hydrocarbonoclasticus, M. pelagius, M. daepoensis, and Mameliella phaeodactyli by 16S rRNA gene analysis. The most IAA producer in King’s B broth, the isolate C7, was investigated in more detail. The isolate C7 produced the maximum IAA amount (192.2 ± 1.14 µg/ml) under the presence of 20 g/l yeast extract, 2 g/l of L-tryptophan and 1% NaCl. The isolate C7 was able to grow at 1–17% (w/v) NaCl (optimum, 4%), but not in the absence of NaCl, indicating it is a moderate halophilic bacteria. This study highlighted the considerable ability to produce IAA of marine bacteria, which could be thoughtfully considered to use naturally as biofertilizers to promote plant growth in saline intrusion lands.

Isolation and identification of indole acetic acid producing bacteria from the coasts of Ben Tre and Tra Vinh Provinces

Beneficial plant-growth-promoting bacteria (PGPB) have been reasonably applied to rescue crucial issue for agriculture by salinity soil. Observed most of PGPB was found in endophyte, rhizosphere and soil. Indole acetic acid (IAA)-producing bacteria could naturally stimulate and facilitate plant growth. The knowledge of IAA production and content of bacteria resident in the marine environment has been typically insufficient and limited to date. In recent years, unwarrantable intrusions of sea water have been enlarged in the Mekong River Delta of Vietnam, threatening productive rice fields, local fruits, and cash crops. Therefore, finding PGPB in the coastal regions in the Mekong River Delta as a creative resource for sustainable agriculture is necessary and is a prompt challenge. In this study, IAA-producing bacteria from coastal regions of Ben Tre and Tra Vinh Provinces were isolated and adequately identified. Out of 202 bacterial isolates, 10 isolates showed the possible ability to produce IAA from L-tryptophan. These 10 isolates were objectively evaluated the capacity to produce IAA under 5% (w/v) NaCl in King B and marine broths. The results revealed that IAA production decreased in 5% NaCl, even though bacterial growth increased. These 10 IAA-producing bacteria were classified at the species level, Marinobacter hydrocarbonoclasticus, M. pelagius, M. daepoensis, and Mameliella phaeodactyli by 16S rRNA gene analysis. The most IAA producer in King’s B broth, the isolate C7, was investigated in more detail. The isolate C7 produced the maximum IAA amount (192.2 ± 1.14 µg/ml) under the presence of 20 g/l yeast extract, 2 g/l of L-tryptophan and 1% NaCl. The isolate C7 was able to grow at 1–17% (w/v) NaCl (optimum, 4%), but not in the absence of NaCl, indicating it is a moderate halophilic bacteria. This study highlighted the considerable ability to produce IAA of marine bacteria, which could be thoughtfully considered to use naturally as biofertilizers to promote plant growth in saline intrusion lands.

Composting of Vegetable Waste Using Microbial Consortium and Biocontrol Efficacy of Streptomyces Sp. Al-Dhabi 30 Isolated from the Saudi Arabian Environment for Sustainable Agriculture

Thirty-seven root-associated Actinomycetes were isolated from the tomato plant for plant growth promoting activity. Among these, ten were selected for phosphate solubilisation, the production of siderophores, and indole acetic acid. Out of ten, eight Actinomycetes solubilised phosphate, whereas, Streptomyces sp. Al-Dhabi 30 showed better activity (43.1 mg/dL). Actinomycetes produced siderophore and the concentration ranged between 1.6 and 42.1 μg/mL. Streptomyces sp. Al-Dhabi 30 showed the ability to produce a maximum amount of indole acetic acid (IAA) (43 μg/mL), chitinase (43.1 U/mL), cellulase (67 U/mL), and protease (121 U/mL) than other strains. Further, vegetable waste was used as the bulk material for composting using Streptomyces sp. Al-Dhabi 30 along with microbial consortium. Total nitrogen content was 3.8% in Streptomyces sp. Al-Dhabi 30 inoculated compost, whereas 2.7% organic nitrogen was detected in the control. In the compost vegetable waste, the C:N ratio was 10.07, whereas it was 17.51 in the control. The vegetable waste composted with Streptomyces sp. Al-Dhabi 30, Lactobacillus plantarum ATCC 33222, and Candidautilis ATCC 9950 showed antagonistic activity and the supplemented compost enhanced shoot, root height, and total weightin tomato plants. These findings clearly suggest the use of Streptomyces sp. Al-Dhabi 30 as a potential biocontrol agent.

Isolation and selection of highly effective phosphate solubilizing bacterial strains to promote wheat growth in Egyptian calcareous soils

BackgroundForty phosphate solubilizing bacterial (PSB) isolates were isolated from the root zone of wheat plants cultivated in the Delta and the Northwestern coast regions of Egypt. All isolates proofed their ability to dissolve tricalcium phosphate on the National Botanical Research Institute's phosphate growth medium (NBRIP) by producing clear zone and increasing the available phosphorus that ranged between 40 and 707 mg l−1. They were designated as Egyptian native phosphate solubilizing bacteria (ENPSB).ResultsAll strains proofed their ability to dissolve tricalcium phosphate on (NBRIP) medium by producing clear zone and increasing the available phosphorus that ranged between 40 and 707 mg l−1. The ENPSB 1, 2, and 3 strains were highly efficient as they gave 707, 653, and 693 mg l−1 soluble phosphorus respectively. Intriguingly, the two highly efficient strains for phosphate solubilization were isolated from the Northwestern coast alkaline soils. Moreover, 75% of strains were also produced profitable amounts of indole acetic acid (IAA) ranged from 0.79 to 50.5 mg l−1. Amazingly, the most efficient strain ENPSB 1 in solubilizing phosphorus (707 mg l−1soluble P) was the best one for producing IAA (50.5 mg l−1). The three efficient strains were identified using the sequencing of 16S rRNA. Sequence analysis of 16S rRNA for selected strains confirmed that the strains ENPSB 1, 2, and 3 were genetically closed to Enterobacter aerogenes; Pantoea sp. and Enteriobacter sp. respectively.ConclusionThe inoculation by mix cultures of strains (ENPSB 1, 2, and 3) contributed to raising the dry weight and P content of wheat plants by 76% and 12% over the full fertilized plants. Inoculation of soil PSB can be used to solve the deficiency of phosphorus and promote plant growth effectively in calcareous soils.

Isolation, Screening and Response of Maize to Plant Growth Promoting Rhizobacteria Inoculants

Abstract The use of plant growth promoting rhizobacteria (PGPR) as biofertilizer is a relatively safer, environment friendly and cost effective. This work was designed to assess plant growth promoting abilities of rhizobacteria and evaluate their effect on germination and growth of maize. The bacteria were isolated and screened for plant growth promoting abilities using Pikovskaya agar, Aleksandrov agar and Jensen media. Twelve isolates that showed multiple attributes were further screened for indole acetic acid (IAA) and gibberellic acid (GA) production; best five isolates were selected for further studies. The results of IAA and GA production showed a considerable amount of IAA and GA produced by the isolates which ranged between 9–94 and 21–97 mg l–1, respectively. The selected isolates identified as Bacillusmojavensis, Pseudomonas aeruginosa, Alcaligenes faecalis, Pseudomonas syringae and Bacillus cereus showed a significant difference(P≤0.05) in the amount of potassium(K) and phosphorus(P) solubilized at different source of K (KCl and mica powder) and P (Ca2PO4 and rock phosphate). The isolates also recorded significant level of nitrogen fixing ability with Alcaligenes faecalis strain P156 fixing the highest amount of nitrogen (11.4 mg N fixed per l) and least by Bacillus mojavensis strain NBSL51 (6.3 mg N fixed per l).The results of plant inoculation test showed that Bacillus cereus strain 20UPMNR significantly enhanced the root and shoot dry weight. All the selected isolates enhanced shoot and root length except Bacillus mojavensis which produced less effect on root length when compared to the control. These results have provided vital information for the development of a bio fertilizer for maize.

ISOLATION AND SCREENING OF SOIL YEASTS FOR PLANT GROWTH PROMOTING TRAITS

Soil microorganisms are the key player of biochemical and biological processes of the soil and govern the soil health and sustain agricultural production. Yeast is one of the potential plant growth promoting organisms when compared to bacteria and filamentous fungi. In this study, potential plant growth promoting yeast isolates were isolated from garden land soil. All the yeast isolates were screened based on morphological and antibiotic resistance. Several plant growth promoting abilities of the yeast isolates were investigated. The yeast isolates were tested for mineral solubilization of Zinc, phosphate, and potassium (K). Among the isolates, SY7 showed maximum Zn solubilization potential. For P solubilization and K releasing, SY10 yeast isolate showed maximum potential when compared to others. The results revealed that SY2 yeast isolate, produced the maximum amount of indole acetic acid (IAA), Gibberellic acid (GA3). The isolate, SY6 exhibited better siderophore activity and positive for HCN production. Hence, it is concluded that soil yeast may be considered as potential plant growth promoting agents. .

Aspergillus flavus Promoted the Growth of Soybean and Sunflower Seedlings at Elevated Temperature.

The current climate changes in the form of global warming are one of the leading threats to agricultural crops (including soybean and sunflower). To enable the crops to cope with the heat stress, innovative steps are needed to be taken as soon as possible. Fungal endophytes are known to secrete secondary metabolites that promote the growth of host plants under stress conditions. Therefore, we have isolated endophytic fungus from Euphorbia indica (a wild desert plant) and tested it for plant growth promoting activities. The culture filtrate of the fungal strains exhibited the presence of secondary metabolites. Higher amounts of indole acetic acid (IAA), salicylic acid (SA), flavonoids, and phenolics have been found in the culture filtrate. The 18S rDNA sequence homology and phylogenetic analysis revealed that the isolate is Aspergillus flavus. Soybean and sunflower seedlings were inoculated with the identified A. flavus. The A. flavus-associated seedlings along with the control (without A. flavus) were monitored for thermal stress resistance in a growth chamber, operated at 25°C and 40°C. Control seedlings exposed to high temperature stress had higher levels of abscisic acid (ABA), proline, and lower levels of phenols, flavonoids, catalase, and ascorbic acid oxidase. Similarly, a higher reduction in chlorophyll, root-shoot length, and dry weight has been noticed in the control seedlings. The results suggested the usefulness of A. flavus in host plant growth promotion under heat stress conditions.

Indole-3-acetic-acid and ACC deaminase producing Leclercia adecarboxylata MO1 improves Solanum lycopersicum L. growth and salinity stress tolerance by endogenous secondary metabolites regulation

BackgroundThe utilization of plant growth-promoting microbes is an environment friendly strategy to counteract stressful condition and encourage plants tolerance. In this regards, the current study was designed to isolate ACC deaminase and indole-3-acetic acid (IAA) producing halotolerant bacteria to promote tomato (Solanum lycopersicum L.) growth and tolerance against salinity stress.ResultsThe selected bacterial isolate MO1 was identified as Leclercia adecarboxylata and IAA quantification results revealed that MO1 produced significant amount of IAA (9.815 ± 0.6293 μg mL− 1). The MO1 showed the presence of ACC (1-Aminocyclopropane-1-Carboxylate) deaminase responsible acdS gene and tolerance against salinity stress. A plant microbe interaction experiment using tomato (Solanum lycopersicum L.) with glycine betaine (GB) as a positive control was carried out to investigate the positive role MO1 in improving plant growth and stress tolerance. The results indicated that MO1 inoculation and GB application significantly increased growth attributes under normal as well as saline condition (120 mM NaCl). The MO1 inoculation and GB treatment approach conferred good protection against salinity stress by significantly improving glucose by 17.57 and 18.76%, sucrose by 34.2 and 12.49%, fructose by 19.9 and 10.9%, citric acid by 47.48 and 34.57%, malic acid by 52.19 and 28.38%, serine by 43.78 and 69.42%, glycine by 14.48 and 22.76%, methionine by 100 and 124.99%, threonine by 70 and 63.08%, and proline by 36.92 and 48.38%, respectively, while under normal conditions MO1 inoculation and GB treatment also enhanced glucose by 19.83 and 13.19%, sucrose by 23.43 and 15.75%, fructose by 15.79 and 8.18%, citric acid by 43.26 and 33.14%, malic acid by 36.18 and 14.48%, serine by 46.5 and 48.55%, glycine by 19.85 and 29.77%, methionine by 22.22 and 38.89%, threonine by 21.95 and 17.07%, and proline by 29.61 and 34.68% compared to levels in non-treated plants, respectively. In addition, the endogenous abscisic acid (ABA) level was noticeably lower in MO1-inoculated (30.28 and 30.04%) and GB-treated plants (45 and 35.35%) compared to their corresponding control plants under normal condition as well as salinity stress, respectively.ConclusionThe current findings suggest that the IAA- and ACC-deaminase-producing abilities MO1 can improve plants tolerance to salinity stress.

Effect of Inoculation with Cyanobacterial Strains and Nitrogen Fertilization on Yield and Component of Rice Plant

The nitrogen fixed by blue-green algae could supply rice plants with their needs of nitrogen. Cyanobacteria can fix atmospheric nitrogen in submerged rice fields. A field experiment was carried out at Rice Research and Training Center, Sakha Research Station, Agricultural Research Center ( ARC ) Kafer EL-Sheikh, Egypt during the summer season 2016 to investigate the effect of biofertilizers as inoculants (Anabaena oryzae D and Nostoc muscorum K) . The both cyanobacterial strains were selected according to the amount of indole acetic acid and nitrogenase activities. The results indicated that highly significant increase in plant height, panicle length, number of tillers/plant, number of panicles/plant, biomass and grain yield t/ha. On the other hand , there were no significant for 1000 grain weight and harvest index. The cyanobacteria have been saved the inorganic nitrogen application by 20-25% compare with recommended nitrogen application.

Tuyển chọn vi khuẩn có khả năng cố định đạm, hòa tan lân, tổng hợp IAA nội sinh trong cây cà phê vối (Coffea canephora Pierre ex A. froehner) trồng tại tỉnh Đắk Lắk

Coffea canephora is an industrial plant for the people of Tay Nguyen. The application of bio-fertilizer has been conducted in order to replace inorganic fertilizers because bio-fertilizer could support high yield and keep the healthy environment. In this research, one hundred bacterial strains were isolated from roots, leaves and berries of Coffea canephora, grown in Ea H’leo and Krong Nang districts, Dak Lak province. The morphological characteristics of almost colonies were round shape, raised or convex elevation, entire margin, pure white or milky white or yellow. Almost bacterial cells had rod shape, motile, Gram negative and all of them made pellicles in LGIP, NFb and BAz semi solid media after seventy-two hours of incubation. The results showed that strain L.R150-3 had the highest ability of N2-fixing with 0.289 mg/L of NH4+ concentration, while strain B.R157-2 had the highest ability of solubilizing insoluble phosphate with 4.30 mg P2O5/mL and strain L.R150-1 gave the highest amount of indole acetic acid at 19.206 μg/mL. Three strains L.R150-3, B.R157-2 and L.R150-1 were determined respectively as Kosakonia sp. L.R150-3, Burkholderia sp. strain Eb-6 (KJ865578.1) B.R157-2 and Enterobacter sp. L.L150-1.

Plant growth promoting potential of Aspergillus sp. NPF7, isolated from wheat rhizosphere in South Gujarat, India

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.

Optimization of IAA production by endophytic Bacillus spp. from Vigna radiata for their potential use as plant growth promoters

Endophytic bacteria isolated from nodules ofVigna radiatawere screened for indole acetic acid (IAA) production. Three isolates MBN3, MJHN1 and MJHN10, molecularly identified asBacillus aryabhattai(MF693121.1),B. megaterium(MF693120.1) andB. cereus(MF693119.1) were producing significantly high amount of IAA. Production parameters viz. L-tryptophan concentration, incubation time, carbon and nitrogen sources were optimized. The study revealed the presence of trp-dependent pathway for IAA production in the isolates. All of them gave maximum production with yeast extract as nitrogen source but variation in preference for carbon sources was observed. The invitro application of bacterial isolates on plant roots resulted in increase in root length as well as number of lateral roots. These results confirm the occurrence ofBacillusas predominant non-rhizobial endophytic genera in summer season crop and its potential as plant root growth promoter.

Genetic diversity of plant growth promoting rhizobacteria and their effects on the growth of maize plants under greenhouse conditions

Engineering of plant rhizosphere with beneficial plant growth promoting (PGP) bacteria offers a great promise for sustainable crop productivity. In this context, 49 rhizospheric/endophytic bacterial isolates were purified using N-free medium, screened in vitro for PGP characteristics and evaluated for their beneficial effects on the early growth of maize (Zea mays L.). The biodiversity of isolated bacteria was analyzed by amplified ribosomal DNA restriction analysis (ARDRA) using four restriction enzymes. Out of the 49 isolates, 7 produced high levels (32.1–82.8 μg mL−1) of indole-3-acetic acid (IAA); 11 had potential phosphate solubilizing abilities (101–163 μg mL−1), while significant acetylene reduction activities (100–1800 nmole C2H4 mg−1 protein h−1) were observed in 12 isolates. Five ribogroups (A-E) were identified using ARDRA. The 16S rRNA-sequence analysis of bacterial representatives from different ribogroups revealed that, 89% of isolates belonged to phylum Proteobacteria, while 11% of them were assigned into phylum Bacteroidetes. Phylum Proteobacteria included Achromobacter, Agrobacterium, Bordetella, Cupriavidus, Ochrobactrum, Pseudoxanthomonas and Stenotrophomonas genera. While, phylum Bacteroidetes was represented by Chryseobacterium and Flavobacterium genera. Under greenhouse conditions, all the selected isolates significantly increased shoot and root fresh and dry biomass of maize plants, compared to the non-inoculated control. Inoculation with Chryseobacterium sp. NGB-29 and Flavobacterium sp. NGB-31 showed the highest beneficial effects on plant growth parameters that were tentatively associated with the high efficiency of these isolates to fix nitrogen and produce high amounts of IAA. The study indicates the potential use of these isolates for production of maize biofertilizers under field conditions.

Assessment of toxic impact of metals on proline, antioxidant enzymes, and biological characteristics of Pseudomonas aeruginosa inoculated Cicer arietinum grown in chromium and nickel-stressed sandy clay loam soils.

Considering the heavy metal risk to soil microbiota and agro-ecosystems, the study was designed to determine metal toxicity to bacteria and to find metal tolerant bacteria carrying multifarious plant growth promoting activities and to assess their impact on chickpea cultivated in stressed soils. Metal tolerant strain SFP1 recognized as Pseudomonas aeruginosa employing 16S rRNA gene sequence determination showed maximum tolerance to Cr (400μg/ml) and Ni (800μg/ml) and produced variable amounts of indole acetic acid, HCN, NH3, and ACC deaminase and could solubilize insoluble phosphates even under Cr (VI) and Ni stress. Metal tolerant P. aeruginosa reduced toxicity of Cr (VI) and Ni and concomitantly enhanced the performance of chickpea grown under stressed and conventional soils. At 144mgCrkg-1, the measured parameters of a bacterial strain was significantly enhanced, but it was lower compared to those recorded at 660mgNikg-1. The strain SFP1 demonstrated maximum increase in seed yield (81%) and grain protein (16%) at 660mgNikg-1 over uninoculated and untreated control. Stressed plants had more proline, antioxidant enzymes, and metal concentrations in plant tissues. P. aeruginosa, however, remarkably declined the level of stress markers (proline and APX, SOD, CAT, and GR), as well as with Cr (VI) and Ni uptake by chickpea. Conclusively, P. aeruginosa strain SFP1 due to its dual metal tolerant ability, capacity to secrete plant growth promoting regulators even under metal stress and potential to mitigate metal toxicity, could be developed as microbial inoculant for enhancing chickpea production in Cr and Ni contaminated soils.