Root Associated Bacillus sp. Improves Growth, Yield and Zinc Translocation for Basmati Rice (Oryza sativa) Varieties

Plant associated rhizobacteria prevailing in different agro-ecosystems exhibit multiple traits which could be utilized in various aspect of sustainable agriculture. Two hundred thirty four isolates were obtained from the roots of basmati-385 and basmati super rice varieties growing in clay loam and saline soil at different locations of Punjab (Pakistan). Out of 234 isolates, 27 were able to solubilize zinc (Zn) from different Zn ores like zinc phosphate [Zn3 (PO4)2], zinc carbonate (ZnCO3) and zinc oxide (ZnO). The strain SH-10 with maximum Zn solubilization zone of 24 mm on Zn3 (PO4)2 ore and strain SH-17 with maximum Zn solubilization zone of 14-15 mm on ZnO and ZnCO3 ores were selected for further studies. These two strains solubilized phosphorous (P) and potassium (K) in vitro with a solubilization zone of 38-46 mm and 47-55 mm respectively. The strains also suppressed economically important rice pathogens Pyricularia oryzae and Fusarium moniliforme by 22-29 % and produced various biocontrol determinants in vitro. The strains enhanced Zn translocation towards grains and increased yield of basmati-385 and super basmati rice varieties by 22-49 % and 18-47 % respectively. The Zn solubilizing strains were identified as Bacillus sp and Bacillus cereus by 16S rRNA gene analysis

Wheat (Triticum aestivum L.) growth promotion by halo-tolerant PGPR-consortium

Salinity is among the major environmental factors that significantly affects the global crop production. Inoculation with plant growth promoting rhizobacteria (PGPR) increases crop productivity because PGPR convert the un-available forms of nutrients to plant-available form. With the aim to develop saline-soil specific biofertilizer, bacteria were isolated from rhizosphere of wheat grown in saline soil (EC 7.63 dS m.-1). Of total 21, eight bacteria showed halophilic (up to 65g L-1 NaCl), and four showed alkaliphilic (up to pH 9.5) trait; 12 isolates produced indole-3-acetic acid (411.5-9.33 mg L-1), 15 bacterial isolates solubilized inorganic tri-calcium phosphate (17.5-6.7 mg L-1), 14 isolates exhibited ACC-deaminase activity, and only one isolate solubilized the insoluble ZnO. A consortium of three potential PGPR strains (SAL-12, SAL-17, SAL-21; having multiple PGP traits) was tested for two years in laboratory and field experiments for wheat productivity with half dose of chemical fertilizer (NPK) under induced and natural salinity. The comparison of results with a non-halophilic wheat inoculum (BioPower containing Azospirillum and Pseudomonas spp.) indicated that both halo-tolerant and non-halo tolerant PGPR-consortia with reduced fertilizer dose have potential to increase the growth and yield of wheat in saline conditions. The relative increase in yield induced by halo-tolerant consortia was however, significantly better as compared to non-halo-tolerant PGPR inoculum that may be attributed to salt tolerance potential and stable PGP activities of PGPR indigenous to stressed environment. The study suggests using eco-friendly, cost-effective PGPR-biofertilization (inoculation) technology for wheat productivity in saline environments with reduced application of chemical fertilizers

Biopesticide activity of sugarcane associated rhizobacteria: Ochrobactrum intermedium strain NH-5 and Stenotrophomonas maltophilia strain NH-300 against red rot under field conditions

Colletotrichum falcatum is the major fungal pathogen causing sugarcane red rot. Four antagonistic bacterial strains exhibiting biocontrol activity against this pathogen in greenhouse conditions were characterized for production of different antifungal metabolites and biocontrol determinants to elucidate the mechanism of action involved in their antagonistic activity. The strains were also evaluated under field conditions to assess their biocontrol potential. All the strains produced hydrogen cyanide (HCN), and volatile and diffusible antibiotics. In addition, the Ochrobactrum intermedium strain NH-5 produced siderophores and the broad spectrum antibiotic 2, 4-diacetylphloroglucinol (2,4-DAPG); Pseudomonas sp. NH-203 produced siderophores, and Pseudomonas sp. NH-276 produced protease. Two strains, Ochrobactrum intermedium NH-5 and Stenotrophomonas maltophilia NH-300, exhibited good biocontrol activity, suppressing red rot by 44–52% on two sugarcane varieties, SPF-234 and Co-1148, in field experiments. The strains gave consistent results in three consecutive years and showed potential to be used as biopesticides

Differential response of kabuli and desi chickpea genotypes towards inoculation with PGPR in different soils

Pakistan is among top three chickpea producing countries but the crop is usually grown on marginal lands without irrigation and fertilizer application which significantly hampers its yield. Soil fertility and inoculation with beneficial rhizobacteria play a key role in nodulation and yield of legumes. Four kabuli and six desi chickpea genotypes were, therefore, evaluated for inoculation response with IAA-producing Ochrobactrum ciceri Ca-34T and nitrogen fixing Mesorhizobium ciceri TAL-1148 in single and co-inoculation in two soils. The soil type 1 was previously unplanted marginal soil having low organic matter, P and N contents than soil type 2 which was a fertile routinely legume-cultivated soil. The effect of soil fertility status was pronounced and fertile soil on average, produced 31% more nodules, 62% more biomass and 111 % grain yield than marginal soil. Inoculation either with O. ciceri alone or its co-inoculation with M. ciceri produced on average higher nodules (42%), biomass (31%), grains yield (64%) and harvest index (72%) in both chickpea genotypes over non-inoculated controls in both soils. Soil 1 showed maximum relative effectiveness of Ca-34T inoculation for kabuli genotypes while soil 2 showed for desi genotypes except B8/02. Desi genotype B8/02 in soil type 1 and Pb-2008 in soi

Biological control of sheath blight disease of rice by siderophore producing rhizobacterial strains and their role in efficient mobilisation of micronutrients from soil

Four siderophore producing rhizobacterial strains Bacillus cereus Z2-7, Enterobacter sp. B41 strain SPR7, Aeromonas hydrophila BPS10 and Enterobacter sp. BPS12 isolated from rice grown in saline soils were examined for induction of chitinases, glucanases and peroxideses (POX) in rice plants against sheath blight pathogen R. solani and mobilization of micronutrients from rice rhizosphere to straw and grain of rice plant. Atomic absorption studies indicated that rice plants preinoculated with Bacillus cereus Z2-7 have an increased uptake of zinc, copper and iron as compared to uninoculated control plants. High content of copper and iron were present in straw while high quantity of zinc was found in grains. Straw of rice plants inoculated with Enterobacter sp. B41 strain SPR7 contained highest Manganese content as compared to other treatments and uninoculated control plants. Gene expression analysis revealed enhanced levels of chitinase, peroxidase and glucanase expression in rice plants preinoclated with bacterial strains Z2-7 and SPR7 after 7 and 52 days of challenge inoculation with R. solani. Improved uptake of micronutrients and induction of defence enzymes in these plants resulted in an increase in yield of these plants as compared to rest of the treatments

Molecular and biochemical characterization of surfactin producing Bacillus species antagonistic to Colletotrichum falcatum Went causing sugarcane red rot

Bacillus species suppress phytopathogens by producing lipopeptide antibiotics, hydrolytic enzymes, siderophores and other secondary metabolites. Three bacterial strains Bacillus subtilis NH-100 (EU627167), B. subtilis NH-160 (EU627169) and Bacillus sp. NH-217 (EU627170) with proven ability to suppress red rot disease on sugarcane plants were further characterized to elucidate the multiple modes of action involved in their biocontrol activity. Plate assays pointed out the production of protease and antibiotics. Lipopeptide antibiotic surfactin was detected in the culture extract of B. subtilis NH-160 and Bacillus sp. NH-217 through LC-MS (Liquid chromatography - mass spectrometry). These results were further supported by identifying the presence of sfp and srfAC genes of surfactin biosynthetic operon using specific polymerase chain reaction (PCR) primers. Two strains B. subtilis NH-160 and Bacillus sp. NH-217 were further analyzed for their survival in compost which successfully retained consistency in their population 4.0 - 5.0 log CFUg -1 after 14th day. Bacteria capable of suppressing pathogens and maintaining their population by competing with other microbes can be successfully utilized as biopesticide for sustainable organic farming. © 2010 Academic Journals

Bacillus spp., a bio-control agent enhances the activity of antioxidant defense enzymes in rice against Pyricularia oryzae.

Plant growth promoting rhizobacteria (PGPR) are found to control the plant diseases by adopting various mechanisms. Induced systemic resistance (ISR) is an important defensive strategy manifested by plants against numerous pathogens especially infecting at aerial parts. Rhizobacteria elicit ISR by inducing different pathways in plants through production of various metabolites. In the present study, potential of Bacillus spp. KFP-5, KFP-7, KFP-17 was assessed to induce antioxidant enzymes against Pyricularia oryzae infection in rice. The antagonistic Bacillus spp. significantly induced antioxidant defense enzymes i-e superoxide dismutase (1.7-1.9-fold), peroxidase (3.5-4.1-fold), polyphenol oxidase (3.0-3.8-fold), phenylalanine ammonia-lyase (3.9-4.4-fold), in rice leaves and roots under hydroponic and soil conditions respectively. Furthermore, the antagonistic Bacillus spp significantly colonized the rice plants (2.0E+00-9.1E+08) and secreted multiple biocontrol determinants like protease (1.1-5.5 U/mg of soil or U/mL of hydroponic solution), glucanase, (1.0-1.3 U/mg of soil or U/mL of hydroponic solution), siderophores (6.5-42.8 μg/mL or mg) in the rhizosphere of different rice varieties. The results showed that treatment with Bacillus spp. enhanced the antioxidant defense activities in infected rice, thus alleviating P. oryzae induced oxidative damage and suppressing blast disease incidence

Plant growth-promoting bacteria as biofertilizer

Seventeen rhizobacteria isolated from different ecological regions, i.e. Brazil, Indonesia, Mongolia and Pakistan were studied to develop inoculants for wheat, maize and rice. Almost all the bacterial isolates were Gram-negative, fast-growing motile rods and utilized a wide range of carbon sources. These isolates produced indole-3-acetic acid at concentrations ranging from 0.8–42.1 µg/mL, irrespective of the region. Fifteen isolates fixed N at rates ranging from 20.3–556.8 nmole C2H2 reduced/h/vial. Isolate 8N-4 from Mongolia produced the highest amount of indole-3-acetic acid (42.1 µg/mL), produced siderophores (0.3 mg/mL) and was the only isolate that solubilized phosphate (188.7 µg P/mL). Inoculation of the wheat variety Orkhon with 8N-4 isolate resulted in the maximum increase in plant biomass, root length, and total N and P contents in plants. Random amplified polymorphic deoxyribonucleic acid (RAPD) analysis, conducted with 60 decamer primers, revealed a high level of polymorphism among the bacterial isolates from different geographic regions and a low level of polymorphism among isolates from the same region. The complete 16S rRNA gene sequence analysis demonstrated that 8N-4 is a Bacillus pumilus strain (Accession number AY548949). It was concluded that Bacillus pumilus 8N-4 can be used as a bio-inoculant for biofertilizer production to increase the crop yield of wheat variety Orkhon in Mongolia

A Review on Nanoparticles as Boon for Biogas Producers—Nano Fuels and Biosensing Monitoring

Nanotechnology has an increasingly large impact on a broad scope of biotechnological, pharmacological and pure technological applications. Its current use in bioenergy production from biomass is very restricted. The present study is based on the utilization of nanoparticles as an additive to feed bacteria that break down natural substances. The novel notion of dosing ions using modified nanoparticles can be used to progress up biogas production in oxygen free digestion processes. While minute nanoparticles are unstable, they can be designed to provide ions in a controlled approach, so that the maximum enhancement of biogas production that has been reported can be obtained. Nanoparticles are dissolved in a programmed way in an anaerobic atmosphere and are supplied in a sustainable manner to microbiotic organisms responsible for the degradation of organic material, which is a role that fits them well. Therefore, biogas fabrication can be increased up to 200%, thereby increasing the degradation of organic waste