Environmental Adaptations of an Extremely Plant Beneficial Bacillus subtilis Dcl1 Identified Through the Genomic and Metabolomic Analysis.

Bacterial endophytes ubiquitously colonize the internal tissues of plants and promote the plant growth through diverse mechanisms. The current study describes the mechanistic basis of plant-specific adaptations present in an extremely beneficial endophytic bacterium. Here, the endophytic Bacillus subtilis Dcl1 isolated from the dried rhizome of Curcuma longa was found to have the drought tolerance, IAA and ACC deaminase production and phosphate solubilization properties. The whole genome sequencing and annotation further showed the genome of B. subtilis Dcl1 to have the size of 4,321,654 bp. This also showed the presence of genes for IAA, H2S, acetoin, butanediol, flagella and siderophore production along with phosphate solubilization and biofilm formation for the B. subtilis Dcl1. In addition, the genes responsible for the synthesis of surfactin, iturin, fengycin, bacillibactin, bacillaene, bacilysin, chitinase, chitosanase, protease and glycoside hydrolase could also be annotated from the genome of B. subtilis Dcl1. Identification of genes for the glycine betaine, glutamate and trehalose further indicated the drought stress tolerance features of B. subtilis Dcl1. The presence of the genetic basis to produce the catalase, superoxide dismutase, peroxidases, gamma-glutamyltranspeptidase, glutathione and glycolate oxidase also indicated the plant oxidative stress protective effect of B. subtilis Dcl1. Identification of these properties and the demonstration of its plant probiotic effect in Vigna unguiculata confirmed the applicability of B. subtilis Dcl1 as a biofertilizer, biocontrol and bioremediator agent to enhance the agricultural productivity.

Drought-tolerant and plant growth-promoting endophytic Staphylococcus sp. having synergistic effect with silicate supplementation.

Endophytic bacteria have been reported to have symbiotic, mutualistic, commensalistic or trophobiotic relationships with various plant parts. As part of its adaptation, many endophytic organisms are known to exhibit properties with multiple beneficial effects to the plant system. Even though many bacterial genera have been identified to have endophytic association, isolation of those which were previously demonstrated well for human association is quite interesting. In the study, endophytic bacteria Ceb1 isolated from the rhizome of Curcuma longa was identified by 16S rDNA sequencing as Staphylococcus sp. Further, Ceb1 was observed to have the ability to tolerate drought stress. While screening for the plant growth-promoting traits, Ceb1 was found to be positive for IAA production both under drought-stressed and normal conditions as confirmed by HPLC. The Ceb1 priming with Vigna unguiculata was observed to enhance the growth parameters of the plant. Analysis of Ceb1-treated plants by ICP-MS further showed modulation of both macro- and micronutrients. Upon drought stress induction in Vigna unguiculata, Ceb1 was found to provide synergistic plant growth-promoting effect to the plant along with the supplemented silicate sources. Under the changing agroclimatic conditions, exploring the plant stress-alleviating effects of endophytes is highly significant.

Starch-PVA composite films with zinc-oxide nanoparticles and phytochemicals as intelligent pH sensing wraps for food packaging application.

The increasing acceptance of ready to eat food generates demand on development of active and intelligent food packaging material. Even though many polymers have been used for the packaging, they have limitations for broad applications. Among the various polymers, Poly Vinyl Alcohol is a promising film forming polymer with highly flexible, emulsifying and adhesive properties. A variety of nano-fabrication techniques have already been reported to improve the mechanical and antimicrobial properties of PVA to exploit its wider applications. In the present study, starch-PVA based composite films incorporated with zinc oxide nanoparticles and phytochemicals were prepared by solvent casting technique. The films were characterized by XRD, FT-IR, UV-Vis spectrometry and SEM. The developed nanocomposite films were demonstrated to have enhanced water barrier, mechanical and antimicrobial properties. The unique features of the nanocomposite with its pH indication property demonstrated in the study indicate its potential usage in food packaging applications.

Plant Growth Enhancement, Disease Resistance, and Elemental Modulatory Effects of Plant Probiotic Endophytic Bacillus sp. Fcl1.

Endophytic bacteria have already been studied for their beneficial support to plants to manage both biotic and abiotic stress through an array of well-established mechanisms. They have either direct or indirect impact on mobilizing diverse nutrients and elements from soil to plants. However, detailed insight into the fine-tuning of plant elemental composition by associated microorganism is very limited. In this study, endophytic Bacillus Fcl1 characterized from the rhizome of Curcuma longa was found to have broad range of plant growth-promoting and biocontrol mechanisms. The organism was found to have indole acetic acid and 1-aminocyclopropane-1-carboxylate deaminase production properties along with nitrogen fixation. The Bacillus Fcl1 could also inhibit diverse phytopathogens as confirmed by dual culture and well diffusion. By LC-MS/MS analysis, chemical basis of its antifungal activity has been proved to be due to the production of iturin A and a blend of surfactin compounds. Moreover, the organism was found to induce both plant growth and disease resistance in vivo in model plant system. Because of these experimentally demonstrated multiple plant probiotic features, Bacillus Fcl1 was selected as a candidate organism to study its role in modulation of plant elemental composition. ICP-MS analysis of Bacillus Fcl1-treated plants provided insight into relation of bacterial interaction with elemental composition of plants.

Accumulation of intracellular polyhydroxybutyrate in Alcaligenes sp. d(2) under phenol stress.

Alcaligenes sp. d(2) isolated from soil was earlier reported as a potent phenol-degrading organism. In the Fourier transform/infrared spectroscopic analysis of the biodegraded sample, the aromatic stretching was missing and the spectrum gave evidence for the presence of polyhydroxybutyric acid along with its depolymerized products. In the gas chromatogram of the biodegraded sample, the peak of phenol at 14.997 min was absent and there were many peaks after 20 min. The organism could carry out 100% degradation of phenol in 32 h and could progressively result in early accumulation of polyhydroxybutyrate (PHB) intracellularly from 8 h onwards. The various conditions optimized for the maximum accumulation of intracellular PHB were pH 7.0, incubation time 24 h, phenol concentration 15 mg/100 ml, and ammonium sulfate concentration 25 mg/100 ml.

Treatment of paper factory effluent using a phenol degrading Alcaligenes sp. under free and immobilized conditions.

Treatment of the paper factory effluent was done with free and immobilized cells of a phenol degrading Alcaligenes sp. d(2). The free cells could bring a maximum of 99% reduction in phenol and 40% reduction in chemical oxygen demand (COD) after 32 and 20 h of treatment, respectively. In the case of immobilized cells, a maximum of 99% phenol reduction and 70% COD reduction was attained after 20 h of treatment under batch process. In the continuous mode of operation using packed bed reactor, the strain was able to give 99% phenol removal and 92% COD reduction in 8h of residence time The optimum flow rate was 2.5 ml/h and the half life period was 76 h. Even after the complete removal of phenol, the strain could further enhance reduction in chemical oxygen demand, which clearly indicated that in the paper factory effluent, this strain could also oxidize organic matter other than phenol.