Paenibacillus Lentimorbus Research Articles

Mechanistic insights to Paenibacillus lentimorbus mediated biocontrol of Alternaria solani in Solanum lycopersicum L. through carbohydrate reallocation and sweet immunity suppression

Researchers envisaged that PGPR (plant growth promoting rhizobacteria) has vast possibilities as a bioinoculant that will lead to revolution. However, it's still very far from becoming commercially successful. Here, the information regarding the root colonization of PGPR in host plants and plant response towards PGPR is inadequate. It can provide valuable information for developing successful biofertilizers and biocontrol agents. PGPR (Paenibacillus lentimorbus NRRL B-30488 or CHM12) has been previously reported as a successful commercial biofertilizer and biocontrol agent. However, the exact mechanism of plant growth promotion and biocontrol is poorly studied. So, CHM12 was appraised for biotic stress amelioration of pathogen Alternaria solani in Tomato (Solanum lycopersicum L.) var. S-22 plants. PGPR CHM12 was assessed for various plant growth parameters such as proline, sugar content, etc. in pathogen A. solani (AS) challenged plants and compared with the CHM12 treated plants in a greenhouse study. Then, the metabolomics tool (GC-MS) was used to identify metabolites and their respective genes playing pivotal roles in colonization tactics availed by PGPR. Further, gene expression analysis was done to affirm the involvement of various genes related to metabolites providing biotic stress tolerance in Tomato plants. The current research discerned that PGPR CHM12 revealed significant differences in different plant growth parameters studied. There were 33 distinct metabolites identified, which stipulated the involvement of carbohydrate metabolism mainly in combating biotic stress in this study. Thus, our study reconfirmed very few reported previous results through gene expression analysis, suggesting the downregulation of carbohydrate metabolism genes in PGPR-treated plants. This downregulation of carbohydrate genes might be the critical factor for suppressing the plant's immune response to gaining entry inside the host plant. This also helps in retaining and reallocating carbohydrates in plant cells to reduce pathogen proliferation.

Paenibacillus lentimorbus alleviates nutrient deficiency-induced stress in Zea mays by modulating root system architecture, auxin signaling, and metabolic pathways.

Paenibacillus lentimorbus reprograms auxin signaling and metabolic pathways for modulating root system architecture to mitigate nutrient deficiency in maize crops. The arable land across the world is having deficiency and disproportionate nutrients, limiting crop productivity. In this study, the potential of plant growth-promoting rhizobacteria (PGPR) viz., Pseudomonas putida, Paenibacillus lentimorbus, and their consortium was explored for growth promotion in maize (Zea mays) under nutrient-deficient conditions. PGPR inoculation improved the overall health of plants under nutrient-deficient conditions. The PGPR inoculation significantly improved the root system architecture and also induced changes in root cortical aerenchyma. Based on plant growth and physiological parameters inoculation with P. lentimorbus performed better as compared to P. putida, consortium, and uninoculated control. Furthermore, expression of auxin signaling (rum1, rul1, lrp1, rtcs, rtcl) and root hair development (rth)-related genes modulated the root development process to improve nutrient acquisition and tolerance to nutrient-deficient conditions in P. lentimorbus inoculated maize plants. Further, GC-MS analysis indicated the involvement of metabolites including carbohydrates and organic acids due to the interaction between maize roots and P. lentimorbus under nutrient-deficient conditions. These findings affirm that P. lentimorbus enhance overall plant growth by modulating the root system of maize to provide better tolerance to nutrient-deficient condition.

Synergistic eco-physiological response of biochar and Paenibacillus lentimorbus application on chickpea growth and soil under drought stress

This study aims to develop an eco-compatible soil amendment employing maize-stalk-derived biochar in conjunction with plant-beneficial rhizobacteria, Paenibacillus lentimorbus (B-30488) to improve soil properties and chickpea growth under drought conditions. Our results unveiled significant alterations in soil physicochemical properties, enzyme activities, and culturable microbial diversity on the application of B-30488+Biochar treatment. Scanning electron microscopy confirmed the porous structure of biochar, facilitating efficient colonization by B-30488. Under drought conditions, the synergistic application of biochar and B-30488 substantially enhanced chickpea growth as indicated by improved biochemical and physiological status, root architecture, and anatomy. Additionally, phytohormone [Indole acetic acid (IAA), cytokinin (CK), jasmonic acid (JA), and salicylic acid (SA)] and gene expression [glutathione S-transferase (GST), ascorbate peroxidase (APX), catalase (CAT) and ACC oxidase (ACO)] analyses affirmed their regulatory role in maintaining cellular homeostasis during drought stress. These findings underscore the multifaceted role of the synergistic application of B-30488 and Biochar, offering a sustainable strategy for agriculture and stress resilience.

Purification and structural characterization of Chojalactone C, a promising anticancer compound from a marine bacterium, Paenibacillus lentimorbus SAGM 3

Purification and structural characterization of Chojalactone C, a promising anticancer compound from a marine bacterium, Paenibacillus lentimorbus SAGM 3

ISOLATION AND CHARACTERIZATION OF CELLULOSE-DEGRADING BACTERIA FROM DECOMPOSING PLANT MATTER

Objective: The green plant waste consists of a high amount of lignocellulosic materials offering an intense environment for the growth of cellulolytic bacteria, which have ability to degrade plant biomass as a carbon source. This cellulase produced can be used to break down plant waste into valuable products such as monomeric sugars, biofuels, compost etc. Therefore, the aim of present study was to isolate and identify potent cellulose-degrading bacteria from decomposing plant matter and assessment of their cellulolytic activity. Methods: The cellulolytic bacteria were isolated by serial dilution technique on CMC agar media and six isolates were selected based on their cellulose hydrolysing ability. Based on the biochemical tests such as Oxidase test, Voges-Proskauer test, Methyl red test, Catalase test and sequence analysis of 16s rRNA genes. Results: The isolates were identified as Paenibacillus alvei, Paenibacillus lentimorbus, Bacillus subtilis, Bacillus nakamurai with percentage identity of 93.77%, 92.80%, 97.71% and 91.94%, respectively, as obtained from NCBI BLAST. Among these Paenibacillus alvei showed the highest cellulase activity. Conclusion: The findings of this study could pave the way for the use of cellulose as an inexpensive energy source for bacteria that are capable of producing valuable products.

Isolation and Characterization of Anticancer Compound Producing Marine Paenibacillus lentimorbus SAGM 3 Collected from a Sea Anemone, Heteractis species

Sea anemone-associated bacteria were considered promising candidates for the synthesis of many novel bioactive compounds. Thus culturable symbiotic bacteria that exist in the sea anemones met much attention when compared to other benthic marine dwellers. In this study, an attempt was made to explore the anticancer potentials of symbiotic bacteria isolated from a sea anemone, Heteractis species. Nine symbiotic bacteria were isolated, pure cultured and screened for their anticancer potential using two breast cancer cell lines. Among the strains, SAGM 3 showed appreciable growth inhibition activity of 43.1% and 47.1% against the studied cell lines, viz. MCF7 and MDA-MB-231 and this strain was selected for further studies. Based on the 16S rRNA molecular profiling, the SAGM 3 isolate was noted as Paenibacillus lentimorbus and the sequence of SAGM 3 was deposited in GeneBank with the accession number MW737456.1. During the growth kinetics profiling, maximum bacterial growth rate and anticancer activities were recorded from 60 to 96 hrs of incubation. The present investigation provides baseline data understanding the pharmaceutical significance of a symbiotic marine bacterium procured from the sea anemone, Heteractis species.

BACTERIA FOR COTTON PLANT PROTECTION: DISEASE CONTROL, CROP YIELD AND FIBER QUALITY1

ABSTRACT Ramulosis (Colletotrichum gossypii var. cephalosporioides) is an important fungal disease of cotton in Brazil, exclusively controlled by fungicide application. Therefore, sustainable management of ramulosis is essential. This work aimed to evaluate the potential of three bacterial strains, Bacillus amyloliquefaciens (UFLA285), Bacillus velezensis (UFLA401), and Paenibacillus lentimorbus (MEN2), for the biocontrol of ramulosis in cotton and their effects on yield and fiber quality. Seed treatment (ST), foliar spray, and soil drenching application methods were used (separately or combined) under greenhouse and field conditions. Chemical treatments recommended against ramulosis and water were used as controls. Under greenhouse conditions all strains reduced the disease incidence. While B. velezensis UFLA401 and P. lentimorbus MEN2 reduced the incidence by 56.6% and 45.7%, respectively, independent of the application method, B. amyloliquefaciens UFLA285 reduced the disease by about 60% when applied as a foliar spray or ST + foliar spray. Two field trials were performed and all bacterial strains reduced ramulosis incidence. In the first year, B. velezensis UFLA401 sprayed on the plants reduced incidence by 22.3% and ST + two foliar sprays resulted in the best performance, decreasing ramulosis by 57%. In both seasons the yield increased by using either bacterial or chemical treatments compared to the water control. The combination B. velezensis UFLA401 and P. lentimorbus MEN2 sprays provided better fiber quality than chemical treatment. Therefore, Bacillus sp. (UFLA285 and UFLA401) and P. lentimorbus MEN2 are potential tools to reduce ramulosis, increase cotton yield and fiber quality.

Bacillus amyloliquefaciens inoculation alters physiology of rice (Oryza sativa L. var. IR-36) through modulating carbohydrate metabolism to mitigate stress induced by nutrient starvation

To avoid disproportionate usage of chemicals in agriculture, an alternative eco-friendly strategy is required to improve soil fertility, and enhance crop productivity. Therefore, the present study demonstrates the role of plant beneficial rhizobacteria viz., Paenibacillus lentimorbus B-30488 (B-30488), Bacillus amyloliquefaciens SN13 (SN13), and their consortium in rice (Oryza sativa L. var. IR-36) facing nutrient deprivation. Parameters such as proline, total soluble sugar, relative water content, electrolytic leakage and malondialdehyde content were modulated in control rice seedlings as compared to treated under nutrient starved conditions. Bacterial inoculation not only significantly improved the agronomic parameters but also concentrations, uptake and partitioning of macro-micro nutrients. To disclose PGPR induced mechanisms to low nutrient stress tolerance, GC-MS analysis was performed. Overall 43 differential metabolites were characterized. Proline, glutamine, linolenic acid, malic acid, ribitol, propanoic acid and serine were accumulated in seedlings exposed to nutrient starvation. In PGPR inoculated rice glucose, fructose, mannose, glucitol, oleic acid, gulonic acid, raffinose, inositol were accumulated that induce metabolic and physiological parameters to reduce the impact of stress. Based on results SN13 was selected for gene expression analysis of metabolism-related genes that further affirmed the ability of PGPR to modulate carbohydrate metabolism in rice seedlings under suboptimum nutrient level.

Comparing the growth-promoting potential of Paenibacillus lentimorbus and Bacillus amyloliquefaciens in Oryza sativa L. var. Sarju-52 under suboptimal nutrient conditions

An adequate supply of mineral nutrients is crucial to obtain optimum productivity in agriculture. The present investigation was carried to find the inoculation effect of plant growth-promoting rhizobacteria (PGPR), i.e., Paenibacillus lentimorbus B-30488 (B-30488), Bacillus amyloliquefaciens SN13 (SN13) and their consortium for the growth of rice var. Sarju-52, grown under suboptimal nutrient conditions. The study revealed that the individual PGPR treatments showed comparatively better performance than consortia in morphological, physiological, biochemical, and nutrient analysis. Towards understanding the complex mechanism(s), untargeted metabolite profiling was performed using GC-MS, showed alteration of metabolites in rice seedlings facing suboptimal nutrient conditions and inoculated with PGPR. Metabolites such as oleic acid, mannitol, and ethyl iso-allocol were accumulated significantly under starved conditions. Under suboptimal nutrient conditions, sugars such as ribose, glucose, fructose, trehalose, palmitic acid, and myristic acid were accumulated significantly in PGPR inoculated seedlings. The significantly altered pathways due to PGPR inoculation under suboptimal nutrient conditions mainly belongs to carbohydrate and fatty acid metabolism. Interestingly, it was observed that among all the treatments, inoculation with SN13 performed comparatively better than other treatments. Further, in SN13 inoculated samples the qRT-PCR analysis of transcription factors and metabolism-related genes were validated that indicates PGPR deploy metabolic re-programming in rice var. Sarju-52 to enhance its nutrient use efficiency, tolerance, and growth under suboptimum nutrient conditions.

A multifaceted rhizobacterium Paenibacillus lentimorbus alleviates nutrient deficiency-induced stress in Cicer arietinum L.

Nutrient deficiency in soil is one of the limiting factors responsible for stunted growth and poor flowering/fruiting of crops which result in decline in overall agricultural productivity. However, one important strategy to overcome the problem of nutrient deficiency and to avoid use of chemical fertilizers is the use of plant growth promoting rhizobacteria (PGPR). Paenibacillus lentimorbus NRRL B-30488 (hereafter B-30488), an efficient PGPR has been reported to have various plant growth promoting traits that help crops to mitigate various environmental stresses. Therefore, the present work was designed to examine the application of B-30488 on chickpea growth under nutrient stress condition. Plants inoculated with B-30488 showed positive modulation in physio-biochemical behaviour and mineral nutrient uptake for better growth and development. Alteration in gene expression and metabolic profile under nutrient stress condition in chickpea also supported the stress amelioration capability of B-30488. Principal component analysis statistically proved that improved growth performance of chickpea plants under nutrient stress was mainly due to B-30488 induced modulation of metabolic pathways. To the best of our knowledge, this is the first study for analysis of growth promotion and stress alleviation in chickpea plants subjected to nutrient stress in presence of PGPR B-30488.

Paenibacillus lentimorbus induces autophagy for protecting tomato from Sclerotium rolfsii infection

During biotic stress, plants use several mechanisms to protect themselves that include the production of reactive oxygen species (ROS), induction of pathogenesis-related proteins and cell death. Some plant growth promoting rhizobacteria (PGPR) are known to act as bio-control agents that protect crops against pathogens. The biocontrol activity of PGPR Paenibacillus lentimorbus (B-30488) against Sclerotium rolfsii showed previously where several defense-related genes were upregulated with ROS induction in tomato. We further evaluate the other possibility, i.e. role of autophagy in enhancing defense in tomato using PGPR. Confocal microscopy revealed the presence of an acidotropic dye Mono Dansyl Cadaverine (MDC) stained autophagosomes in B-30488 treated healthy and infected plants. These autophagosomes almost disappeared in plants treated with an autophagy inhibitor chloroquine. The results were also confirmed by ultrastructural analysis of leaf tissues using transmission electron microscopy. Enhanced expression of autophagy-related genes was also monitored in B-30488 primed fungal infected tissues as compared to control by qRT-PCR. Results of ROS accumulation, fluorescence, confocal and transmission electron microscopy and gene expression analysis revealed induction of autophagy using B-30488 as a biocontrol agent suggesting a role in enhancing disease resistance in tomato. Overall, the present study indicated a role of B-30488 as a biocontrol in enhancing disease resistance in tomato and also assists a better understanding of fungal pathogenesis that is expected to be useful in developing new strategies for disease control.

PGPR in Managing Root Rot Disease and Enhancing Growth in Mandarin (Citrus reticulata Blanco.) Seedlings

Decline in general plant-health and fruit production in mandarin influenced by abiotic and biotic factors is a major threat to cultivars grown in Darjeeling and Sikkim hills. Fusarium root rot, caused by F. oxysporum, is one of the most serious diseases afflicted during early plant growth stage in Citrus. To address this, seven PGPR isolates - Pseudomonas poae (RMK03), Bacillus stratosphericus (RHS/CL-01), Ochrobactrum anthropi, Paenibacillus lentimorbus, Bacillus pumilus, Bacillus megaterium and Bacillus amyloliquefaciens were isolated from the rhizosphere of Citrus reticulata, C. limonia and Camellia sinensis, and used for evaluating their effect on growth of mandarin seedlings. Pseudomonas poae showed in vitro antagonism to Fusarium oxysporum. Better growth enhancement was noticed with P. poae, B. stratosphericus, O. anthropi and B. pumilus. Enhanced activity of chlorophyll, total protein, phenol, four major defense enzymeschitinase, β-1, 3-glucanase, peroxidase and phenyalanine ammonia lyase was observed upon application of PGPR. P. poae also suppressed root rot caused by Fusarium oxysporum. Use of PGPR, which promote growth besides reducing disease severity to some extent, may lead to use of eco-friendly approaches for controlling plant diseases.

Paenibacillus lentimorbus Inoculation Enhances Tobacco Growth and Extenuates the Virulence of Cucumber mosaic virus.

Previous studies with Paenibacillus lentimorbus B-30488” (hereafter referred as B-30488), a plant growth promoting rhizobacteria (PGPR) isolated from cow’s milk, revealed its capabilities to improve plant quality under normal and stress conditions. Present study investigates its potential as a biocontrol agent against an economically important virus, Cucumber mosaic virus (CMV), in Nicotiana tabacum cv. White Burley plants and delineates the physical, biophysical, biochemical and molecular perturbations due to the trilateral interactions of PGPR-host-CMV. Soil inoculation of B-30488 enhanced the plant vigor while significantly decreased the virulence and virus RNA accumulation by ~12 fold (91%) in systemic leaves of CMV infected tobacco plants as compared to the control ones. Histology of these leaves revealed the improved tissue’s health and least aging signs in B-30488 inoculated tobacco plants, with or without CMV infection, and showed lesser intercellular spaces between collenchyma cells, reduced amount of xyloglucans and pectins in connecting primary cells, and higher polyphenol accumulation in hypodermis layer extending to collenchyma cells. B-30488 inoculation has favorably maneuvered the essential biophysical (ion leakage and photosynthetic efficiency) and biochemical (sugar, proline, chlorophyll, malondialdehyde, acid phosphatase and alkaline phosphatase) attributes of tobacco plants to positively regulate and release the virus stress. Moreover, activities of defense related enzymes (ascorbate peroxidase, guaiacol peroxidase, superoxide dismutase and catalase) induced due to CMV-infection were ameliorated with inoculation of B-30488, suggesting systemic induced resistance mediated protection against CMV in tobacco. The quantitative RT-PCR analyses of the genes related to normal plant development, stress and pathogenesis also corroborate well with the biochemical data and revealed the regulation (either up or down) of these genes in favor of plant to combat the CMV mediated stress. These improvements led tobacco plant to produce more flowers and seeds with no negative impact on plant health. The present study may advocate the applicability of B-30488 for crop yield improvement in virus infested areas.

Southern blight disease of tomato control by 1-aminocyclopropane-1-carboxylate (ACC) deaminase producing Paenibacillus lentimorbus B-30488

abstractTomato cultivation is highly susceptible for soil born diseases and among them southern blight disease caused by Scelerotium rolfsii is very common. For its management use of chemical fungicides is not very successful as their spores are able to survive for many years in the soil. As an alternative eco-friendly approach to control the disease antagonistic microbes are being characterized.Among them plant growth promoting rhizobacteria Paenibacillus lentimorbus B-30488 (B-30488) with antagonistic properties, multiple PGP attributes stress tolerance and ACC deaminase enzyme activity is characterized to decipher its mode of action against S. rolfsii under in vitro and in vivo conditions. In vitro results obtained from this study clearly demonstrate that B-30488 has ability to show antagonistic properties under different abiotic stresses against S. rolfsii. Similar results were also obtained from in vivo experiments where B-30488 inoculation has efficiently controlled the disease caused by S. rolfsii and improve the plant growth. Deleterious enhanced ethylene level in S. rolfsii infected plants was also ameliorated by inoculation of ACC deaminase producing B-30488. The ACC accumulation, ACO and ACS activities were also modulated in S. rolfsii infected plants. Results from defense enzymes and other biochemical attributes were also support the role of B-30488 inoculation in ameliorating the biotic stress caused by S. rolfsii in tomato plants. These results were further validated by pathogen related gene expression analysis by real time PCR. Overall results from the present study may be concluded that ACC deaminase producing B-30488 has ability to control the southern blight disease caused by S. rolfsii and commercial bioinoculant package may be developed.

Screening of Endospore-Forming Bacteria for Cotton Seed Treatment against Bacterial Blight and Damping-off

Under conventional seed treatment, reports of efficacy loss or activity on nontarget microorganisms foster the search for sustainable disease management alternatives. Biological seed treatment has been meeting these requirements and exerts benefits that go beyond plant health. Looking for those alternatives, 368 Endospore-forming bacterial strains were screened for the control of bacterial blight and damping-off, caused by Xanhomonas axonopodis pv. malvacearum and Colletotrichum gossypii var. cephalosporioides, respectively. From the sampled sites, the strains with the highest bacterial blight and damping-off control were obtained from Primavera do Leste and Campo Verde (MT), respectively. Those had the potential to control both diseases were obtained from Primavera do Leste. Consistent disease control with seed treatment was found with two strains: Bacillus subtilis UFLA285 and Paenibacillus lentimorbus MEN2 with disease symptoms reduced by 45 and 56%, respectively for damping-off and 26 and 76%, respectively for bacterial blight. Therefore beneficial bacteria are a plausible alternative for a sustainable disease control in cotton.

Common bean growth and health promoted by rhizobacteria and the contribution of magnesium to the observed responses

Abiotic effects, such as nutrient abundance in soil, may interfere with the performance of plant-associated rhizobacteria in terms of plant physiology as well as disease control. We aimed to evaluate the effectiveness of rhizobacteria in the promotion of bean growth and nutrient uptake and the contribution of magnesium (Mg) supplementation to photosynthetic rates, CO2 assimilation, chlorophyll content, and bacterial wilt severity (Curtobacterium flaccumfaciens pv. flaccumfaciens). Bean plants from seeds treated with rhizobacteria were assessed for growth promotion-related variables, photosynthetic-related variables, as well as disease severity when plants were grown in soil with different magnesium contents (0–50mgkg−1). There was a 33–45% increase in root dry weight (Bacillus subtilis UFLA168* and B. amyloliquefaciens ALB629) and a 24–35% increase in relative growth index (B. subtilis UFLA285, UFLA168*, copper oxychloride, Paenibacillus lentimorbus MEN2). At 25mgkg−1 Mg, although the plant continued to take up Mg from the soil, increased accumulation of CO2 was found in the leaf mesophyll of both the ALB629 and control treatments, indicating low CO2 fixation and low Rubisco activity. Higher doses of Mg caused an increase in chlorophyll content as well as in photosynthetic rates in rhizobacterium-treated plants. Additionally, at 25mgkg−1 Mg, there was an increase in chlorophyll content in ALB629 (30%) and a reduction in bacterial wilt severity (51%). Moreover, photosynthesis was negatively correlated with disease severity (r=−0.53, P<0.01). Therefore, ALB629 is a promising bacterial strain to improve bean plant growth and nutrient uptake and reduce plant disease even under abiotic stress.

Insights from the draft genome of Paenibacillus lentimorbus NRRL B-30488, a promising plant growth promoting bacterium

Paenibacillus lentimorbus NRRL B-30488, a plant growth-promoting bacterium was isolated from Sahiwal cow's milk. The strain shows antagonism against phytopathogens, Fusarium oxysporum f. sp. ciceri and Alternaria solani. Its genome contains gene clusters involved in nonribosomal synthesis of secondary metabolites involved in antimicrobial activities. The genome sequence of P. lentimorbus NRRL B-30488 provides the genetic basis for application of this bacterial strain in plant growth promotion, plant protection and degradation of organic pollutants.

Paenibacillus lentimorbus B-30488r controls early blight disease in tomato by inducing host resistance associated gene expression and inhibiting Alternaria solani

The ability of Paenibacillus lentimorbus B-30488r (B-30488r) in reducing the early blight (EB) disease caused by Alternaria solani in tomato was assessed. Foliar application of the bacteria reduced the disease incidence by 45.3% as compared to control. In vitro studies indicated that B-30488r effectively reduces the radial growth of A. solani in dual culture, and SEM studies demonstrated complete degradation of fungal hyphae on co-culture with B-30488r. Both B-30488r and A. solani exhibited high similarity in the nutrient utilization of carbon sources present in tomato tissues. Changes in gene expression studied using RT-PCR analyses indicate significant up-regulation of defense and growth-related genes in tomato plants treated with B-30488r foliar spray and A. solani challenged plants pre-treated with B-30488r foliar spray. Principal component analysis results indicated that tomato plants treated with A. solani affected microbial community structure and population of the rhizosphere as compared to B-30488r. Results suggest that P. lentimorbus B-30488r has a multiple mode of action for its biological control activity by inducing resistance in tomato plants, by degrading the pathogen cell wall, and by competing for similar sources of nutrients on the phyllosphere. Additionally, B-30488r would not affect microbial populations on the rhizosphere of the tomato plants.

Induction of Paenibacillus lentimorbus biofilm by sodium alginate and CaCl2 alleviates drought stress in chickpea

Drought is a major environmental factor that limits chickpea production. An improvement in the adaption of crop to the fluctuating environmental conditions is therefore a major aim in chickpea breeding. However, the complexity of the trait has allowed only marginal progress. Our findings provide a solution to the current situation in the form of improved plant-growth-promoting effects caused by the biofilm formation of Paenibacillus lentimorbus B-30488 (B-30488) under water-limiting conditions. In vitro assays demonstrating the biofilm-forming ability of B-30488 and the factors enhancing it were studied. Greenhouse experiments were conducted for validating the in vitro results and assessing the effect of seed coating supplements in alleviating drought stress effects in chickpea seedlings. The chickpea seed bacterisation with B-30488 along with sodium alginate (1%) and CaCl2 (1 mM) caused an increase in germination percent and increased colony-forming units (CFU) of B-30488 in rhizosphere, resulting in amelioration of drought stress by positively influencing the dehydration-induced physiological responses. The whole study reflects a prospective role of sodium alginate and CaCl2 in influencing the biofilm formation of B-30488, and depicts the assistance of seed coating supplements in stress adaptation and protection of plants by alleviation of drought stress effects in chickpea without causing any major changes in the functional diversity of soil micro-organisms.

Paenibacillus lentimorbus enhances growth of chickpea (Cicer arietinum L.) in chromium-amended soil

Chromium (Cr), with its great economic importance in industrial use, is a major metal pollutant of the environment. It affects soil microbial activity and soil fertility, resulting in losses in yield of plants. Paenibacillus lentimorbus B-30488(r) (B-30488(r)) tolerated 200μgml(-1) of Cr under in vitro conditions and produced the plant growth promoting substance indole acetic acid in the presence of Cr. Our in vitro study indicates enhancement in B-30488(r) biofilm formation by sodium alginate (SA) and calcium chloride (CaCl(2)) both in absence and presence of supplemented Cr(VI) as compared to unsupplemented control. The plant growth promoting effects caused by the B-30488(r) biofilm in rhizosphere of chickpea under Cr(VI) stress suggests a phytoprotective role of B-30488(r) biofilm. Our study reflects the multifarious role of strain B-30488(r) and presents it as a potent plant growth promoting and bioremediation agent useful in Cr-contaminated rhizosphere soil, whereby the SA and CaCl(2) induced B-30488(r) biofilm on plant root acts as a shield in preventing the direct access of toxic Cr to plant tissues, thus reducing its uptake in plants.