Baljeet Singh Saharan

Identification of multi-trait PGPR isolates and evaluating their potential as inoculants for wheat

Development of an effective plant growth promoting rhizobacteria (PGPR) inoculant necessitates the presence of a diverse set of traits that can help its colonization of the rhizosphere and survival under varying environmental conditions. In our investigation, a set of 100 bacterial isolates from the rhizosphere of wheat plants were screened initially on the basis of a seed germination assay; ten bacterial isolates (AW1–AW10) were selected. These isolates were then tested in vitro for specific PGPR traits, such as the production of IAA, siderophore, ammonia, HCN, P solubilization, ACC deaminase activity, acetylene reduction assay and antifungal activity. Of the ten isolates, AW5 was found to be promising for all PGP attributes. An experiment undertaken in the controlled conditions of the National Phytotron Facility revealed the potential of three isolates (AW1, AW5 and AW7) in enhancing the growth parameters of wheat plants. Characterization of these isolates using polyphasic approaches involving both phenotypic and genotypic attributes led to their identification as Bacillus sp. (AW1), Providencia sp. (AW5), and Brevundimonas diminuta (AW7), respectively. These strains could prove effective PGPR inoculants as they possess a number of traits useful for their establishment and proliferation in soil. The genus Providencia is reported for the first time for its PGP potential, using cultural as well as functional attributes to show its suitability as an inoculant for wheat crop.

Biotechnological Production of Polyhydroxyalkanoates: A Review on Trends and Latest Developments

Polyhydroxyalkanoates (PHA) producers have been reported to reside at various ecological niches which are naturally or accidently exposed to high organic matter or growth limited conditions such as dairy wastes, hydrocarbon contaminated sites, pulp and paper mill wastes, agricultural wastes, activated sludges of treatment plants, rhizosphere, and industrial effluents. Few among them also produce extracellular by-products like rhamnolipids, extracellular polymeric substances, and biohydrogen gas. These sorts of microbes are industrially important candidates for the reason that they can use waste materials of different origin as substrate with simultaneous production of valuable bioproducts including PHA. Implementation of integrated system to separate their by-products (intracellular and extracellular) can be economical in regard to production. In this review, we have discussed various microorganisms dwelling at different environmental conditions which stimulate them to accumulate carbon as polyhydroxyalkanoates granules and factors influencing its production and composition. A brief aspect on metabolites which are produced concomitantly with PHA has also been discussed. In conclusion, exploring of capabilities like of dual production by microbes and use of wastes as renewable substrate under optimized cultural conditions either in batch or continuous process can cause deduction in present cost of bioplastic production from stored PHA granules.

Enhancing micronutrient uptake and yield of wheat through bacterial PGPR consortia

A pot experiment was undertaken under net house conditions, with three rhizobacterial strains AW1 (Bacillus sp.), AW5 (Providencia sp.) and AW7 (Brevundimonas sp.), applied along with 2/3 recommended dose of nitrogen (N) and full dose of phosphorus (P) and potassium (K) fertilizers (N90P60K60). An enhancement of 14–34% in plant biometric parameters and 28–60% in micronutrient content was recorded in treatments receiving the combination of AW1 + AW5 strains, as compared to full dose of fertilizer application. The treatment involving inoculation with AW5 + AW7 recorded highest values of % P and N, with a two-fold enhancement in phosphorus and 66.7% increase in N content, over full dose application of P and K fertilizers. A significant correlation was recorded between plant biomass, panicle weight, grain weight, N, P and iron (Fe) with acetylene reduction activity, indicating the significance of N fixation in overall crop productivity. Our study illustrates the multiple benefits of plant growth promoting rhizobacteria (PGPR) inoculation in integrated nutrient management and biofortification strategies for wheat crop.

Simultaneous Production of Biosurfactants and Bacteriocins by Probiotic Lactobacillus casei MRTL3

Lactic acid bacteria (LAB) are ubiquitous and well-known commensal bacteria in the human and animal microflora. LAB are extensively studied and used in a variety of industrial and food fermentations. They are widely used for humans and animals as adjuvants, probiotic formulation, and dietary supplements and in other food fermentation applications. In the present investigation, LAB were isolated from raw milk samples collected from local dairy farms of Haryana, India. Further, the isolates were screened for simultaneous production of biosurfactants and bacteriocins. Biosurfactant produced was found to be a mixture of lipid and sugar similar to glycolipids. The bacteriocin obtained was found to be heat stable (5 min at 100°C). Further, DNA of the strain was extracted and amplified by the 16S rRNA sequencing using universal primers. The isolate Lactobacillus casei MRTL3 was found to be a potent biosurfactant and bacteriocin producer. It seems to have huge potential for food industry as a biopreservative and/or food ingredient.

Production and Structural Characterization of Lactobacillus helveticus Derived Biosurfactant

A probiotic strain of lactobacilli was isolated from traditional soft Churpi cheese of Yak milk and found positive for biosurfactant production. Lactobacilli reduced the surface tension of phosphate buffer saline (PBS) from 72.0 to 39.5 mNm−1 pH 7.2 and its critical micelle concentration (CMC) was found to be 2.5 mg mL−1. Low cost production of Lactobacilli derived biosurfactant was carried out at lab scale fermenter which yields 0.8 mg mL−1 biosurfactant. The biosurfactant was found least phytotoxic and cytotoxic as compared to the rhamnolipid and sodium dodecyl sulphate (SDS) at different concentration. Structural attributes of biosurfactant were determined by FTIR, NMR (1H and 13C), UPLC-MS, and fatty acid analysis by GCMS which confirmed the presence of glycolipid type of biosurfactant closely similar to xylolipids. Biosurfactant is mainly constituted by lipid and sugar fractions. The present study outcomes provide valuable information on structural characterization of the biosurfactant produced by L. helveticus MRTL91. These findings are encouraging for the application of Lactobacilli derived biosurfactant as nontoxic surface active agents in the emerging field of biomedical applications.

Biodegradation and detoxification of melanoidin from distillery effluent using an aerobic bacterial strain SAG5 of Alcaligenes faecalis

Distillery effluent retains very dark brown color even after anaerobic treatment due to presence of various water soluble, recalcitrant and coloring compounds mainly melanoidins. In laboratory conditions, melanoidin decolorizing bacteria was isolated and optimized the cultural conditions at various incubation temperatures, pH, carbon sources, nitrogen sources and combined effect of both carbon and nitrogen sources. The optimum decolorization (72.6 ± 0.56%) of melanoidins was achieved at pH 7.5 and temperature 37 °C on 5th day of cultivation. The toxicity evaluation with mung bean (Vigna radiata) revealed that the raw distillery effluent was environmentally highly toxic as compared to biologically treated distillery effluent, which indicated that the effluent after bacterial treatment is environmentally safe. This proves to be novel biological treatment technique for biodegradation and detoxification of melanoidin from distillery effluent using the bacterial strain SAG(5).

Functional characterization of biomedical potential of biosurfactant produced by Lactobacillus helveticus

Highlights • Isolation of biosurfactant producing lactic acid bacteria.• Antiadhesive potential of the lactic acid derived biosurfactants against biofilm forming pathogens.• Stability studies of biosurfactants.

Biosurfactants of Lactic Acid Bacteria

The Lactic acid bacteria (LAB), commonly associated with food and feed fermentation normally be inherent in the mucosal surfaces of healthy humans and animals. Microbial surface active agents are amphiphilic compounds produced commonly by microorganisms predominately bacteria and yeast on their cell surface, or extracellularly with exceptional surface and emulsifying activities. The physiological function of microbial surfactants in a producer cell is not entirely understood. On the contrary, there has been hypothesis about their involvement in emulsification of water insoluble substrates. Dissimilar to chemical surfactants, which are categorized according to the nature of their polar grouping, biosurfactants are categorized largely by their chemical composition and their microbial origin. Recent advances in biological disciplines and analytical approaches have focused about the enormous rise in biosurfactant for applications in environmental, bio medicine, food/feed, and cosmetics industries. The demand for novel biosurfactants in the cosmetics, food and pharmaceutical formulations, is progressively increasing and the biosurfactants with effective and eco-friendly composition, impeccably meet this demand. Most of the biosurfactant-producing microorganisms are pathogenic and challenging to handle in commercial formulations. The development of biosurfactant production from nonpathogenic microorganisms such as “Biosurfactant derived from LAB” is a prevailing task that is receiving increased attention in direction to escape pathogenicity. Detailed studies of their natural roles in microbial interactions, cell signaling, pathogenicity, and biofilm development could advocate significant future applications.

Evaluation of Brevibacillus brevis as a potential plant growth promoting rhizobacteria for cotton (Gossypium hirsutum) crop.

The present investigation was undertaken to isolate, screen and evaluate a selected promising PGPR Brevibacillus brevis on cotton crop. Out of 156 bacterial isolates one of the most promising isolate was analyzed for the various PGP traits. A seed germination analysis was conducted with cotton seeds to evaluate the potential of the isolate to promote plant growth. The bacterial isolate was checked for its growth and survival at high temperatures. The isolate was also analyzed for the PGP traits exhibited after the heat treatment. To identify the isolate morphological, biochemical and molecular characterization was performed. The isolate was found positive for many of the PGP attributes like IAA, ARA, anti-fungal activity and ammonia production. Effect of seed bacterization on various plant growth parameters was used as an indicator. The isolate showed significant growth and exhibited various PGP traits at high temperature making it suitable as an inoculant for cotton crop. Isolate was identified as Brevibacillus brevis [SVC(II)14] based on phenotypic as well as genotypic attributes and after conducting this research we propose that the B. brevis which is reported for the first time for its PGP potential in cotton, exerts its beneficial effects on cotton crop through combined modes of actions.

Structural Properties of Biosurfactants of Lab

Unlike surfactants of chemical origin, which are characterized according to their nature, biosurfactants are generally characterized mostly by their chemical composition and origin. Biosurfactants are composed of hydrophilic moiety (polar, head) containing of amino acids, peptides, polysaccharides; and hydrophobic moiety (nonpolar tail) composed of fatty acids. The main cause that confines its commercialization is the inadequate knowledge of structural composition, so as to limiting its application as pharmaceuticals and therapeutic agents. Generally, biosurfactants obtained from LAB are found as multicomponent mixtures composed of polysaccharides, lipids, phosphate groups, and proteins. Structural properties are vital to design customized biosurfactants based on specific applications. Still, only inadequate information is available in the literature related to the biosurfactants derived from the LAB. Development in advanced chromatographic techniques, enhanced purification of the biosurfactant, and production from simpler medium could lead to determine structurally purified biosurfactants for future applications in food and therapeutics formulations.