Application of Encapsulated Bacillus licheniformis Supplemented with Chitosan Nanoparticles and Rice Starch for the Control of Sclerotium rolfsii in Capsicum annuum (L.) Seedlings.

Rhizosphere encourages the survival and functioning of diverse microbial communities through the influence of plant roots. Likewise, the rhizobacterial functioning contribute to the growth and productivity of crop plants significantly. With the advancement of nanotechnology, the nanoparticles can expect to augment the performance of plant beneficial microorganisms including the rhizobacteria and hence have the promise to boost sustainable agricultural practices. In the present study, Bacillus licheniformis encapsulated in alginate-chitosan nanoparticles (CNPs) beads supplemented with rice starch (RS) has been evaluated for its plant growth enhancement and disease control properties. The encapsulated Bacillus licheniformis was initially characterized for indole-3-acetic acid (IAA) production, nitrogen fixing capacity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase production and antifungal activity against Sclerotium rolfsii. In addition to this, the plant growth promoting and biocontrol properties of the encapsulated Bacillus licheniformis were also evaluated using Capsicum annuum (L.) (chilli) seedlings. From the results, the plants treated with encapsulated Bacillus licheniformis supplemented with CNPs were found to have maximum growth enhancement. At the same time, plants treated with encapsulated Bacillus licheniformis supplemented with CNPs and RS were found to have enhanced disease suppression. This revealed the application of encapsulated Bacillus licheniformis supplemented with CNPs and RS as a promising delivery system for agricultural applications.

Evaluation of plant probiotic performance of Pseudomonas sp. encapsulated in alginate supplemented with salicylic acid and zinc oxide nanoparticles.

Plant growth promoting rhizobacteria (PGPR) are efficient candidates for the application in agricultural field to enhance the crop yield and to suppress the plant diseases. As the changes in agro-climatic conditions negatively affect the soil fertility and functioning of soil microbial community, there are significant demand for the innovative delivery methods for the PGPR to ensure its optimal performance. In the present study, Pseudomonas sp. DN18 has been entrapped in the alginate beads along with the supplemented salicylic acid (SA) and zinc oxide nanoparticles (ZnONPs). This modified formulation was further demonstrated for the IAA production and also antifungal activity against the Sclerotium rolfsii. In addition, superior plant growth promoting and biocontrol properties of the encapsulated Pseudomonas sp. DN18 supplemented with SA and ZnONPs have also been demonstrated on Oryza sativa seedlings by comparing with the free living Pseudomonas sp. DN18. This revealed the agricultural promises of Pseudomonas sp. DN18 encapsulated in a modified delivery system due to its functional superiority and stability over the free living bacteria based formulation.

Nanoelicitor based enhancement of camptothecin production in fungi isolated from Ophiorrhiza mungos.

In the study, endophytic fungi isolated from Ophiorrhiza mungos were screened for camptothecin (CPT) biosynthetic potential by high performance liquid chromatography (HPLC). Among the 16 fungi screened, OmF3, OmF4, and OmF6 were identified to synthesize CPT. Further LC-MS analysis also showed the presence of CPT specific m/z of 349 for the extracts from OmF3, OmF4, and OmF6. However, the fragmentation masses with m/z of 320, 305, 277 and 220 specific to the CPT could be identified only for the OmF3 and OmF4. These CPT producing fungi were further identified as Meyerozyma sp. OmF3 and Talaromyces sp. OmF4. The cultures of these two fungi were then supplemented with nanoparticles and analyzed for the quantitative enhancement of CPT production by LC-MS/MS. From the result, Meyerozyma sp. OmF3 was found to produce 947.3 ± 12.66 µg/L CPT, when supplemented with 1 µg/mL zinc oxide nanoparticles and the same for uninduced parental strain OmF3 was only 1.77 ± 0.13 µg/L. At the same time, Talaromyces sp. OmF4 showed the highest production of 28.97 ± 0.37 µg/L of CPT when cultured with 10 µg/mL silver nanoparticles and the same for uninduced strain was 1.19 ± 0.24 µg/L. The observed quantitative enhancement of fungal CPT production is highly interesting as it is a rapid and cost effective method. The study is remarkable due to the identification of novel fungal sources for CPT production and its enhancement by nanoparticle supplementation.

Type III polyketide synthase repertoire in Zingiberaceae: computational insights into the sequence, structure and evolution.

Zingiberaceae or 'ginger family' is the largest family in the order 'Zingiberales' with more than 1300 species in 52 genera, which are mostly distributed throughout Asia, tropical Africa and the native regions of America with their maximum diversity in Southeast Asia. Many of the members are important spice, medicinal or ornamental plants including ginger, turmeric, cardamom and kaempferia. These plants are distinguished for the highly valuable metabolic products, which are synthesised through phenylpropanoid pathway, where type III polyketide synthase is the key enzyme. In our present study, we used sequence, structural and evolutionary approaches to scrutinise the type III polyketide synthase (PKS) repertoire encoded in the Zingiberaceae family. Highly conserved amino acid residues in the sequence alignment and phylogram suggested strong relationships between the type III PKS members of Zingiberaceae. Sequence and structural level investigation of type III PKSs showed a small number of variations in the substrate binding pocket, leading to functional divergence among these PKS members. Molecular evolutionary studies indicate that type III PKSs within Zingiberaceae evolved under strong purifying selection pressure, and positive selections were rarely detected in the family. Structural modelling and protein-small molecule interaction studies on Zingiber officinale PKS 'a representative from Zingiberaceae' suggested that the protein is comparatively stable without much disorder and exhibited wide substrate acceptance.