Seed endophytic bacterium Lysinibacillus sp. (ZM1) from maize (Zea mays L.) shapes its root architecture through modulation of auxin biosynthesis and nitrogen metabolism.

Seed endophytic bacteria have been shown to promote the growth and development of numerous plants. However, the underlying mechanism still needs to be better understood. The present study aims to investigate the role of a seed endophytic bacterium Lysinibacillus sp. (ZM1) in promoting plant growth and shaping the root architecture of maize seedlings. The study explores how bacteria-mediated auxin biosynthesis and nitrogen metabolism affect plant growth promotion and shape the root architecture of maize seedlings. The results demonstrate that ZM1 inoculation significantly enhances root length, root biomass, and the number of seminal roots in maize seedlings. Additionally, the treated seedlings exhibit increased shoot biomass and higher levels of photosynthetic pigments. Confocal laser scanning microscopy (CLSM) analysis revealed extensive colonization of ZM1 on root hairs, as well as in the cortical and stellar regions of the root. Furthermore, LC-MS analysis demonstrated elevated auxin content in the roots of the ZM1 treated maize seedlings compared to the uninoculated control. Inoculation with ZM1 significantly increased the levels of endogenous ammonium content, GS, and GOGAT enzyme activities in the roots of treated maize seedlings compared to the control, indicating enhanced nitrogen metabolism. Furthermore, inoculation of bacteria under nitrogen-deficient conditions enhanced plant growth, as evidenced by increased root shoot length, fresh and dry weights, average number of seminal roots, and content of photosynthetic pigments. Transcript analysis indicated upregulation of auxin biosynthetic genes, along with genes involved in nitrogen metabolism at different time points in roots of ZM1-treated maize seedlings. Collectively, our findings highlight the positive impact of Lysinibacillus sp. ZM1 inoculation on maize seeds by improving root architecture through modulation of auxin biosynthesis and affecting various nitrogen metabolism related parameters. These findings provide valuable insights into the potential utilization of seed endophytic bacteria as biofertilizers to enhance plant growth and yield in nutrient deficient soils.

Functional characterization of 2-oxoglutarate-dependent dioxygenase gene family in chickpea.

Chickpea is an important leguminous crop plant with two cultivated types, desi and kabuli. It is nutritionally enriched in flavonoid content in addition to minerals and vitamins imparting huge health benefits to human beings. Our study elucidates the functionality of 2-oxoglutarate dependent dioxygenase (2-ODD) gene family members i.e., flavanone-3-hydroxylase (F3H), flavonol synthase (FLS) and anthocyanidin synthase (ANS) in chickpea using heterologous bacterial system and in-planta studies in Arabidopsis. This provides information about the biosynthesis of two very significant sub-classes of flavonoids- flavonols and anthocyanins. Here, we show that all the three homologs of F3H in chickpea can utilize not just naringenin but also eriodictyol as their substrate. Moreover, we show that FLS in chickpea exhibits bifunctionality having both FLS and F3H activity. Also, our study indicates the richness of desi chickpea over kabuli type through gene expression and metabolite content analyses. Overall, our study establishes the functionality of 2-ODD gene family involved in the early and late steps of flavonoid biosynthesis pathway in chickpea. It paves way for better genetic manipulation of the pathway for direct or indirect synthesis of three major subclasses of flavonoids (flavonol, anthocyanin and proanthocyanin) to develop nutritious, environmentally stable and healthy chickpea (Cicer arietinum) crop.

Endophytic Burkholderia: Multifunctional roles in plant growth promotion and stress tolerance.

The genus Burkholderia has proven potential in improving plant performance. In recent decades, a huge diversity of Burkholderia spp. have been reported with diverse capabilities of plant symbiosis which could be harnessed to enhance plant growth and development. Colonization of endophytic Burkholderia spp. have been extensively studied through techniques like advanced microscopy, fluorescent labelling, PCR based assays, etc., and found to be systemically distributed in plants. Thus, use of these biostimulant microbes holds the promise of improving quality and quantity of crops. The endophytic Burkholderia spp. have been found to support plant functions along with boosting nutrient availability, especially under stress. Endophytic Burkholderia spp. improve plant survival against deadly pathogens via mechanisms like competition, induced systemic resistance, and antibiosis. At the same time, they are reported to extend plant tolerance towards multiple abiotic stresses especially drought, salinity, and cold. Several attempts have been made to decipher the potential of Burkholderia spp. by genome mining, and these bacteria have been found to harbour genes for plant symbiosis and for providing multiple benefits to host plants. Characteristics specific for host recognition and nutrient acquisition were confirmed in endophytic Burkholderia by genomics and proteomics-based studies. This could pave the way for harnessing Burkholderia spp. for biotechnological applications like biotransformation, phytoremediation, insecticidal activity, antimicrobials, etc. All these make Burkholderia spp. a promising microbial agent in improving plant performance under multiple adversities. Thus, the present review highlights critical roles of endophytic Burkholderia spp., their colonization, alleviation of biotic and abiotic stresses, biotechnological applications and genomic insights.

Seed inhabiting bacterial endophytes of maize promote seedling establishment and provide protection against fungal disease.

Bacteria from different crops and plant varieties have been shown to possess enormous growth promotional attributes. The study aimed to investigate the role of the endophytic microbiome of seeds of corn in improving the growth of seedlings of two different varieties of maize crops (K-25 and baby corn). Furthermore, the study also assessed the role of these bacteria in the protection of seedlings from fungal pathogens. Total twenty-three endophytic bacterial strains were isolated from maize seeds and identified using 16S rDNA sequencing. Most of the isolates had the ability to synthesize auxin (70 %) and solubilize phosphate (74 %), while all the isolates showed nitrogen fixation ability. Some isolates also showed antagonistic activity against phytopathogenic fungi including Rhizoctonia solani and Fusarium sp. suggesting their biocontrol potential. The presence of different lipopeptide genes including bacillomycin D, fengycin, iturin A and surfactin was confirmed in some of the isolates. We observed that treating seeds with an antibiotic compromised the seedlings' growth; however, re-inoculation with endophytic isolates (ZM1/Lysinibacillus sp. and ZM2/Paenibacillus dendritiformis) restored the growth of the seedlings in terms of improved root and shoot development in comparison to non-inoculated controls. The colonization of inoculated bacteria on the root surface was visualized using fluorescent microscopy. Seedling protection assay showed that treated seeds (with ZMW8/ Bacillus velezensis) were protected from fungal infestation (Fusarium verticillioides) even after 12 days of inoculation in comparison to the uninoculated control. The study concludes that indigenous seed-associated bacteria of maize play a major role during seed germination, seedling formation and protect them from phytopathogens.

Seed Endophytic Bacteria of Pearl Millet (Pennisetum glaucum L.) Promote Seedling Development and Defend Against a Fungal Phytopathogen.

Seed endophytic bacteria (SEB) are primary symbionts that play crucial roles in plant growth and development. The present study reports the isolation of seven culturable SEB including Kosakonia cowanii (KAS1), Bacillus subtilis (KAS2), Bacillus tequilensis (KAS3), Pantoea stewartii (KAS4), Paenibacillus dendritiformis (KAS5), Pseudomonas aeruginosa (KAS6), and Bacillus velezensis (KAS7) in pearl millet seeds. All the isolates were characterized for their plant growth promoting activities. Most of the SEB also inhibited the growth of tested fungal phytopathogens in dual plate culture. Removal of these SEB from seeds compromised the growth and development of seedlings, however, re-inoculation with the SEB (Kosakonia cowanii, Pantoea stewartii, and Pseudomonas aeruginosa) restored the growth and development of seedlings significantly. Fluorescence microscopy showed inter and intracellular colonization of SEB in root parenchyma and root hair cells. Lipopeptides were extracted from all three Bacillus spp. which showed strong antifungal activity against tested fungal pathogens. Antifungal lipopeptide genes were also screened in Bacillus spp. After lipopeptide treatment, live-dead staining with fluorescence microscopy along with bright-field and scanning electron microscopy (SEM) revealed structural deformation and cell death in Fusarium mycelia and spores. Furthermore, the development of pores in the membrane and leakages of protoplasmic substances from cells and ultimately death of hyphae and spores were also confirmed. In microcosm assays, treatment of seeds with Bacillus subtilis or application of its lipopeptide alone significantly protected seedlings from Fusarium sp. infection.

Trending biocontrol strategies against Cronobacter sakazakii: A recent updated review.

Cronobacter sakazakii is an emerging foodborne pathogen, causing life-threatening infections in newborns and premature infants. Cronobacter spp. can survive under difficult processing conditions thereby contaminate the Powdered Infant Formula (PIF) during the manufacturing process. Infantile infections are associated with the consumption of contaminated PIF that was either contaminated intrinsically or extrinsically. This necessitates the development of sustainable strategies to manage the risk of Cronobacter infections. Natural methods of preservation holds promise as a viable alternative strategy to address the critical problem of emerging antimicrobial resistance and also to limit the negative effects of commonly used physico-chemical methods in food processing. The present study reviews the efficacies, potentials and developmental trends of biological antagonists and a combinatorial therapy to eliminate C. sakazakii using in vitro and in vivo methods. The mode of action of each biocontrol method has been discussed comprehensively. Most of these biocontrol agents interfere with the cell membrane integrity and its functions. However, none of the individual methods are able to eliminate the pathogen completely from the model food system i.e. reconstituted PIF. Each of the biological control strategies (agent) has its limitations in terms of their dose and method of application. A synergistic effect has been observed between the biological agent and physico-chemical treatments that may have the potential to ensure pathogen-free foods. Future research studies should evaluate the synergistic activities of these methods for their implication in infant foods as well as to understand the mechanisms of inactivation.

Physico-chemical characteristics and fibril-forming capacity of carp swim bladder collagens and exploration of their potential bioactive peptides by in silico approaches.

This study explores the sustainable valorization of carp swim bladder by-products. The high-value molecule collagens were successfully extracted from carp swim bladder with a yield of ∼60% (dry weight basis) and characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis, UV-spectrum and Fourier transform infrared spectroscopy. The extracted collagens showed the fibril-forming ability and high denaturation temperature (38-39°C). Furthermore, the extracted collagens subjected to preparing bioactive collagen hydrolysates with potential antioxidant activities. In vitro and In silico approaches (PepDraw, BIOPEP, PeptideRanker, Pepcalc and ToxinPred) were employed to evaluate the potential of carp collagens as a potential source of bioactive peptides. Furthermore, primary structure, biological potential, physicochemical, sensory and toxicity characteristics of the theoretically release antioxidative collagen peptides were predicted. Overall, the present study highlights the carp collagens hydrolysate could be a promising precursor of bioactive peptides for developing functional food or nutraceutical products.

Comparative assessment of physico-chemical characteristics and fibril formation capacity of thermostable carp scales collagen.

Collagen and collagen fibers have been widely documented as a potential and competitive biomaterial for medical applications. However, the searches for safe and realistic new collagen sources are still underway. Currently, fishery by-products (scales), a promising collagen source are usually discarded. In the present study, in vitro fibril-forming ability of the extracted fish scale collagen is reported. The aim of the investigation was to evaluate the concomitant comparison of fibril-forming abilities and characteristics of acid and pepsin soluble collagens from the scales of Indian major carp catla (Catla catla) and rohu (Labeo rohita). The extracted collagens were characterized as type I, with a total yield of 2.80-4.11% (w/w). Denaturation temperature determined for all collagens were between 35.9 and 37.7°C. All collagens exhibited high solubility in acidic pH and low NaCl concentrations. SEM clarified the lyophilized collagens and their fibril-forming capacity. Amino acid content and radical scavenging efficacy were also analyzed for the extracted collagen. The results revealed that extracted scale collagen from a renewable biological source could be used as biomaterials in various sectors. It might be suitable for preparing collagen gel for biomedical devices or as a scaffold for cell culture because of its high stability and fibril formation capacity.

Application of chitosan for improvement of quality and shelf life of table eggs under tropical room conditions.

The current investigation was conducted to study the effectiveness of chitosan coating in preserving the internal quality of table eggs stored under tropical room conditions of 32 ± 1 °C and 60-70 % r. h. Internal, physical and microbiological quality of eggs coated with chitosan was evaluated during 5-week storage at different temperature (22 ± 1 and 32 ± 1 °C). Chitin was extracted from shrimp processing raw byproducts and deacetylated to high quality chitosan. The prepared chitosan was analyzed for its characteristic properties. The chitosan with a viscosity of 2206 mPa.S was used to prepare the coating solution. The weight loss, Haugh unit, and yolk index values suggested that coating of eggs with shrimp α-chitosan increased the shelf life of eggs by almost 4-week at 22 ± 1 °C and 3-week at 32 ± 1 °C compared with controls (non chitosan coated and acetic acid coated) eggs. Three-time repeated coating was more effective in preserving the internal quality and preventing weight loss than with single-time coating of chitosan on egg. Therefore, three-time coating of eggs with 2206 mPa.S chitosan offer a protective barrier for preserving the internal quality of eggs stored at tropical room conditions and concomitantly prevent contamination with microorganisms.

Chitooligomers preparation by chitosanase produced under solid state fermentation using shrimp by-products as substrate.

Solid state fermentation (SSF) conditions were statistically optimized for the production of chitosanase by Purpureocillium lilacinum CFRNT12 using shrimp by-products as substrate. Central composite design and response surface methodology were applied to evaluate the effect of variables and their optimization. Incubation temperature, incubation time, concentration of inoculum and yeast extract were found to influence the chitosanase production significantly. The R(2) value of 0.94 indicates the aptness of the model. The level of variables for optimal production of chitosanase was 32 ± 1°C temperature, 96 h incubation, 10.5% (w/v) inoculum, 1.05% (w/w) yeast extract and 65% (w/w) moisture content. The chitosanase production was found to increase from 2.34 ± 0.07 to 41.78 ± 0.73 units/g initial dry substrate after optimization. The crude chitosanase produced 4.43 mM of chitooligomers as exclusive end product from colloidal chitosan hydrolysis. These results indicate the potential of P. lilacinum CFRNT12 for the chitosanase production employing cost effective SSF using shrimp by-products.

Comparative study on characteristics and in vitro fibril formation ability of acid and pepsin soluble collagen from the skin of catla (Catla catla) and rohu (Labeo rohita).

Catla (Catla catla) and Rohu (Labeo rohita) are the major carp fish produced by freshwater aquaculture in India. Processing of these carp fish generates potentially large quantities of by-products (waste) from non-edible fish parts by fish-processing factories and fish shops. The paper focuses on the extraction of the acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the skin of carp fish and subsequently their characteristics and in vitro fibril-forming ability. The extracted collagens are characterized as type I collagen based on the electrophoretic pattern. The denaturation temperature for all the collagens extracted was found to be 30.69-35.19°C by differential scanning calorimetry (DSC) analysis. The extracted collagens exhibited higher solubility at low concentration of NaCl (0-0.4M). All the ASC and PSC displayed different degrees of fibril-forming abilities and the scanning electron microscopy (SEM) analysis confirmed their well-defined fibril morphologies. The degree of collagen fibril formation was significantly (p≤0.05) higher (78%) in rohu skin collagen than catla skin collagen (36%). In general, the characteristics of two carp skin collagens were unique as evidenced by the electrophoretic, DSC, SEM and fibril-forming patterns. Overall, the results indicated the feasibility of using the carp skin as a good alternative source of realistic high-quality collagen.