Ramasamy Krishnamoorthy

The purpose of this study was to evaluate the impact of phyllosphere methylotrophic plant growth-promoting bacteria on drought stress mitigation in groundnut. The experiment included five treatments [T1 – Control, T2 – Methylobacterium populi TMV7-4, T3 – Methylobacterium thiocyanatum VRI7-A4, T4 – Pseudomonas psychrotolerans K-TMV7-6, and T5 – microbial consortium (comprising M. populi TMV7-4 + M. thiocyanatum VRI7-A4 + P. psychrotolerans K-TMV7-6)] under three water regimes (75%, 45%, and 20% field capacity). Each treatment was replicated five times, and pots were arranged in a completely randomized design. Seeds were sown in containers and maintained under regular watering for 22 days before imposing water stress for an additional 6 days. Plant growth parameters, proline content, and ethylene emission were recorded at the end of the stress period. In addition, the expression of the ACC oxidase (ACCO) gene was analyzed using qRT-PCR. Results revealed that microbial inoculation improved plant growth compared to the control, irrespective of drought stress intensity. However, no significant differences were observed between single strains and the microbial consortium. Microbial inoculation alleviated drought stress by reducing stress-related ethylene and proline accumulation, indicating lowered stress levels in treated plants. Across all drought conditions, plants inoculated with methylotrophic bacteria exhibited significantly reduced ACCO gene expression compared to the control. These methylotrophic isolates hold potential for development into a drought-tolerant bio-inoculant for groundnut.

Aim: This study aims to reveal the passenger endophytic bacterium Enterobacter cloacae S23 isolated from groundnut nodules and to underpin the molecular mechanism and genes responsible for abiotic stress tolerance. Background: A variety of microorganisms that contribute to nodulation and encourage plant development activity in addition to the nodulating Rhizobium. Passenger endophytes (PE) are endophytes that accidentally penetrate the plant without any selective pressure keeping them in the interior tissue of the plant. PE possesses characteristics that encourage plant development and boost output while reducing pathogen infection and improving biotic and abiotic stress tolerance. However, there is a lack of molecular evidence on the passenger endophyte-mediated alleviation of abiotic stresses. Objective: This study was formulated to reveal the draft genome sequence of Enterobacter cloacae S23, as well as genes and characteristics involved in plant growth promotion and stress tolerance. Method: The data were submitted to PATRIC and the TORMES-1.0 Unicyclker tools were used to conduct a complete genome study of Enterobacter cloacae S23. The TORMES-1.0 platform was used to process the reads. RAST tool kit (RASTtk) was used to annotate the S23 sequence. The plant growth-promoting traits such as indole acetic acid production, siderophore secretion, production of extracellular polysaccharides, biofilm formation, phosphate solubilization, and accumulation of osmolytes were examined under normal, 7% NaCl and 30% polyethylene glycol amended conditions to determine their ability to withstand salt and moisture stressed conditions, respectively. Result: We report the size of Enterobacter cloacae S23 is 4.82Mb which contains 4511 proteincoding sequences, 71 transfer RNA genes, and 3 ribosomal RNA with a G+C content of DNA is 55.10%. Functional analysis revealed that most of the genes are involved in the metabolism of amino acids, cofactors, vitamins, stress response, nutrient solubilization (kdp, pho, pst), biofilm formation (pga) IAA production (trp), siderophore production (luc, fhu, fep, ent, ybd), defense, and virulence. The result revealed that E. cloacae S23 exhibited multiple plant growth-promoting traits under abiotic stress conditions. Conclusion: Our research suggested that the discovery of anticipated genes and metabolic pathways might characterise this bacterium as an environmentally friendly bioresource to support groundnut growth through several mechanisms of action under multi-stresses.

Bio-inoculants (Biofertilizer) are an agricultural input that helps to keep the environment clean. By definition biofertilizers are efficient strains of isolated microorganisms that help plants grow in a variety of ways, both directly and indirectly. Biological nitrogen fixation, phosphate solubilization, phosphate mobilisation, siderophore generation and phytohormone production are some of the direct methods. The majority of efficient bio-inoculants perform better in laboratory conditions but fail to achieve the same results in the field. Due to the poor performance of bio-inoculants in field conditions, biofertilizers are not widely accepted by the farming community. Soil pH, temperature and chemical residues are considered as important abiotic stress. The key soil biotic elements are native microflora, predatory organisms and virus. Some bacteria are able to live despite the stress, but the total efficacy of the applied biofertilizer is diminished. Bio-inoculants must resist a variety of biotic and abiotic stresses in the soil, depending on the circumstances. We look at the obstacles that bio-inoculants confront in terms of survival and performance in the field.

Discharge of untreated wastewater is one of the major problems in various countries. The use of azo dyes in textile industries are one of the key xenobiotic compounds which effect both soil and water ecosystems and result in drastic effect on the microbial communities. Orathupalayam dam, which is constructed over Noyyal river in Tamil Nadu, India has become a sink of wastewater from the nearby textile industries. The present study had aimed to characterize the bacterial diversity and community profiles of soil collected from the vicinity of the dam (DS) and allied agricultural field (ALS) nearby the catchment area. The soil dehydrogenase and cellulase activities were significantly lower in DS compared to ALS. Additionally, the long-term exposure to azo dye compounds resulted in higher relative abundance of Saccharibacteria (36.4%) which are important for degradation of azo dyes. On the other hand, the relative abundance of Proteobacteria (25.4%) were higher in ALS. Interestingly, the abundance of Saccharibacteria (15.2%) were also prominent in ALS suggesting that the azo compounds might have deposited in the agricultural field through irrigation. Hence, this study revealed the potential bacterial phyla which can be key drivers for designing viable technologies for degradation of xenobiotic dyes.

This study isolated and determined the functional characteristics of bacterial flora associated with mealybug (Paracoccus marginatus) and their application as a bio-control agent. Second and fourth nymphal instars of the papaya mealybug were used for the isolation of the bacteria. These isolates were assessed for chitinolytic, protease, and glutathione S-transferase (GST) activities as well as mealybug wax degradation. An in vitro experiment was conducted with the most efficient isolates to control mealybugs reared on potato plants. A total of 102 bacterial isolates were obtained from the second (50 isolates) and fourth nymphal (52 isolates) stages of papaya mealybug. From these, 33 isolates were positive for chitinolytic activity, 25 isolates for protease, and 29 isolates showed glutathione S-transferase (GST) activity. In addition, 21 isolates were able to utilise mealybug wax as a carbon source. Regarding nutritional significance, the bacterial isolates exhibited nitrogen fixation, sulfur oxidation, as well as phosphate, zinc, and silica solubilisation. The application of bacterial isolates, Bacillus cereus PYP3, Bacillus sp. PLB1 and Serratia marcescens FLGB16 exhibited the highest mortality rates of 78.7%, 74.0%, and 69.3%, respectively on the second nymphal stage of papaya mealybug. Mealybug associated bacteria showed significantly higher mealybug mortality compared to antibiotics (kanamycin, carbenicillin, and spectinomycin) and commercial chemicals (profenophos and chlorpyrifos) used in this study. These efficient bacterial isolates may have the potential to control the mealybug under field conditions.

Polpass Arul Jose , Ramasamy Krishnamoorthy , Pandiyan Indira Gandhi , Murugaiyan Senthilkumar , Veeraran Jamahiraman , Karunandham Kumutha , Aritra Roy Choudhury , Sandipan Samaddar , Rangasamy Anandham and Tongmin Sa . J. Microbiol. Biotechnol. 2020;30:. https://doi.org/10.4014/jmb.2001.01016

A Gram-stain-negative, rod-shaped, aerobic bacterium, designated M2T2B2T, was isolated from fermented bovine products in Suwon, Republic of Korea. The strain displayed growth at 15–45 °C (optimum, 28–30 °C), pH 6.0–10.0 (pH 7.0) and 0–2 % (w/v) NaCl (0 %). Colonies were light pink-coloured, round and convex. The cells were positive for oxidase and weakly positive for catalase. The major fatty acids in whole cells of strain M2T2B2T were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), followed by summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), summed feature 2 (C12 : 0 aldehyde/unidentified 10.928/C14 : 0 3-OH/iso-C16 : 1 I), C16 : 0, C18 : 1 2-OH, C16 : 0 3-OH and C17 : 1 ω6c. The polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, and three unidentified aminolipids. Ubiquinone 10 was the predominant ubiquinone. The DNA G+C content was 68.0 mol%. The strain could fix atmospheric nitrogen, which was evaluated by the acetylene reduction assay. Further, whole genome sequence analysis revealed the presence of a nif gene cluster. Strain M2T2B2T showed the highest 16S rRNA, rpoD and nifH gene sequence similarity to members of the genus Azospirillum , and showed 97.6 % 16S rRNA gene sequence similarity to Azospirillum oryzae COC8T. The phenotypic, phylogenetic and genomic analyses support the proposal of strain M2T2B2T as being a novel species of the genus Azospirillum , for which the name Azospirillum ramasamyi sp. nov. is proposed. The type strain is M2T2B2T (=KACC 14063T=NBRC 106460T).