Anurup Adak

Evaluating the efficacy of cyanobacterial formulations and biofilmed inoculants for leguminous crops

Our investigation was aimed towards evaluating the agronomic potential of biofilmed preparations (developed using Anabaena/Trichoderma as matrices with different agriculturally useful bacteria/fungi as partners) and selected cyanobacterial strains (Anabaena laxa (T7) RP8/Calothrix sp.). The formulations were prepared using paddy straw compost:vermiculite (1:1) as carrier and tested as inoculants in mungbean and soybean. The effects of the formulations were evaluated in terms of microbiological, nutrient availability, and plant biometric parameters. The Trichoderma viride–Bradyrhizobium biofilm exhibited 20–45% enhancement in fresh/dry weight of plants over other microbial treatments, while the T. viride–Azotobacter biofilm exhibited highest dehydrogenase activity in the soil and nitrogen fixation. T7 RP8 recorded statistically at par yield values with the T. viride–Bradyrhizobium (T5) biofilm treatment in mungbean. In soybean, among all the treatments, the T5 biofilm recorded the highest fresh weight of plants and available N in soil at harvest. The Anabaena–T. viride biofilmed formulations proved to be the most promising for soybean, recording 12–25% enhanced yield and microbial activity (measured as dehydrogenase activity). This study highlights the promise of cyanobacterial inoculants and biofilmed biofertilizers as promising inputs for integrated nutrient management strategies in agriculture.

PROSPECTING CYANOBACTERIA-FORTIFIED COMPOSTS AS PLANT GROWTH PROMOTING AND BIOCONTROL AGENTS IN COTTON

The potential of cyanobacteria-based compost formulations was evaluated in cotton crop at two agro-ecological locations (Nagpur and Sirsa) as plant growth promoting (PGP) and biocontrol agents. Compost-based formulations fortified with Calothrix sp. or Anabaena sp. enhanced germination and fresh weight of plants, and microbiological activity by 10–15%, besides increased available nitrogen (by 20–50%) in soil at Nagpur. In the fungi-infected fields at Sirsa, Anabaena – T. viride biofilmed formulation performed the best, recording 11.1% lower plant mortality than commercial Trichoderma formulation. Scanning electron microscopy confirmed the colonisation of inoculated cyanobacteria/biofilms on roots. Significant correlation between mortality, increased activity of hydrolytic enzymes and fresh weight of plant roots were recorded. Calothrix sp. and Anabaena sp. proved promising as both PGP and biocontrol agents, while biofilmed formulations substantially reduced mortality of cotton plants in sick plots. This study illustrates the promise of cyanobacteria as viable inoculation option for integrated nutrient and pest management strategies of cotton.

Micronutrient enrichment mediated by plant-microbe interactions and rice cultivation practices

ABSTRACT A field experiment was conducted to evaluate the effect of different plant growth promoting microorganisms (PGPM) on micronutrient enrichment of rice crops grown under conventional (flooded) and SRI (System of Rice Intensification) practices. Significant differences were recorded among treatments and cultivation practices in terms of soil microbial activity reflected in enhanced nutrient uptake, enzyme activity, and yield. The Anabaena-based biofilm inoculants were particularly superior under both methods of cultivation, leading to 13–46% enhancement of iron and 15-41% enhancement of zinc in rice grains over uninoculated controls. SRI was found to be superior in terms of enhancing the concentration of zinc, copper, iron, and manganese (Zn, Cu, Fe and Mn), particularly in grains, and significant in increasing the activity of defense- and pathogenesis- related enzymes and yield parameters. This study illustrates the utility of cyanobacteria-based inoculants for both methods of rice cultivation and their significant interactions with the plant, leading to micronutrient enrichment of rice grains. Such formulations can complement the current biofortification strategies and help in combating the problems of malnutrition globally.

Prospecting plant growth promoting bacteria and cyanobacteria as options for enrichment of macro- and micronutrients in grains in rice–wheat cropping sequence

Abstract The influence of plant growth promoting bacteria (PGPB) and cyanobacteria, alone and in combination, was investigated on micronutrient enrichment and yield in rice–wheat sequence, over a period of two years. Analysis of variance (ANOVA) in both crops indicated significant differences in soil dehydrogenase activity and micronutrient enrichment in grains (Fe, Zn in rice, and Cu, Mn in wheat). The combined inoculation of Anabaena oscillarioides CR3, Brevundimonas diminuta PR7, and Ochrobactrum anthropi PR10 (T6) significantly increased nitrogen, phosphorus, and potassium (NPK) content and improved rice yield by 21.2%, as compared to the application of recommended dose of NPK fertilizers (T2). The treatment T5 (Providencia sp. PR3 + B. diminuta PR7 + O. anthropi PR10) recorded an enhancement of 13–16% in Fe, Zn, Cu, and Mn concentrations, respectively, in rice grains. In wheat, Providencia sp. PW5 (T6) recorded the highest yield (5.23 Mg ha−1) and significantly higher enrichment of Fe and Cu (44–45%) in the grains. This study highlighted the promise of combinations of cyanobacteria/bacteria and their synergistic action in biofortification and providing savings of 40–60 kg N ha−1. Future focus needs to be towards integrating such promising environment-friendly and environmentally sustainable options in nutrient management strategies for this cropping sequence.

Prospecting cyanobacterial formulations as plant-growth-promoting agents for maize hybrids

Cyanobacteria represent environment-friendly inputs that can lead to savings of nitrogenous fertilisers, in addition to improving plant growth and soil fertility. The present investigation aimed to evaluate the potential of cyanobacteria inoculants as nutrient-management and plant-growth-promoting options for maize hybrids, which require high inputs of fertilisers. Four types of inoculants comprising consortia of cyanobacteria or cyanobacterium–bacterium and biofilmed preparations using Anabaena were evaluated for 11 maize hybrids. The microbial inoculants performed significantly better than the uninoculated control by bringing about 10–15% enhancement in Soil Plant Analysis Development (SPAD) value, plant height and available nitrogen (N) in the soil, which also led to a saving of 40 kg N ha−1. An additional enrichment of 40–50 kg N ha−1 in the soil was recorded in the treatments A1 (Anabaena–Providencia formulation) and A3 (Anabaena–Trichoderma biofilmed formulation). The cyanobacterial formulations A4 (Anabaena–Azotobacter biofilmed formulation) and A3 in conjunction with B10 (PMH-1), B8 (Bio-9681) and B9 (HM-8) proved to be superior associations. This is the first report on identification of promising cyanobacteria–maize genotype combinations as plant-growth-promoting and N-saving options. These results emphasise the significance of including cyanobacteria formulations in integrated nutrient management practices for this fertiliser-intensive crop.

Microbial priming elicits improved plant growth promotion and nutrient uptake in pea

Legume–microbial interactions focus mainly on Rhizobium. The present study aimed to evaluate the plant growth-promoting (PGP) potential of bacterial and cyanobacterial formulations and variety-specific differences following their inoculation in two varieties of pea (Pisum sativum L.), namely Arkel and GP-17. Providencia sp. PW5–Anabaena laxa CW1 treatment was the most promising, with an 11%–76% increase in defense enzyme activity in both varieties. Interestingly, Arkel responded better in terms of nitrogenase activity, which was enhanced several-fold in the inoculated treatments, and exhibited a significant correlation (r = 0.787, 0.778, 0.755; p < 0.05) with shoot length, fresh weight and nodule number per plant, respectively. Nodule number was significantly correlated (r = 0.74, 0.81; p < 0.05) with PAL and PPO activity, respectively, and with microbial biomass carbon, alkaline phosphatase and dehydrogenase activity (r = 0.582, 0.538, 0.666; p < 0.05), respectively. Variety GP-17, however, responded bet...

Simultaneous saccharification and fermentation of alkali-pretreated corncob under optimized conditions using cold-tolerant indigenous holocellulase

The present investigation was aimed towards pretreatment optimization of corncob to maximize cellulose and hemicellulose recovery, followed by substrate selection for holocellulase production using psychrotolerant Aspergillus niger SH3. Dilute alkali pretreatment (1.5% NaOH) resulted in higher recovery of cellulose (59.66%) and hemicellulose (28.34%) from corncob, while corn stover proved to be the best substrate for holocellulase production. Further, saccharification was optimized by Box-Behnken design to select the suitable conditions for maximum sugar release from pretreated corncob. The optimum conditions for maximum sugar release were 8% (w/v) substrate loading, 11 FPU/gds enzyme loading at temperature 38 °C and pH 3.0 which resulted in 114.5% higher sugar yield (912 mg/gds of pretreated biomass) as compared with un-optimized conditions (425.35 mg/gds). Theoretical yield of 48.8% ethanol was achieved through simultaneous saccharification and fermentation (SSF) using pretreated corncob. This study illustrates the potential of different corn residues as a promising substrate for bioethanol production.

Taxonomic and functional diversity of the culturable microbiomes of epigeic earthworms and their prospects in agriculture.

Eisenia foetida and Perionyx excavatus are potent vermicomposting earthworms having immense importance in organic matter recycling under tropical conditions, particularly in India. Comparative assessment of the cultivable gut microbiome of these two epigeic earthworms after growth on lignocellulosic biomass, revealed populations of 3.2–8.3 × 109 CFU. Diversity analyses using 16S rDNA sequences revealed that the major dominating classes were Firmicutes (50–60%), followed by Actinobacteria (26.7–33%), and Alphaproteobacteria (5.6–6.7%). Despite exhibiting similar diversity indices and species richness, Betaproteobacteria (6.7%) and Gammaproteobacteria (11.1%) were solely present in E. foetida and P. excavatus, respectively. A set of 33 distinct morphotypes, including 18 from E. foetida and 15 from P. excavatus were selected. Carbohydrate utilization profiles generated using Hi‐Carbo™ kits revealed that the isolates from the gut of P. excavatus – Arthrobacter pascens IARI‐L13 and Bacillus subtilis IARIC were able to utilize 54 and 51.4% of the carbohydrates tested. Sorbose was not utilized, while unusual carbohydrates – adonitol and methyl‐d‐mannoside were utilized only by members from the gut of P. excavatus, while melizitose was utilized by those uniquely by E. foetida microbiome. Functional characterization revealed that β‐glucosidase activity was most prevalent in the culturable microbial community. Alkaline and acid phosphatase activity was more widespread in the E. foetida gut microbiome. All the culturable gut bacterial isolates produced ammonia, but IAA was detected only in five cultures. The unique functional attributes of the two culturable microbiomes, grown on a similar diet, reveals the significance of proper selection of earthworm substrate combinations for effective vermicomposting.

Bioethanol Production Scenario in India: Potential and Policy Perspective

Energy crisis has become a fundamental issue over mankind across the globe. To meet the energy demand for transport, blending of bioethanol with gasoline has been mandated in India like several other developing and developed countries. Moreover, in spite of urbanisation and industrial development, agriculture sector has long been the backbone of Indian economy. Currently in India, sugarcane molasses is being used for the production of bioethanol but cannot fulfil the demand of ethanol for blending targets. Therefore, the surplus crop residues may be explored for second-generation biofuel to meet the demand for alternative and renewable energy sources. However, the national policy on biofuels has no clear long-term mandated targets and penalties to ensure its successful execution. To safeguard the long-term sustainability and economic viability of Indian bioethanol market, it is indispensable to diversify the feedstock basket and gain insights from the reality of pilot-scale studies. India’s present bioethanol production scenario can be boosted by introduction of new low-cost technology for the bioconversion of lignocellulosics. This chapter is a comprehensive analysis of the future of bioethanol market in India based on biomass availability, policy barriers and perspectives along with the possible solutions.