Accomplishments

  • The Division of Microbiology pioneered the development and commercialization of biofertilizers (Rhizobium, Azotobacter, Azospirillum, phosphate solubilizers, AM fungi and BGA) that provided the input for practicing organic agriculture in India.
  • The preparation and quality control of peat based Rhizobium inoculants have been standardized for the first time in India at the Division. Infact the pioneering efforts of the Division of Microbiology in this direction have catalysed several agricultural Universities in India to start production and distribution of Rhizobium inoculants on a large scale.
  • Survey and isolation of root nodule bacteria in Indian soils have provided unique data in the occurrence and distribution of native strains of Rhizobium for several important leguminous crops. As a consequence Rhizobium maps had been prepared for different legumes.

  • Actual amounts of nitrogen fixation by chickpea (Cicer arietinum) plants were up to 62 kg N ha-1 under field conditions, determined using the isotope [(15NH4)2SO4] dilution method in the International Atomic Energy Agency (IAEA,Vienna) coordinated project with involvement of Brazil, Egypt, Greece and Pakistan. This seminal finding led to the popularisation of biofertilizers for many crop plants in our country.
  • Mass production of Rhizobium inoculants for pulse crops was initiated in the late 1960s. Indian peat based inoculants of IARI were comparable to Nitragin inoculants and as a consequence, their imports from USA ceased in 1969.
  • The Division developed Arbuscular Mycorrhizal inoculum for all crops especially horticultural crops and nursery grown vegetables and commercialized under the trade name ‘Nutrilink’. It mobilizes phosphorus and trace elements like zinc, iron, copper, cobalt, magnesium, molybdenum.

  • The ‘Blue-Green Algal biofertilizer’ technology, standardised for mass production and improved for energetic efficiencies and economics, is popular among rice farmers
  • Long-term algalization in rice fields showed that yield increases were up to 29% with a gain of 25-30 kg N ha-1 per season. The ‘Blue-Green Algal biofertilizer’ technology, standardised for mass production and improved for energetic efficiencies and economics, is popular among rice farmers.
  • Microbial consortia were developed using efficient strains of Trichoderma viride, Aspergillus nidulans, Phanerochaete chrysosporium, and Aspergillus awamori for quality improvisation and accelerated composting.

 

 

 

 

  • First time, potassium solubilising bacteria were isolated from various extremes environments of high salinity and high temperature. Database of 152 bacteria with an ability to solubilise K was prepared. The promising cultures may be employed as inoculants for sustainable crop production. Besides, a new method was developed for tentative identification of K solubilizer by using dyes in the medium that show change in colour due to acid production.

  • Many biocontrol agents active against plant pathogenic fungi were identified; Paenibacillus polymyxa HKA-15 showed higher inhibitory action against Xanthomonas campestris pv. phaseoli, probably involving a lipopeptide (1347 Da). Streptomyces albus suppressed different soil borne plant pathogenic fungi. Bacillus subtilis RP 24, a promising plant growth promoting rhizobacterium and a potent biocontrol agent, was isolated and characterized using molecular tools. HPLC and LC MS analyses revealed presence of iturin, fengysin and surfactin in cell-free extracts; iturin operon presence was also confirmed by the PCR based assay.
  • The Division provided the first report on Proteus vulgaris and Kurthia as plant growth promoting rhizobacteria.
  • A technology was developed for biological delignification of paddy straw using Myrothecium roridum LG 7, Trametes hirsuta and Streptomyces griseorubens for removal of lignin and improved sachharification for 2nd generation bioethanol production.

 

 

 

  • A consortium of fungi and bacteria was developed for in-situ degradation of rice and wheat biomass after harvesting of crops.

 

 

  • Technology have been developed for the mass multiplication of Chlorella sorokiniana for algal biodiesel production
  • Cyanobacteria react to salt stress through osmotic adjustments, sequestering inorganic ions or secretion of excess polysaccharides.  Reclamation of saline soils with cyanobacteria with gypsum at the 50% or 75% recommended dose gave comparable yield benefits in rice and wheat to that of the gypsum at the recommended dose.
  • Organic farming experiments in rice based cropping system through microbial inputs were conducted. In Kharif, Basmati rice (Pusa basmati 1121) grown organically with four inputs (BGA, Azolla, Vermicompost and FYM) gave the highest rice grain yield (4.72 t/ha) which was followed by INM (4.58 t/ha) and chemical fertilization (4.36 t/ha). Yield of different vegetables was also significantly higher under organic farming compared to chemical fertilization but was at par with INM.
  • Liquid bioinoculants for Azotobacter chroococcum and phosphate solubilizing bacteria with a shelf-life of 30 months were developed. The technology was licensed and commercialized.
  • First report on the cyanobacterial colonization of the roots of wheat, and improvements in its growth and yield when combined with bacterial inoculants was provided.

 

 

  • Strains of Anabaena inhibited the growth of Pythium debaryanum and Pythium aphanidermatum. Gene(s) involved in the fungicidal activity in Anabaena laxa RPAN8 and Calothrix elenkinii RPC1 belong to the novel endoglucanases belonging to families - peptidase M20 and GH5.

  • Novel enteric bacterial strain (identified as Serratia marcescens) showed the capability for biosurfactant production, catechol dioxygenase activity as well as polycyclic aromatic hydrocarbon (PAH) degradation. Similarly, results of HPLC analysis confirm PAH degradation potential of an actinomycete, Streptomyces rochei PAH-13 and a fungal strain, Phanerochaete chrysosporium VV-18.  These three microbes namely, Serratia marcescens PAH-L11, Streptomyces sp. PAH-13 and Phanerochaete chrysosporium VV-18 were selected for development of consortia for   in vitro PAH-degradation.

  • Superoxide dismutase gene was PCR amplified from cyanobacterial isolate SL-8 and validated in E. colifor imparting tolerance to salt stress. Two cyanobacterial isolates (SL16 and SL17) and one isolate (SL6) obtained from Sambhar salt lake showed PCR amplification of genes encoding 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase and ecotoine respectively. The DAHP synthase amplicon was sequenced and BLAST results showed similarity with DAHP synthase gene of Lyngbya, Synechocystis and Cyanothece.

 

  • Organic farming experiments in rice based cropping system through microbial inputs were conducted. In Kharif, Basmati rice (Pusa basmati 1121) grown organically with four inputs (BGA, Azolla, Vermicompost and FYM) gave the highest rice grain yield (4.72 t/ha) which was followed by INM (4.58 t/ha) and chemical fertilization (4.36 t/ha). Yield of different vegetables was also significantly higher under organic farming compared to chemical fertilization but was at par with INM.
  • EM consortium was developed using indigenous isolates of yeast, lactic acid bacteria, photosynthetic bacteria fungal and actinomycete strains namely Phanerochaete chrysosporium VV18, Streptomyces sp. C3, Rhodotorula glutinisY6, Lactobacillus plantarum, and a strain of photosynthetic bacteria. It could produce a good quality compost with high humus content and a C:N ratio of 15:1 within 90 days.

  • Microbes were identified for conversion of lignocellulosic biomass into ethanol. The lignolytic fungi Myrothecium roridum LG7 and Trametes hirsuta were able to delignify the paddy straw within short incubation time without consuming cellulose during biopretreatment. The effect of these fungion structural components revealed their efficiency for removal of lignin from biomass thereby improving the enzymatic hydrolysis potential of substrates. This reflects the higher sugar yield in biopretreated biomass within 24 hr of saccharification. Furthermore, new cellulolytic microbes were isolated from nature for production of indigenous cellulase cocktail for saccharification mainly to reduce the cost of bioethanol production from LC biomass.
  • First reports on hydrolytic enzyme(s) mediated fungicidal activity in strains of Anabaena against phytopathogenic fungi (Pythium sp., Fusarium sp, Rhizoctonia sp.) and gene(s) for novel chitosanases and novel endoglucanases identified in  Anabaena laxa, Anabaena fertilissima and and Calothrix elenkinii .

 

  • Development of synergistic combinations of cyanobacteria-bacteria for biofortification of rice and wheat, improved soil N and P mobilization and enhanced crop yields

 

  • Novel compost based formulations developed using promising cyanobacterial strains showed effective biocontrol potential in tomato. First reports on defense enzymes and their role in biocontrol and cyanobacterial colonization of roots of wheat and tomato using SEM analyses.

 

  • Microalgae with high lipid content were identified for production of biodiesel.  Nutrient modulation strategy using nitrogen limitation along with glucose (mixotrophy) recorded 31% lipids in MIC-G5 Chlorella sp after 14d.

 

  • Among various metabolic intermediates and sugars evaluated, glucose (39.16%) and tryptophan (38.8%) enhanced the lipid productivity of Chlorella sp. FAME profiles revealed significant reduction in the content of Poly unsaturated fatty acids (PUFA) and enhanced Mono unsaturated fatty acids (MUFA) (especially oleic acid) in the treatments involving tryptophan.
  • Harvesting procedures for microalgae standardized using inorganic as well as organic flocculants. FAME profile provided an evidence regarding suitability of Chlorococcum spand Chlorella sp in the area of biofuel production from microalgae.
  • A set of thermotolerant strains isolated from hot springs of Manikaran and Bakreshwar (India) were selected with an aim to isolate dnak gene which encodes DnaK/Hsp70 protein. The dnak gene from Bacillus pumilus strain B3 was successfully cloned and sequenced. The gene was successfully expressed in Escherichia coli BL 21 (DE3) using pET expression systems and it allowed the growth of E. coli up to 50 °C and survival up to 60 °C for 16 hours, suggesting that dnak gene imparts tolerance to host cells under high temperature.



    a. Protein molecular mass marker; b. E.coli transformant (uninduced); c. E.coli transformant induced (cell lysates collected 1 hr after induction); d. E.coli transformant induced (cell lysates collected immediately after induction)

 

  • Genomic library of Phormidium was constructed and screened for NaCl tolerance. Sequence analysis of the insert from two clones that showed tolerance to 3% NaCl showed strong homology with MAP Kinase and a hypothetical protein.
  • Bacillus licheniformis proteins up-regulated under salt stress were identified as alpha-ketoglutarate decarboxylase (mol wt. 106.6 kDa, PI 5.96 ), aminotransferase class IV YjlD (mol wt. 41.88 kDa, PI 6.21), general stress protein YfkM (mol wt. 18.66 kDa, PI 4.90),  ribosomal proteins S4 (mol wt. 22.89 kDa, PI 9.95) and L5 (mol wt. 20.25, PI 9.67).

 

  • Superoxide dismutase gene was amplified and sequenced (583 bp). It showed 98% similarity with Bacillus licheniformis sodA gene. It was successfully cloned in expression vector pET 29. Transformed E. coli strain BL21 containing expression vector pET 29 with cloned sodA gene was able to grow at 7.5% NaCl while untransformed E. coli strain BL21 was unable to grow.

 

  • Secretome analysis of a hypercellulolytic Streptomyces sp. was carried out. Of the 82 proteins detected through LC MS/MS analysis of Secretome of the Streptomyces sp. ssr198, 32 were enzymes belonging to different glycoside hydrolase families and showed variations in molecular weight, pI and functions. Multiple endoglucanases and xylanases with diverse molecular weights were detected in the zymogram. It was found that besides multiple holocellulolytic enzymes it also contains many other industrially important enzymes like chitinase, laminarinase, zinc metalloprotease and superoxide dismutase.
  • Development of a strategy to produce cellulases through cloning and expression of β-1, 4-endoglucanase gene from Bacillus subtilis:A strain of Bacillus subtilis IARI-SP-1 isolated from soil long term irrigated with effluents of paper and pulp mill showed high β-1,4-endoglucanase (2.5 IU/ml) activity. A full length gene of β- 1, 4-endonuclease consisting of 1499 nucleotides was amplified and identified through sequence analysis of the amplified product. The ORF encoded for a protein of 500 amino acids with a predicted molecular weight of 55 kDa. The gene was cloned in pET-28a and over expressed in Escherichia coli BL21 (DE3). In comparison to wild strain (B. subtilis), the transformed E. coli exhibited four times increase in cellulase production. Higher enzyme activity was observed in supernatant (8.2 IU/ml) than cell pellet (2.8 IU/ml) suggesting more extracellular production of β-1, 4-endoglucanase. SDS-PAGE and CMC plate assay also confirmed the overproduction by the transformed E. coli. This is being currently exploited for the overproduction of cellulase by harvesting it on larger scale and using it as cellulase preparations for hydrolysis of lignocellulosic biomass.

 

  • A consortium of Ensifer adhaerens (PCP 4), Pseudomonas putida (PCP 1) and Lysinibacillus fusiformis (PCP 156) was developed and validated for PCP degradation in soil. The detection of intermediates during 30 days incubation confirmed degradation of PCP. Hence, this consortium can be tested further at larger scale to strengthen the findings of the study.
  • Phospho-compost was prepared from paddy straw amended with cattle manure/ poultry manure/ farm yard manure, each added separately as nitrogen source. The composting mixture was inoculated with phytate mineralizing fungal consortium consisting of Aspergillus and Trichoderma. The three types of composts with phosphorus (P) content ranging from 0.7-1.0 % and C: N ratio of 15- 16.4:1 was evaluated for their agronomic performance under wheat cultivation. At 120 days of crop growth, individual compost improved the availability status of soil P by 21 % compared with chemical fertilization (CF). The three different composts improved the organic carbon content of soil by 15-20 % compared with chemically fertilized soil. The experimental results exhibited that application of phospho-compost can save 35-40 % of chemical P input without compromising with the wheat crop yield.

 

  • Yeast cultures isolated from vegetable waste and spoiled fruit juice and identified as Rhodotorula and Candida by 16SrDNA sequencing were found to be superior β-glucosidase producers. The extracellular β-glucosidase produced had specific activity of 0.0531 as compared to the cell associated fraction (Enzyme activity- 0.071 IU/ml, Specific activity- 1.05) when grown on M9 minimal media supplemented with carboxy methyl cellulose (CMC 1%) and yeast extract (0.1%). One of the most significant finding of this study was the glucose tolerance ability of the β-glucosidase enzyme obtained from Rhodotorula.