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This paper discusses the outcome of a study on the transition of cyanobacterial biofertilizer technology from laboratory to small-scale production to large-scale commercial use. The nitrogen-fixing ability of cyanobacteria helps to reduce the dose of chemical nitrogen fertilizer (urea) needed, so they are immensely important for paddy crops, especially in Southeast Asian nations, where soil quality is deteriorating and where large groups of farmers cannot afford the use of more costly chemical fertilizers. Inundated water is required for this technology to be effective in paddy crops and is also imperative for good paddy crop; fortunately, this is exactly how paddy is grown on the Indian subcontinent. This study elaborates the whole cyanobacterial biofertilizer technology chain and its development process, the triggering role played by industry partners, and industry’s dissemination of the technology to farmers’ doorsteps.

Phycobiliproteins (PBPs) of cyanobacteria and algae possess unique light harvesting capacity which expand the photosynthetically active region (PAR) and allow them to thrive in extreme niches where higher plants cannot. PBPs of cyanobacteria/algae vary in abundance, types, amino acid composition and in structure as a function of species and the habitat that they grow in. In the present review, the key aspects of structure, stability, and spectral properties of PBPs, and their correlation with ecological niche of cyanobacteria are discussed. Besides their role in light-harvesting, PBPs possess antioxidant, anti-aging, neuroprotective, hepatoprotective and anti-inflammatory properties, which can be used in therapeutics. Recent developments in therapeutic applications of PBPs are reviewed with special focus on '

Microalgae are photosynthetic eukaryotes that serve as microbial cell factories for the production of useful biochemicals, including pigments. These pigments are eco-friendly alternatives to synthetic dyes and reduce environmental and health risks. They also exhibit excellent anti-oxidative properties, making them a useful commodity in the nutrition and pharmaceutical industries. Light-harvesting pigments such as chlorophylls and phycobilins, and photoprotective carotenoids are some of the most common microalgal pigments. The increasing demand for these pigments in industrial applications has prompted a need to improve their metabolic yield in microalgal cells. So far, expensive cultivation methods and sensitivity to microbial contamination remain the main obstacles to the large-scale production of these pigments. This review highlights current issues and future prospects related to the production of microalgal pigments. The review also emphasizes the use of engineering approaches such as genetic engineering, and optimization of media components and physical parameters to increase their commercial-scale production.

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Rhizosphere is a rich repository of plant growth promoting rhizobacteria (PGPR) which is a sustainable tool to increase crop productivity and maintain soil health. In this context, 43 isolates were obtained on Jensen’s medium from the rhizosphere of Triticum aestivum, Zea mays, Solanum tuberosum, Aloe barbadensis and Bacopa monnieri grown in Palampur, (Himachal Pradesh) India. Out of these isolates, only six isolates (WT-A2, WT-A1, MZ-A2, PT-A1, PT-A3 and BM-A3) exhibited significantly higher nitrogenase activity (451.45, 441.58, 440.91, 444.02, 383.64 and 374.44 nmole C2H4 h−1 mg−1 protein) as compared to the reference strain of Azotobacter chroococum MTCC 446 (372.85 nmole C2H4 h−1 mg−1 protein). The isolate WT-A2 was the most efficient with respect to nitrogenase activity (451.45 nmole C2H4 h−1 mg−1 protein), indole acetic acid production (17.45 μg ml−1), ammonia production and siderophore production. Isolate WT-A2 was identified as Stenotrophomonas rhizophila on the basis of morphological, biochemical and 16S rRNA sequence analysis. In order to prepare liquid bioinoculant formulation, survivability studies on S. rhizophila was carried out in four different liquid carriers (Compost Tea, Biogas slurry, Vermiwash and Minimal Growth Medium) at room temperature (average maximum temp. was 23.83 °C and average minimum temp. was 11.91 °C). The results showed that S. rhizophila survived better in different liquid carriers (9.873 log cfu ml−1 in biogas slurry; 9.843 log cfu ml−1 in vermiwash; 9.163 log cfu ml−1 in minimal growth medium), and Compost Tea was the best carrier to support higher bacterial load (9.907 log cfu ml−1) on 180th day of storage. The results are of practical importance as this (compost tea) liquid carrier could be used to produce liquid biofertilizer formulation. Also, S. rhizophila could be a potential biofertilizer candidate as it posses multifarious plant growth promoting traits.

Modern agricultural practices are relying excessively upon the use of synthetic fertilizers to supply essential nutrients to promote crop productivity. Though useful in the short term, their prolonged and persistent applications are harmful to soil fertility and nutrient dynamics of the rhizospheric microbiome. The application of nanotechnology in form of nanofertilizer provides an innovative, efficient, and eco-friendly alternative to synthetic fertilizers. The nanofertilizers allow a slow and sustained release of nutrients that not only supports plant growth but also conserve the diversity of the beneficial microbiome. Such attributes may help the phytomicrobiome to efficiently mitigate both biotic and abiotic stress conditions. Unfortunately, despite, exceptional efficiency and ease of applications, certain limitations are also associated with the nanofertilizers such as their complicated production process, tenuous transport and dosage-sensitive efficiency. These bottlenecks are causing a delay in the large-scale applications of nanofertilizers in agriculture. This review aims to highlight the current trends and perspectives on the use of nanofertilizers for improving soil fertility with a special focus on their effects on beneficial phyromicrobiome.

Eukaryotic microalgae are a rich source of commercially important metabolites including lipids, pigments, sugars, amino acids and enzymes. However, their inherent genetic potential is usually not enough to support high level production of metabolites of interest. In order to move on from the traditional approach of improving product yields by modification of the cultivation conditions, understanding the metabolic pathways leading to the synthesis of the bioproducts of interest is crucial. Identification of new targets for strain engineering has been greatly facilitated by the rapid development of high-throughput sequencing and spectroscopic techniques discussed in this review. Despite the availability of high throughput analytical tools, examples of gathering and application of proteomic and metabolomic data for metabolic engineering of microalgae are few and mainly limited to lipid production. The present review highlights the application of contemporary proteomic and metabolomic techniques in eukaryotic microalgae for redesigning pathways for enhanced production of algal metabolites.

Fusarium wilt (FW), caused by Fusarium udum Butler (FU), is among the challenging factors in the production of pigeonpea. Therefore, exploring a superior pigeonpea genotype from landraces or local cultivars through the selection of innate resistance to FW using different biological and molecular approaches, and validating its resistance response, could be an alternative to sustainable crop improvement. Five distinct pigeonpea genotypes, with resistant (ICP2894) and susceptible (ICP2376) controls, were selected on the basis of the incidence percentage of FW, from three different states of India. Among them, the cultivar Richa, which displayed low incidence of FW (10.0%) during the genotype evaluation, was further examined for its innate resistance to FW. Molecular characterization of antioxidant (AO) enzyme [APX and SOD] and pathogenesis-related (PR) protein [CHS and b-1, 3-glucanase] families were performed. The obtained results of reverse transcription-polymerase chain reaction-based expression study and in silico analysis showed a higher level of induction of PR and AO genes, and the strong interaction of their putative proteins with fungal cellobiohydrolase-c protein established their antifungal activity, conferring early plant defense responses to FU in Richa. Our study demonstrated a strong and combinatorial approach involving biological assay, molecular experiments, and in silico analysis to identify a superior pigeonpea genotype that was resistant to FW across a major biogeographic region.

The versatile use of biopigments in food, feed, cosmetic, pharmaceutical and analytical industries emphasized to find different and renewable sources of biopigments. Microalgae, including cyanobacteria, are becoming a potential candidate for pigment production as these have fast-growing ability, high pigment content, highly variable and also have "Generally recognized as safe" status. These algal groups are known to produce different metabolites that include hormones, vitamins, biopolythene and biochemicals. We discuss here the potential use of microalgal biopigments in our daily life as well as in food and cosmetic industries. Pigment like carotenoids has many health benefits such as antioxidant, anti-inflammatory properties and also provide photo-protection against UV radiation. This review details the effect of various abiotic and biotic factors such as temperature, light, nutrition on maximizing the pigment content in the microalgal cell. This review also highlights the potential of microalgae, whether in present native or engineered strain including the many metabolic strategies which are used or can be used to produce a higher amount of these valuable biopigments. Additionally, future challenges in the context of pigment production have also been discussed.

Microalgae gained attention as eco-friendly, sustainable, and potential sources of various bioactive compounds. These have distinctive capability to synthesize and produce a wide range of compounds especially biopigments along with CO2 fixation capabilities. Biopigments are the essential components of light harvesting complex of microalgae. These accessory pigments (carotenoids and phycobiliproteins) have their primary role in light harvesting but they also have photo-protective role during excess light energy. During recent times, the demands of these biopigments are on the rise due to their great biological potential and beneficial effect on human health. These biopigments show wide range of beneficial applications such as antioxidant, anti-cancerous, anti-inflammatory, immunomodulatory etc. These are also utilized in industries such as food, cosmetic, and pharmaceutical. In this chapter, we discuss about the prospective microalgae as a source of various biopigments and their application in various commercial areas as well as their unique properties. In addition, various challenges and bottleneck in the production of microalgal biopigments are also summarized along with the efforts to explore recent biotechnological approaches applied on microalgae in enhancing biopigments production.

Microalgae have been developed as a potential source for many high-value biochemicals, pigments, and biomolecules. These products have a very important role in various industries such as pharmaceutical, nutraceutical, cosmetic, and food. They are also a promising source for oil as well as biofuel production. In recent years, microalgae have gained more scientific attention as modern approaches allow a more precise understanding of the basic metabolic processes. Synthetic biology is an emerging field in biological sciences, which allows us to manipulate the living system according to our goods and benefits. Various industries that have benefitted from the use of synthetic biology include food, pharmaceutical, agriculture, bio-energy, etc. This chapter includes various aspect of synthetic biology applied to microalgae for improving the capability of these microalgal cells to produce different commercial products. Despite limited knowledge and lack of optimal tools, there are many reports of successful production of carbohydrates, lipids, alcohols, terpenoids, and phenylpropanoids, etc. through microalgae. This shows us that synthetic biology has tremendous application in microalgae-based product production.

Background: Pigeonpea [Cajanus cajan (L.) Millsp.] is a major dietary protein source to a large vegetarian population in the world. However, Fusarium wilt (FW) caused by Fusarium udum Butler (FU) is one of the challenging factors to pigeonpea production. FW resistance in pigeonpea is restricted to specific agro-climatic zones. Therefore, exploring a superior pigeonpea genotype from landraces or local cultivars cultivated in various rural regions and validating its resistance response at biological and molecular level could be an alternative to crop improvement program. The present study was carried out to identify superior genotypes of pigeonpea through selection of innate resistance to FW using different biological and molecular approaches.Result: Five distinct genotypes of pigeonpea along with well-known one resistant (ICP2894) and susceptible (ICP2376) control were selected on the basis of percentage of FW disease incidence from three different states of India after an extensive survey work. Among them, Richa had shown very less FW incidence (10.0%) under genotype evaluation study and was further selected for experimental validation at molecular level for its innate resistance to FW. Molecular characterization and expression profiling of biotic stress responsive genes representing antioxidant enzymes (APX and SOD) and Pathogenesis related proteins (CHS and β-1,3-glucanase)families were carried out. Under FU challenged conditions in Richa, expression patterns of both AO genes found to be similar, while expression of both PR genes was gradually increased with inoculation time. Putative 3D protein structure of CHS and SOD were generated. Molecular docking with fungal effect or protein cellobio-hydrolase-c (CBH-c) also revealed that their role in blocking the hydrolytic activity of CBH-c during pathogen invasion. Conclusion: The obtained results of expression study and in-silico analysis showed that the higher level of induction of PR and AO genes and strong interaction of their putative proteins with fungal CBH-cprotein established their antifungal activity conferring early plant defense responses to restrict the pathogen growth in resistant genotype Richa. Our study displaying a strong and combinatorial approach involving biological assay, molecular experiment and in-silico analysis to identify a superior genotype of pigeonpea resistant to FW across a major biogeographic region.

The cyanobacterial phycobiliproteins (PBPs) are an important natural colorant for nutraceutical industries. Here, a multi-objective hybrid machine learning-based optimization approach was used for enhanced cell biomass and PBPs production simultaneously in Nostoc sp. CCC-403. A central composite design (CCD) was employed to design an experimental setup for four input parameters, including three BG-11 medium components and pH. We achieved a 61.76% increase in total PBPs production and an almost 90% increase in cell biomass by our prediction model. We also established a test genome-scale metabolic network (GSMN) for Nostoc sp. and identified potential metabolic fluxes contributing to PBPs enhanced production. This study highlights the advantage of the hybrid machine learning approach and GSMN to achieve optimization for more than one objective and serves as the foundation for future efforts to convert cyanobacteria as an economically viable source for biofuels and natural products.

The production of phycobiliproteins (PBPs) from cyanobacteria represents both the industrial application and their commercial value. In this study, the capability of Anabaena variabilis CCC421 for the production of PBPs was evaluated which was further improved by optimization of selected BG-11 medium components viz. FAC, K2HPO4 and trace metals. A design matrix approach using evolutionary algorithm comprised of genetic-algorithm (GA) and fuzzy-logic-methodology (FLM), i.e., GA-Fuzzy, was used for the optimization. The maximum production of PBPs obtained with combinatory approach of GA-Fuzzy was 408.5 mg/L at an optimum combination of factors (FAC 0.153 g/L, K2HPO4 0.2 g/L and Trace metals 0.5 ml/L) which was a 2.13 fold more than the control medium. This novel approach is very useful for modulating biological processes since various nutrients and metabolites have greater influence on these processes.

The focus of the current study is to assess the impact of blue green algae (BGA) technology on farming practices and economic conditions of farming households. The states of Punjab, Uttar Pradesh and Haryana considered as major rice-growing states of India were chosen for the primary survey. It was observed that use of BGA resulted in 25.2% of urea reduction with an overall 3.8% increase in the yield and a marginal decrease in per acre cultivation cost. Tobit model has been used to identify the determinants of increasing cropping area under BGA. Factors such as age, education, operated land holdings and leased-in land have a positive and significant impact on area under BGA. The study also provided the comparative analysis on yield of paddy, urea consumption and income with and without BGA application. It was observed that farmers earned about 3% greater income along with 41.1% reduction in dosage of urea while reaping 1% higher yield of paddy.

Cyanobacteria are the oxygenic photosynthesis performing prokaryotes and show a connecting link between plastids of eukaryotic autotrophs and prokaryotes. A variety of pigments, like chlorophyll, carotenoids and phycobiliproteins which exhibit different colors are present in cyanobacteria. Increasing consciousness about the harmful effects of synthetic or chemical dyes encouraged people to give more preference towards the usage of natural products, such as plant or microbial-derived colors in food and cosmetics. That is why cyanobacteria are exploited as a source of natural colors and have high commercial value in many industries. This review mainly focuses on different cyanobacterial pigments, their applications and modern biotechnological approaches such as genetic engineering, systems biology to enhance the production of biopigments for their potential use in pharmaceuticals, food, research, and cosmetics industries.

Chlorella sp. MCC 7 and Botryococcus sp. MCC 31 were investigated to enable large-scale biodiesel production from minimal constituents in the growth medium. Response surface methodology (RSM) was used to maximise the biomass productivity and lipid yield using only nitrogen (N), phosphorus (P) and potassium (K) as urea, single super phosphate and muriate of potash. The optimum values were 0.42 g/L nitrogen; 0.14 g/L phosphorus and 0.22 g/L potassium for Chlorella sp.; and 0.46 g/L; 0.14 g/L and 0.25 g/L for Botryococcus sp. Lipid yield of 42% for Chlorella sp. and 52% in Botryococcus sp. was observed. An enhancement in lipid yield by approximately 55% for Chlorella sp. and 73% for Botryococcus sp. was registered as compared to original nutrient medium. Fourier transform infrared (FTIR) analysis of extracted lipids revealed characteristic bands for triglycerides. This study provided utilisation of a practicable nutrient recipe in the form of N, P, K input for enhanced lipid yield from the selected microalgal strains.

Nostoc is a diverse genus of filamentous cyanobacteria with tremendous potential for agricultural and industrial applications. Morphometric methods and routine 16S rDNA-based identification undermines the genetic diversity and impedes strain-level differentiation. A comparative study to deduce the discriminatory power of random amplified polymorphic DNA (RAPD) and amplified ribosomal DNA restriction analysis (ARDRA) for analyzing the genetic diversity of 20 Nostoc strains of diverse geographical origin was carried out. The RAPD primer used in the study generated 100% polymorphic profile. HIP TG primer produced the highest number of bands and fragments. Five primers, viz. OPA 08, OPA 11, HIP GC, OPAH 02 and OPF 05 could produce unique bands for 11 strains. Cluster analysis using the RAPD profile showed 12.5–25% similarity among the strains. Following in silico restriction analysis, two restriction enzymes, viz. HaeIII and HinfI were selected for ARDRA. However, clustering based on the restriction pattern showed 22.5–100% similarity. Results of the present study clearly indicate higher resolution of RAPD which can be reliably used for strain-level differentiation of Nostoc strains.

Algae constitute a diverse group possessing immense morphological and metabolic diversity. Besides chlorophyll, algal cells contain a number of accessory pigments like carotenoids and phycobiliproteins that help in photosynthesis and protect the cells from photo bleaching. These brilliantly colored pigments have several industrial and biotechnological applications in food, cosmetic, diagnostic, and pharmaceutical industries due to their nontoxic, noncarcinogenic nature and additional health-promoting effects like antioxidative and immune-boosting properties. The excellent photophysical properties, rich nutritional value, antioxidant nature, and presence of antiaging compounds in algae have resulted in its application in cosmetic and skin-care products. Increasing number of clinical researches on health benefits of algal metabolites and pigments have also made them a safe and viable replacement of chemically synthesized drugs. Further insight into the biological properties of these molecules and their mode of action will help in development of efficient and targeted products to protect human skin against increasing environmental threats.

Nanohexaconazole is a highly efficient fungicide against Rhizoctonia solani. Nanoparticles are alleged to adversely affect the non-target organisms. In order to evaluate such concern, the present study was carried out to investigate the effect of nanohexaconazole and its commercial formulation on sensitive nitrogen fixing blue green algae (BGA) and bacteria. Various activities of algae and bacteria namely growth, N-fixation, N-assimilation, Indole acetic acid (IAA) production and phosphate solubilization were differently affected in the presence of hexaconazole. Although, there was stimulatory to slightly inhibitory effect on the growth measurable parameters of the organisms studied at the recommended dose of nanohexaconazole, but its higher dose was inhibitory to all these microorganisms. On the other hand, the recommended as well as higher dose of commercial hexaconazole showed much severe inhibition of growth and metabolic activity of these organisms as compared to the nano preparation. The uses of nanohexazconazole instead of hexaconazole as a fungicide will not only help to control various fungal pathogens but also sustain the growth and activity of these beneficial microorganisms for sustaining soil fertility and productivity.

The present investigation was carried out to decipher the interplay between paraquat (PQ) and exogenously applied nitric oxide (NO) in Azolla microphylla. The addition of PQ (8 μM) increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) by 1.7, 2.7, 3.9 and 1.9 folds respectively than that control in the fronds of Azolla. The amount of H2O2 was also enhanced by 2.7 times in the PQ treated plants than that of control. The supplementation of sodium nitroprusside (SNP) from 8–100 μM along with PQ, suppressed the activities of antioxidative enzymes and the amount of H2O2 compared to PQ alone. The drop in the activity of antioxidative enzymes — SOD, GPX, CAT and APX was highest (39.9%, 48.4%, 41.6% and 41.3% respectively) on the supplementation of 100 μM SNP with PQ treated fronds compared to PQ alone. The addition of NO scavengers along with NO donor in PQ treated fronds neutralized the effect of exogenously supplied NO. This indicates that NO can effectively protect Azolla against PQ toxicity by quenching reactive oxygen species. However, 200 μM of SNP reversed the protective effect of lower concentration of NO donor against herbicide toxicity. Our study clearly suggests that (i) SNP released NO can work both as cytoprotective and cytotoxic in concentration dependent manner and (ii) involvement of NO in protecting Azolla against PQ toxicity.

Two diazotrophic cyanobacteria, Westiellopsis prolifica and Anabaena variabilis were evaluated for elucidating the possible mechanism of mineral phosphate solubilization. Phosphate starved cyanobacteria evaluated for the presence of organic acids, extracellular compounds or enzymes that might have been produced and promoted the mineral phosphate solubilization with Mussorie Rock Phosphate and Tricalcium Phosphate as substrates. Both the cultures did not reveal production of organic acids throughout the incubation period when checked for decrease in media pH of the media and thin layer chromatography. Thin layer chromatography of culture filtrates showed the presence of hydrocarbon like compound. Further analysis of the culture filtrates with gas liquid chromatography, a single peak near to the retention time of 7.6 was observed in all extracts of culture filtrates irrespective of phosphate source. UV-visible spectra of culture filtrates revealed the absorption maxima of 276 nm. Gas chromatographic-mass spectrometric analysis of culture filtrates showed most intense peak in the electron impact (EI) ionization was at m/z 149 and molecular ion peaks at m/z 207 and 167, inferring the presence of phthalic acid. Among the mechanisms in mineral phosphate solubilization, it was evident that these cyanobacteria used phthalic acid as possible mode of P solubilization.

Paraquat is most extensively used methyl viologen herbicide to control weeds in the rice-Azolla ecosystem. The effects of different paraquat (PQ) dosages on growth, lipid peroxidation, and activity of antioxidant enzymes of Azolla microphylla Kaul. were investigated. The results indicated that Azolla fronds survived only at the concentrations of 2–6 μM PQ. Frond fragmentation and browning occurred after 24 h at 8 μM PQ. At 24 h, the amount of proteins decreased by 48.7 % in Azolla fronds exposed to 10 μM PQ than that in control fronds. The supplementation of 10 μM PQ increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX) by 2,4-, 1,8-, 3,0-, and 2,2-fold, respectively, as compared with control. The content of PQ and activities of SOD, CAT, GPX, and APX were found to be positively correlated. Our study showed that PQ (2–6 μM) caused ROS overproduction in Azolla fronds, which were scavenged by induced activities of antioxidant enzymes.

The cyanobacteria are a diverse group of prokaryotic organisms that carry out oxygenic photosynthesis and are thought to be responsible for the oxygenation of our atmosphere. Like red algae and cryptomonads, cyanobacteria also contain phycobiliproteins (PBPs) which serve as major accessory pigments during photosynthesis. PBPs are large water-soluble supramolecular protein aggregates involved in light harvesting and can be divided broadly into three classes, viz., phycoerythrin (PE), phycocyanin (PC), and allophycocyanin (APC) based on their spectral properties. PBPs have been extracted and purified from Spirulina spp., Synechococcus sp., Oscillatoria sp., etc., and produced commercially from Spirulina platensis, Anabaena sp., and Galdieria sulphuraria. Since cyanobacteria exhibit wide variations in nutrient availability, light intensity, light quality (wavelength), temperature, water activity, etc., these variations also result in altered metabolic activity of these organisms as a result of differential expression of different genes. The expression of phycobiliprotein coding genes is also accordingly modulated to adapt to a particular condition. Many workers have reported changes in phycobilisome structure and expression of cpc genes in response to light quality, light quantity, and nutrients like nitrogen, sulfur, etc. The composition and function of phycobiliproteins in cyanobacteria have also been reported to change under stress conditions. In the present paper, we have reviewed the production, purification, and regulation of cyanobacterial phycobilins including their importance in the commercial sector, as they have several applications as natural dyes in food and cosmetic industry, immunological assays, health-promoting properties, and broad range of other pharmaceutical applications.

India has a total coastline of about 7000 km. The major vocation in the densely populated coastal region is agriculture. The majority of the coastal soils are waterlogged, saline to saline–sodic, low in carbon content and poor in productivity. The nitrogen dynamics of the coastal rice wetlands reclaimed by subsurface drainage was studied. Four areas with various drain spacings and two distinct stages of reclamation were considered. The land reclamation process through subsurface drainage of the areas with drain spacings of 15 and 25 m was started in 1986 and 1987, respectively. For the areas with 35 and 55 m drain spacings, the reclamation process was started in 1999. The data collection was carried out during 1999, 2000 and 2001. During the period of study, irrigated rice was cultivated in the areas with 15, 35 and 55 m drain spacings where the subsurface drainage system was operational. Drainage operation for the area with 25 m drain spacing was discontinued and the land left fallow. The study revealed that subsurface drainage improved the fertility status of the soil by promoting ammonium storage on the clay complex. Sustained operation of subsurface drainage system could maintain a favourable salt balance in the topsoil layer (0–30 cm) enhancing microbial activity and consequently nitrification. As a result, the nitrite concentration in soil water at field capacity was within the permissible limit of 0.9 mg/L in the rhizosphere. There was, however, a higher amount of nitrite accumulation in the area with impeded drainage. The three years’ data also established a gradual increase of nitrite accumulation in the 0–15 and 15–30 cm soil layers respectively. The nitrite concentration in these layers exceeded the permissible limit one year after discontinuation of the operation of the subsurface drainage system. Such a nitrite accumulation in the topsoil layer may give rise to nitrite toxicity to plants and become a threat to the sustainability of the coastal agro-ecosystem.

Application of high input technologies has resulted in significant increase in agricultural productivity. There is, however, a growing concern about the adverse effects of indiscriminate use of chemical fertilizers on soil productivity and environmental quality. Cyanobacteria offer an economically attractive and ecologically sound alternative to chemical fertilizers for realizing the ultimate goal of increased productivity, especially in rice cultivation. In a wetland rice ecosystem, nitrogen fixation by free living cyanobacteria also significantly supplements soil nitrogen.

α-Acetolactate synthase (α-ALS) of Enterobacter cloacae ATCC 27613 was purified to homogeneity by ammonium sulphate precipitation, Sephadex G-200 gel filtration and hydroxyapatite affinity chromatography. The molecular weight of the enzyme was found to be 60 kDa by SDS–polyacrylamide gel electrophoresis and ∼200 kDa by gel filtration through Sephadex G-200, showing that the enzyme is a homotrimer. The Km and Vmax of the enzyme were 20 mM and 200 μmol min−1 mg (protein)−1 respectively. The enzyme was optimally active at pH 6.0–8.0, 37 °C and showed concentration-dependent sensitivity to cofactors viz. FAD, NADP and NADPH and branched chain amino acids: leucine, isoleucine and valine. Substances like sodium formate, sodium acetate and sodium propionate, sugars and the selected intermediates of glycolytic pathway inhibited the enzyme. Glycerol, BSA and pyruvate-TPP stabilized the α-ALS. The enzyme showed the properties of both a catabolic as well as an anabolic α-ALS.

The biofertilizers, which are low cost inputs, renewable and pollution free have a crucial role in augmenting nutrient supply to crops by increasing their availability through exploitation of natural processes like biological nitrogen fixation, solubilization of insoluble P and decomposition of organic wastes etc. Blue Green Algae (BGA) find a highly favourable abode in the waterlogged conditions of rice fields and provide cheap nitrogen to plants besides increasing crop yield by making soil vital, fertile and productive. BGA biofertilizer in rice popularly known as “Algalization” helps in creating an environmentally safe agro ecosystem that ensures economic viability in paddy cultivation while saving energy intensive inputs. The agricultural importance of these organisms lies in their capacity to metabolize the molecular nitrogen, liberation of part of fixed nitrogen and growth promoting substances as extra metabolites, solubilising the insoluble phosphates, addition of organic matter and improving the physical and chemical nature of soil. Based on the natural ecology of these organisms, a rural oriented algal biofertilizer technology was developed which could be easily adopted by farmer for multiplication at their own level. The technology was introduced as a package of practices in a number of Indian states and showed positive results in terms of saving on chemical nitrogenous fertilizers and increasing crop yield. The technology has been substantially improved and the basic changes include; indoor production of algal biomass under semi-controlled conditions in a polyhouse for round the year production, a suitable and cheap growth medium for faster growth of the organisms and mixing with a suitable carrier material in desired quantities that supports higher microbial load with longer shelf life. This has also considerably reduced the quantity of inoculum per unit area. The product has been extensively tested in the field and established the advantage of using cyanobacterial inoculation in rice crop and its adoption as a management practice. It leads not only to saving on expensive inorganic chemical fertilizer but also sustains productivity by maintaining a continuous supply of crop nutrients. Considering the immense market potential, it is now desired that these products be exploited commercially.

The utilization of beneficial microbes as biofertilizers has become vital in agriculture sector for their prospective role in food safety and sustainable crop production. Biofertilizers keep the soil environment rich in all kinds of micro- and macro-nutrients via nitrogen fixation, phosphate and potassium solubilisation or mineralization, release of plant growth regulating substances, production of antibiotics and biodegradation of organic matter in the soil (Sinha et al, Int J Agric Health Saf 1:50–64, 2014). When biofertilizers are applied as seed or soil inoculants, they multiply and participate in nutrient cycling and benefit crop productivity (Singh et al, Agric Ecosyst Environ 140:339–353, 2011). Generally, 60 % to 90 % of the total applied fertilizer is lost and the remaining 10 % to 40 % is taken up by the plants. In this regard, microbial inoculants have supreme significance in integrated nutrient management systems to sustain agricultural productivity and healthy environment (Adesemoye and Kloepper Appl Microbiol Biotechnol 85:1–12, 2009).

Phycocyanin, a high value pigment was purified from diazotrophic cyanobacteria Anabaena variabilis CCC421 using a strategy involving ammonium sulfate precipitation, dialysis and anion exchange chromatography using DEAE-cellulose column. 36% phycocyanin with a purity of 2.75 was recovered finally after anion exchange chromatography. Purified phycocyanin was found to contain 2 subunits of 17 and 18 kDa which were identified as a-and (3 subunits by SDS-PAGE and MALDI-TOE HPLC method using a C5 column coupled with fluorescence or photodiode-based detection was also developed to separate and detect the A. variabilis CCC421 phycocyanin subunits. The fluorescence method was more sensitive than photodiode one. The purified phycocyanin from A. variabilis CCC421 as well as its subunits was characterized with respect to absorption and IR spectra. Spectral characterization of the subunits revealed that alpha and beta subunits contained one and two phycocyanobilin groups as chromophores, respectively.

In this study a simple protocol was developed for purifying phycocyanin (PC) from Spirulina platensis (CCC540) by using ammonium sulphate precipitation, followed by a single step chromatography by using DEAE-Cellulose-11 and acetate buffer. Precipitation with 65 % ammonium sulphate resulted in 80 % recovery of phycocyanin with purity of 1.5 (A620/A280). Thro1ugh chromatography an 80 % recovery of phycocyanin with a purity of 4.5 (A620/A280) was achieved. In SDS_PAGE analysis, the purified PC showed the presence of two subunit α (16 kD) and β (17 kD). Electronic supplementary material The online version of this article (doi:10.1007/s40502-014-0094-7) contains supplementary material, which is available to authorized users.