Search

Cyanobacteria have shown potential in promoting the health and growth of rice plants. A study was undertaken during kharif, 2018 to analyze the effect of two endophytic cyanobacterial strains isolated from the selected rice varieties on growth and yield of basmati (PB 1509) vis a vis non- basmati (Pusa 44) rice cultivars. The cyanobacterial strains namely C1 (a potential nitrogen fixer from rice variety IR 64) and C2 (an effective P solubilizer from rice variety Pusa 1612) belonging to Anabaena sp. were used. The field experiment consisted of control (T1) with recommended dose of fertilizer (RDF) along with four different combinations of fertilizer dose and cyanobacterial strains as T2 (RDF + C1); T3 (75% N in RDF + C1); T4 (RDF + C2) and T5 (RDF with 25% P as MRP and 75% P as SSP + C2), was conducted using split plot design with three replications. Treatments consisted of RDF alone (T1) without inoculum and inoculation with strain C1 with RDF (T2) and with 75% of nitrogen in RDF (T3). Strain C2 was used with RDF (T4) and with 25% P as MRP in RDF (T5). At 90 Days after Transplantation (DAT), the treatments T2 and T3 exhibited better response on per plant basis in terms of plant height (83.3 cm; 85.7 cm), dry weight of leaves (4.24 g; 4.79 g) and stem (13.2 g; 10.0 g) in basmati variety, while, treatment T4 showed better effect (75.3 cm) on plant height in non-basmati variety, which showed maximum dry weight of leaves (5.33 g) and stem (10.8 g) under treatment T5. However, number of tillers, panicle and grain weight per plant depicted variable results. Use of the cyanobacterial strains slightly enhanced N (0.5–1.8%) and P (1.3–2.3%) concentrations in plants at different stages of crop growth as well as at harvest stage.

The enormous capability of microalgae for biomass production and co-products has recently been widely researched from a range of research approaches. Microalgae biomass has been discovered as a suitable feedstock for biofuel generation in the third generation. Although they may easily be cultivated in the laboratory, commercial cultivation involves several important considerations, including design, expense, contamination risk, and hygiene. This paper reviews some conventional microalgal cultivation methods along with some harvesting techniques. A short note on the disadvantages of conventional microalgal biofilm cultivation and the need for advanced cultivation techniques are also listed. Further, it highlights some of the modern techniques used for the cultivation of biofilm-based microalgae. It also gives brief information on the various factors affecting the formation of microalgal biofilm. A detailed description of the application of microalgal biofilm concerning biofuel generation is also reviewed. Graphical abstract

In the present study, 24 green microalgae strains were isolated from selected aquatic sites of India. These were microscopically identified as Chlamydomonas sp., Scenedesmus sp., Chlorella sp., Dictyosphaerium sp. and Dunaliella sp. Nannochloropsis sp. (MCC 25), was used as a reference strain. Results showed that Dictyosphaerium sp. (MCC 10 and MCC 12) showed relatively higher nutritive content. The total soluble proteins in the reference strain was 21.4%, whereas it showed carbohydrate content of 17.2% and the lipids were 3.4% on a dry weight basis. Best performing strains were identified by biochemical characterization. Five genera were selected for molecular identification since they were the most representative based upon their area of isolation and their optimum content of total soluble proteins, carbohydrates and lipids. 18S rRNA sequencing authenticated their identification as Scenedesmus sp., Dictyosphaerium sp. and Chlorella sp. The sequences of these have been submitted in NCBI database with accession numbers as KT808247–KT808251. The correlation matrix showed positive correlation between carbohydrates and lipids, while negative correlation was seen between proteins and carbohydrates and between proteins and lipids. This study emphasizes the need for complete compositional analysis of the biomass for the possible applicability in the area of value addition.

Microalgae are considered potential feedstocks to generate biodiesel; however, the area requires further refinement and metabolic engineering to enhance productivity along with cost reduction. Our ...

Grain legumes are an important component of sustainable agri-food systems. They establish symbiotic association with rhizobia and arbuscular mycorrhizal fungi, thus reducing the use of chemical fertilizers. Several other free-living microbial communities (PGPR—plant growth promoting rhizobacteria) residing in the soil-root interface are also known to influence biogeochemical cycles and improve legume productivity. The growth and function of these microorganisms are affected by root exudate molecules secreted in the rhizosphere region. PGPRs produce the chemicals which stimulate growth and functions of leguminous crops at different growth stages. They promote plant growth by nitrogen fixation, solubilization as well as mineralization of phosphorus, and production of phytohormone(s). The co-inoculation of PGPRs along with rhizobia has shown to enhance nodulation and symbiotic interaction. The recent molecular tools are helpful to understand and predict the establishment and function of PGPRs and plant response. In this review, we provide an overview of various growth promoting mechanisms of PGPR inoculations in the production of leguminous crops.

Generation of biodiesel from microalgae has been extensively investigated; however, its quality is often not suitable for use as fuel. Our investigation involved the evaluation of biodiesel quality...

The study was conducted to analyse the influence of three nutrient formulations, namely BG-11 medium, BBM and TAP medium, on growth potential and lipid yield of two microalgal genera (Botryococcus sp. and Chlorella sp.) and to study the roles of N, P and other major nutrients. The study focussed on the general patterns of starch and lipid synthesis and storage and to further assess how photosynthetic carbon partitioning into starch and lipid is altered by conditions in growth media such as N and C presence as seen in BG11 medium which are known to induce neutral lipid production and the lack of it in BBM and TAP medium. BG-11 medium performed better as compared to BBM and TAP medium in terms of biomass productivity and lipid yield. The lipid yield was highest in Botryococcus sp. (63.03% dry wt.) and Chlorella sp. (50.27% dry wt.) at 30th day of incubation. Mean biomass productivity was highest for Botryococcus in BBM medium (6.14 mg/L/day) and for Chlorella in BG-11 medium (4.97 mg/L/day). Mean lipid productivity (50.78% and 39.36%) was highest in BG11 medium for both Botryococcus and Chlorella species, respectively. A sharp decline in sugar content was observed in the late stationary phase of growth from 30th day to 45th day. Fatty acid methyl ester (FAME) profile of the extracted lipids showed predominantly oleic acid, followed by palmitic acid and stearic acid in both the strains when grown in BG-11 medium. The other biodiesel quality parameters were in accordance with the international standards. A complex relationship was found between chemical composition and biodiesel properties. Proximity analysis indicated that the fuel properties of biodiesels are determined by a number of parameters and by the combination of different chemical compositions. The results provide an insight into organic carbon partitioning into lipid compounds and how the organism’s lipid metabolism changes due to N-deplete culturing in TAP medium and inorganic carbon source availability as seen in BG-11 and BBM medium.

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.

Effects of the environmental variables such as light intensity (Vmol photons m⁻² S⁻¹), temperature (*C) and CO₂ concentration (ppm) on chlorophyll, total soluble proteins and lipids were studied in selected microalgal strains from Chlorophyceae (Chlamydomonas sp., Scenedesmus sp., Chlorella sp., Kirchneriella sp.) and cyanobacteria (Nostoc sp.1, Anabaena sp., Nostoc sp. 2, Cylindrospermum sp.). Cultures were grown under controlled conditions at the National Phytotron Facility, Indian Agricultural Research Institute (IARI), New Delhi. Our results showed that chlorophyll concentration enhanced with increased C0₂. Chlorella exhibited the highest chlorophyll at 850 ppm CO₂ and 28*C; for Chlamydomonas it was at 78 μmol photons m⁻² S⁻¹ light intensity. In Cylindrospernum, total soluble proteins decreased with enhanced C0₂, and were highest at 18*C. In Anabaena, a light intensity of 65 μmol photons m⁻² S⁻¹ was best for maximum total soluble proteins. In Chlorella, CO₂ @ 850 ppm was most suited for maximum lipid accumulation. In Kirchneriella, increase in temperature, from 18*C up to 370C, increased total lipids; the highest was at 28'C. In Chlamydomonas, the light intensity of 78 μmol photons m⁻² S⁻¹ was optimum for lipid accumulation and the maximum total lipids was 30.8 (% dry wt.).

Identification of cost-effective cell disruption methods to facilitate lipid extraction from microalgae represents a crucial step in identifying promising biofuel-producing species. Various cell disruption methods including autoclaving, microwave, osmotic shock, and pasteurization were tested in the microalgae Chlorococcum sp. MCC30, Botryococcus sp. MCC31, Botryococcus sp. MCC32, and Chlorella sorokiniana MIC-G5. Lipid content (on dry weight basis) from the four cultures on day 7 ranged from 11.15 to 48.33%, and on day 14 from 11.42 to 44.26%. Among the methods tested, enhanced lipid extraction was achieved through osmotic shock (15% NaCl) for Botryococcus sp. MCC32, microwave (6 min) for Botryococcus sp. MCC31, osmotic shock (5% NaCl) for Chlorella sorokiniana MIC-G5 and microwave (2 min) for Chlorococcum sp. MCC30. The highest palmitate (16:0) contents (25.64% and 34.20%) were recorded with osmotic shock (15% NaCl) treatment for Botryococcus sp. MCC32 and microwave (6 min) for Botryococcus sp. MCC31, respectively. Two strains, along with their respective cell disruption methods, were identified as promising oil blends or nutraceuticals due to their high unsaturated fatty acid (UFA) content: Botryococcus sp. MCC31 (37.6% oleic acid content; 39.37% UFA) after autoclaving and Botryococcus sp. MCC32 after osmotic shock of 15% NaCl treatment (19.95% oleic acid content; 38.17% UFA).

Microalgae are reported as the efficient source of renewable biodiesel which should be able to meet the global demand of transport fuels. Present study is focused on assessment of wastewater grown indigenous microalga Chlorella sp. for fuel quality parameters. This was successfully grown in secondary treated waste water diluted with tap water (25% dilution) in glass house. The microalga showed a dry weight of 0.849 g L−1 with lipid content of 27.1% on dry weight basis on 21st day of incubation. After transesterification, the yield of fatty acid methyl ester was 80.64% with major fatty acids as palmitic, linoleic, oleic and linolenic. The physical parameters predicted from empirical equations in the biodiesel showed cetane number as 56.5, iodine value of 75.5 g I2 100 g−1, high heating value 40.1 MJ kg−1, flash point 135 °C, kinematic viscosity 4.05 mm2 s−1 with density of 0.86 g cm3 and cold filter plugging point as 0.7 °C. Fourier transform infra-red (FTIR), 1H, 13C NMR spectrum confirmed the chemical nature of biodiesel. The results indicated that the quality of biodiesel was almost as per the criterion of ASTM standards; hence, wastewater grown Chlorella sp. can be used as a promising strain for biodiesel production.

Cyanobacteria belong to a diverse group of photosynthetic prokaryotes. They are increasingly being used as biofertilizer in agriculture due to their role as diazotrophs, ameliorant for soil physical and chemical properties, establishing proficiency in diverse soil ecologies, and their ability to compete with native flora and fauna. These are producers of a large number of biologically active/biocidal substances. However, most researches concerning them and their derived products focus on pharmaceutical applications and their use in agriculture is often regarded as a secondary goal. Existing literature suggests that cyanobacteria may play a potential role in crop protection. Thus, this is the first review of its kind that focuses on the potential application of cyanobacteria for crop protection. Commercial development of cyanobacterial compounds for non-biomedical applications includes herbicides, algicides, nematocides and insecticides. Bioactive compounds like, hapalindoles from Fischerella, calothrixins from Calothrix, cyanobacterins LU-1 and LU-2 from Nostoc and γ–lactone from Scytonema are proposed to possess allelopathic effect. Cyanobacteria show significant biocidal activity against important agricultural insect-pests. The biomass extract of Nostoc can kill Helicoverpa armigera larvae at a dose of 2.20 mg cm−2. The antimicrobial substances produced include nostocyclyne A, nosto fungicidin, nostocin A, Ambigol A and B, hapalindoles, tjipanazoles and scytophycins and exhibit fungicidal activity against important plant pathogens. These biocontrol agents provide multiple benefits and act as useful pointers for improving cultivation practices and establishment of plants in diverse inhospitable/barren habitats. They depict a promising multifaceted bioinoculants in organic farming practices popular in present day agriculture.

Cost-efficient harvesting of microalgae is a major challenge due to their small size and often low concentration in the culture medium. The flocculation efficacy of different inorganic and organic amendments was evaluated on various microalgae genera—one strain each belonging to Chlamydomonas, Chlorococcum, two of Botryococcus, and of Chlorella. An improvised medium comprising of commercial grade urea, single super phosphate, and muriate of potash was used to grow the microalgae for flocculation experiments. High pH induced increased flocculation efficiency (72–76 %) in selected microalgal strains. Ferric chloride was found to be the most efficient for most of the microalgal strains, while maize starch and rice starch proved superior for Chlorella sp. MCC6 and Botryococcus sp. MCC32. Although the highest flocculation efficiency was obtained with inorganic flocculant, i.e., ferric chloride (87.3 %) with Botryococcus MCC31, this was comparable with rice starch (86.8 %) for Botryococcus MCC32. This study showed that widely available cheaper biopolymers such as rice starch, maize, and potato starch can be promising flocculants due to their better harvesting efficiency (>80 %) and low price, thereby contributing to economical production of biodiesel from algae.

Our study focused towards screening the modes of nutrition of Chlorella sorokiniana under standard laboratory conditions and its upscaling in a photobioreactor for enhanced lipid productivity. Time course studies using glucose under mixotrophic and heterotrophic conditions vis a vis autotrophy revealed highest values of growth, lipid productivity (29.33% DCW) and lipid content (755. 00 mg/L) under mixotrophic conditions on the 14th day of growth. Upscaling in a photobioreactor with selected substrates (Glucose and tryptophan), along with sodium thiosulphate as a reducing agent was undertaken. Lipid productivity of 34.16% and 36.49% was recorded after 4th and 8th day, respectively, in both substrates, vis a vis 11% with glucose alone. FAME analyses revealed a 2% enhancement in total saturated fatty acids (SFA) in tryptophan supplemented culture, which also exhibited an almost ideal fatty acid ratio for use as biodiesel (2.6:4:1 of 16:1.18:1 and 14:1). Interestingly, glucose+sodium thiosulphate grown culture exhibited an almost 2 folds enhancement in PUFA content (especially 18:1 and 18:2), illustrating its promise for use as an edible oil blend. Our study revealed the step-wise scale up and promise of substrate amendment and mixotrophy as promising tools for valorization of microalgal lipids.

A biphasic nutritional strategy was employed for enhancing lipid accumulation in the three selected microalgae Chlorella sp. MIC-G4, Chlorella sp. MIC-G6 and Scenedesmus sp. MIC-G8, involving supplementation with different nitrogen sources (NaNO 3 , KNO 3 , urea and (NH 4 ) 2 CO 3 ), followed by their limitation. NaNO 3 was found to be the best for enhancing lipid accumulation. Palmitic, linoleic and alpha linolenic acids were the most abundant fatty acids. MIC-G6 recorded the highest content of α- linolenic acid (43.7% of total fatty acid) after 32 d growth in nitrogen rich medium and 36.0%, after 24 d growth in nitrogen rich medium followed by 8 d in nitrogen limited medium. An enhancement of 40–50% in lipids on dry weight basis was recorded in Chlorella sp. MIC-G4 and Scenedesmus sp. MIC-G8, in the treatment involving 24 d growth in nitrogen rich medium, and 8 d in nitrogen limited medium. An abundance of 92–97% (% of total fatty acids) of C16–C18 fatty acids was recorded. Our study illustrates the promise of MIC-G4 and MIC-G8 as a source of lipids, triggered by the biphasic mode of cultivation, and the need to undertake in-depth gene expression profiling to enhance further the lipid accumulation.

Ten cyanobacterial isolates from the hyper-saline environment of Rann of Kutch were characterized for growth related physiological variables. A wide variability was observed in chlorophyll, protein and sugar content among the isolates. Similarly carotenoids, phycoerythrin and allophycocyanin contents also varied among the isolates. Differential activity of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, catalase and levels of proline were related to the ability of the strains to survive at higher salinity levels.

The nematicidal activity of a terrestrial cyanobacterium, Synechococcus nidulans, was investigated. Extracts of S. nidulans cultures collected at weekly intervals for 5 weeks were sonicated and tested against second-stage juveniles (J2) of Meloidogyne incognita. Extracts of 2-week-old cultures caused the maximum immobility (94.2%) and mortality (29.3%) of J2, compared with controls (medium and water). This extract was tested in vitro against infective stages and hatch of M. graminicola, Heterodera cajani, H. avenae and Rotylenchulus reniformis. Extracts of sonicated S. nidulans caused a mean immobility in the range of 91.3-98.4% in infective stages of the nematodes, with no significant difference with an increase in exposure time from 24 to 72 h. The greatest mean percentage mortality was observed in M. graminicola (31.5%) followed by M. incognita (29.3%), H. avenae (20.9%), and R. reniformis and H. cajani (both 17.4%) with a significant increase with the period of exposure from 24 to 72 h. No significant differences in mortality were observed between M. graminicola and M. incognita and between H. avenae and H. cajani. The percentage hatch inhibition over control (water) was greatest in M. incognita (94.2%), followed by H. avenae (91.6%), H. cajani (72.3%) and M. graminicola (70.6%), and least in R. reniformis (58.6%).

Our study reports the collection, biodiversity analyses, isolation and identification of microalgae from different habitats of India. Cyanophyceae and Chlorophyceae were the most dominant algal groups recorded, with the highest number being recorded for non-heterocystous cyanobacteria (48), followed by 44 unicellular forms. Sagar Island, Sunderbans recorded the greatest number of algae, and unicellular/colonial green algae were present in all the samples. Shannon's Diversity Index was highest in Koikhali, Sunderbans, followed by Rushikulya River, Odisha. Selective enrichment, purification through serial dilution followed by plating and regular observations led to the isolation of sixteen strains. Identification was done by using microscopic observations, supported with standard monographs and classified as belonging to seven genera (Chlorella, Chlorococcum, Kirchneria, Scenedesmus, Chlamydomonas, Tetracystis and Ulothrix). 18S rDNA sequencing was undertaken for four strains. The set of sixteen strains were screened under standard cultural conditions for their growth kinetics and Chlorella sorokiniana MIC-G5, followed by Chlorella sp. MIC-G4 exhibited the highest growth rates. The strain Chlorococcum sp. MIC-G2 recorded highest chlorophyll, while MIC-G3 ranked highest for carbohydrates. The study aided in identifying the dominant microalgae in the diverse habitats and characterizing their growth rate and carbohydrate content, providing a valuable germplasm for further utilization in agriculture and industry.

Molecular polymorphisms in a selected set of Spirulina and related genera using random primers based on repetitive sequences along with biochemical parameters, led to the unambiguous differentiation of the strains and understanding of their phylogenetic relationships. A combination of 10 sets of dual primers generated 100% distinct polymorphic bands ranging from 150 to 5,000 bp. Total number of fragments ranged from 68 to 159 whereas polymorphic bands ranged from 13 to 32 for different Random Amplified Polymorphic DNA (RAPD) reactions. Spirulina platensis strains, Sp-2 and Sp-3, possessed quite comparable chlorophyll and protein content besides having maximum similarity coefficient (0.88) between them on the basis of RAPD reactions, thus proved to be closely related. Sp-8 (Spirulina from Loktak Lake) having the highest protein content and protein: chlorophyll ratio, showed close similarity with the mutant of Spirulina platensis (Sp-7) on the basis of RAPD analysis. Duncan’s Multiple Range Test (DMRT) ranking for the biochemical parameters were quite closer for the strains of Spirulina and Arthrospira. This is also supported by the cluster analysis based on RAPD data, as the strains of Spirulina and Arthrospira are placed together in the same subcluster in the dendrogram. The comparative closeness among the strains of Lyngbya, Oscillatoria and Phormidium is reflected by the low content of protein and protein: chlorophyll ratio, which is also supported by the dendrogram based upon RAPD; thus, exhibiting the usefulness of multiplex RAPD along with biochemical parameters for the phylogenetic analysis of Spirulina and related genera.

Ten strains of Azotobacter chroococcum were studied for their ability to invade the endorhizosphere of wheat. Strain W-5 exhibited ability to invade endorhizosphere as shown in the microscopic observations. This strain was compared with the strain OA-3 which did not invade the endorhizosphere zone. Strain W-5 showed higher production of cellulase and pectinase than OA-3. Both the strains induced defense enzymes in the host plant. However, induction of peroxidase and phenylalanine ammonia lyase activities (PAL) was higher in OA-3 than W-5. Quantitative differences in flavonoid like compounds obtained from root extracts and root exudates of plants inoculated with these strains were observed.

Azolla microphylla plants exposed directly to NaCl (13 dsm(-1)) did not survive the salinity treatment beyond a period of one day, whereas plants exposed directly to 4 and 9 dsm(-1) NaCl were able to grow and produce biomass. However, plants pre-exposed to NaCl (2 dsm(-1)) for 7 days on subsequent exposure to 13 dsm(-1) NaCl were able to grow and produce biomass although at a slow rate and are hereinafter designated as pre-exposed plants. The pre-exposed and directly exposed plants distinctly differed in their response to salt in terms of lipid peroxidation, proline accumulation, activity of antioxidant enzymes, such as SOD, APX, and CAT, and Na(+)/K(+) ratio. Efficient modulation of antioxidant enzymes coupled with regulation of ion transport play an important role in the induction of salt tolerance. Results show that it is possible to induce salt adaptation in A. microphylla by pre-exposing them to low concentrations of NaCl.

Analyses of molecular polymorphisms in a selected set of Calothrix strains, using primers based on repetitive sequences in the genome, led to the unambiguous differentiation of the strains as well as understanding of their genetic relationships. Seventeen 10 mer random primers were used singly and twelve dual primer combinations were used to examine the phylogenetic relatedness amongst the strains using RAPD- PCR. A total of nine hundred distinct polymorphic DNA fragments (bands), ranging from 0.18 kb to 5.00 kb were produced in PCR reaction with single oligos. A combination of twelve sets of primers generated nine hundred three distinct polymorphic DNA fragments (bands), ranging from 0.13 kb to 6.22 kb, which revealed a wide range of variability amongst the strains. The combined analysis of single and multiplex primer combination showed a maximum correlation coefficient of 0.821 amongst two strains (Ca28 and Ca29) with chlorophyll contents of 4.08 μg/ml and 3.57 μg/ml. These two isolates belonged to same geographical location. The study undertaken has revealed extensive evidence for the applicability of RAPD in cyanobacterial taxonomy, and furthermore, clearly demonstrated the superior discriminative power of RAPD towards the differentiation of geographically unrelated Calothrix strains.

The impact of nitrogen-fixing blue-green algal (BGA) strains, namely Anabaena variabilis, Aulosira fertilissima, Nostoc muscorum and Tolypothrix tenuis , was studied at different levels of nitrogen fertilizer on specific soil parameters such as microbial populations, pH, EC, redox potential, chlorophyll, dehydrogenase and nitrogenase activity under a rice crop. The inoculation of the soil with BGA strains resulted in higher microbial populations (BGA, bacteria, fungi and actinomycetes) and had a significant influence on redox potential. A significant increase in soil chlorophyll, dehydrogenase and nitrogenase activity was observed during crop growth due to BGA application.

Nitrogen fixing cyanobacteria or blue green algae are ecologically significant inputs in rice cultivation in the tropics. Field experiments were conducted to compare the efficiency of two newly developed carrier based blue green algal (BGA) biofertilizers (wheat straw and multani mitti), with the traditional soil based BGA biofertilizer, on the grain yield of rice for a period of three years. Treatments included five levels of nitrogenous fertilizer urea and their interaction with the three types of BGA biofertilizers, on the grain yield of rice variety ‘PNR 381’. Highest grain yields were obtained with the application of multani mitti based biofertilizer along with 90 kg N/ha, although maximum percent increase in yield over control (37.97%), when applied along with 60 kg N/ha. The straw based and soil based biofertilizer treatments showed highest yields when supplemented with 90 and 120 kg N/ha, respectively. This investigation clearly emphasizes the need for supplementing chemical fertilizers w...

Microalgal Remediation of Sewage Effluent

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).

Soils contain enormous numbers of diverse living organisms assembled in complex and varied communities. Microscopic examination of a soil sample reveals the presence of billions of organisms like nematodes, protozoa, fungi, algae, actinomycetes, bacteria and cyanobacteria. These diverse organisms interact in the ecosystem, forming a complex web of biological activity. Environmental factors, such as temperature, moisture and acidity, as well as human activities such as agricultural and forestry management practices, affect soil biological communities and their functions. Soil biology is an interesting area of soil research and has yielded considerable information that is used in soil fertility management.

Chemical (N' methyl-N'-nitro-N-nitrosoguanidine) mutagenesis and penicillin selection were utilised to isolate a phenotypically altered mutant of cyanobacterium Synechocystis sp. This mutant (ntm60A) exhibited enhanced protein content and nitrogen fixing potential but lower amount of chlorophyll and nitrate reductase activity. A remarkable and significant increase was observed in the total phycobiliprotein content of the mutant, especially in relation to the amount of phycoerythrin. This strain can be exploited as a rich source of natural coloring agent such as phycobilins in the bioindustry.

Blue Green Algae: A Potential Biofertilizer for Sustainable Rice Cultivation

Diversity Analysis of Cyanobacteria from Aquatic Bodies

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.

The effect of environmental variables like light intensity (µEm -2 s -1 ), temperature (° C) and CO2 concentration (ppm) was studied on chlorophyll and lipid content in selected microalgal strains. The strains used were the members of green algae (Chlorella sp., Chlamydomonas sp., Kirchneriella sp., Scenedesmus sp.) and blue green algae (Nostoc sp.1, Nostoc sp.2, Anabaena sp. and Cylindrospermum sp.). These were grown in culture room and in special growth chambers under National Phytotron Facility of the Institute. The temperature of 37° C was optimum for most of the microalgal strains while 850ppm CO2 concentration was observed to be good in terms of total lipids. Light intensity of 65µEm-2s-1 and 72µEm-2s-1 was favourable for enhanced lipid

Spirulina has attracted special attention due to its importance as human foodstuff and natural colours with specific functional properties. These functional properties have been attributed to phycobilins, carotenoids, phenolics and unsaturated fatty acids. Present study was conducted under controlled phytotron conditions to identify the efficient strains of Spirulina in terms of pigment synthesis and to optimize their enhanced production. Methodology for enhanced production was standardized by varying specific environmental parameters (light intensity, temperature, carbon dioxide concentration, pH and NaCl level). Different strains of Spirulina depicted variability and environmental parameters showed distinct influence on pigments. Growth and pigment production was recorded to be most efficient under optimized conditions of light intensity (70 μmol m−2 s−1), temperature (30 °C), CO2 concentration (550 ppm and 750 ppm), pH (10.5) and NaCl level (2 g L−1).

Microalgae are autotrophic microorganisms having extremely high photosynthetic efficiency and are valued as rich source of lipids, hydrocarbons, and other complex oils for biodiesel besides being an invaluable source of bioethanol, biomethane, and biohydrogen. Biodiesel produced from oilseed crops such as jatropha and soy have lower yields per unit land area and threaten food security. Indeed, microalgae have higher oil yields amounting to about 40 times more oil per unit area of land in comparison to terrestrial oilseed crops such as soy and canola. Further, microalgae production does not require arable land for cultivation. Biofuel is regarded as a proven clean energy source and several entrepreneurs are attempting to commercialize this renewable source. Technology for producing and using biofuel has been known for several years and is frequently modified and upgraded. In view of this, a review is presented on microalgae as second generation biofuel. Microalgal farming for biomass production is the biggest challenge and opportunity for the biofuel industry. These are considered to be more efficient in converting solar energy into chemical energy and are amongst the most efficient photosynthetic plants on earth. Microalgae have simple cellular structure, a lipid-rich composition, and a rapid rate of reproduction. Many microalgal strains can be grown in saltwater and other harsh conditions. Some autotrophic microalgae can also be converted to heterotrophic ones to accumulate high quality oils using organic carbon. However, there are several technical challenges that need to be addressed to make microalgal biofuel profitable. The efficiency of microalgal biomass production is highly influenced by environmental conditions, e.g., light of proper intensity and wavelength, temperature, CO2 concentration, nutrient composition, salinities and mixing conditions, and by the choice of cultivation systems: open versus closed pond systems, photobioreactors. Currently, microalgae for commercial purpose are grown mostly in open circular/elongated “raceway” ponds which generally have low yields and high production costs. However, a hybrid system combining closed photobioreactor and open pond is a better option. The biggest hurdle in commercialization of microalgal biofuel is the high cost and energy requirement for the microalgal biomass production, particularly agitation, harvesting, and drying of biomass. In order to conserve energy and reduce costs, algae are often harvested in a two-step process involving flocculation followed by centrifugation, filtration, or micro-straining to get a solid concentration. However, the major bottlenecks in algal biodiesel production within the cell can be identified and handled by adopting a system approach involving transcriptomics, proteomics, and metabolomics. Research and developments in the field of new materials and advanced designs for cultivation in closed bioreactors, use of waste water for biomass production, screening of efficient strains, high-value coproduct strategy, and cutting-edge metabolic engineering are thought to provide the biggest opportunities to substantially improve the cost effectiveness of such production systems.

Ten strains of Azotobacter chroococcum were studied for their ability to invade the endorhizosphere of wheat. Strain W-5 exhibited ability to invade endorhizosphere as shown in the microscopic observations. This strain was compared with the strain OA-3 which did not invade the endorhizosphere zone. Strain W-5 showed higher production of cellulase and pectinase than OA-3. Both the strains induced defense enzymes in the host plant. However, induction of peroxidase and phenylalanine ammonia lyase activities (PAL) was higher in OA-3 than W-5. Quantitative differences in flavonoid like compounds obtained from root extracts and root exudates of plants inoculated with these strains were observed.

Cyanobacterial strains belonging to Nosctoc, Anabaena and Cylindrospermum were isolated from rice grown acidic soils of Kerala, Nagaland and Tea garden of West Bengal. These were grown, maintained and analysed for growth potential and selected biochemical attributes. The experimental results of this study showed that some cyanobacterial strains were acid tolerant achieving higher growth rate at pH 4 and 4.5 rather than 5.5. The pigments and cellular constituents of these strains showed variability under three acidic pH indicating their specificity to regulate adaptability to acidic soils.