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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.

In house cultivated Spirulina powder was incorporated at 2 to 15% concentrations to enrich pasta prepared from semolina. Spirulina incorporation led to development of green color pasta with nutritional and functional fortification resulting in increase in its protein, total phenols, flavonoids, iron and calcium content by up to 77.47%, 76.62%, 162.88%, 296.99% and 57.27%, respectively, without causing detrimental changes to the textural and sensory attributes. FAME analysis revealed 2 to 2.5 times enhanced levels of γ-linolenic acid and docosahexaenoic acid in enriched pasta. Significant improvement in phenolics, flavonoids and antioxidant activity were also observed in comparison to control pasta. Analysis of theoretical and realized composition confirmed retention of nutrients post cooking revealing no significant loss in proteins and other nutrients. Principal components analysis demonstrated significant contribution of Spirulina to nutritional and functional attributes especially at higher concentrations. Pasta enriched with 12.5% Spirulina was rated as “liked very much” and the purchase intention was also high. Spirulina enrichment at concentrations above 10% (12.5%) with appreciable increase in nutritional and functional attributes without affecting textural or cooking quality and acceptable sensory evaluation can be a preferred alternative to augment health and prevent sickness. Since green color symbolizes freshness, hope, renewal and physical health, the consumption of Spirulina incorporated green pasta may be a potential option to enhance the livelihood and nutritional security of rural poor and a good alternative for hidden hunger alleviation programs for mass nutrition especially for infants and children in an effective manner.

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.

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.

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 nitrogen fixing cyanobacterial strains namely Anabaena variabilis (Nostocales, Nostocaceae) and Westiellopsis prolifica (Nostocales, Hapalosiphonaceae) were evaluated for their nitrogen fixation and growth potential in response to different concentrations (10, 20 and 30 mg P) of the alternate insoluble P-sources Mussorie Rock Phosphate and Tricalcium Phosphate. Distinct and significant intergeneric differences were observed with respect to nitrogen fixation measured as Acetylene Reduction Activity (ARA) and growth potential as soluble proteins, total carbohydrate content, dry weight and total chlorophyll content in response to different concentrations of Mussorie Rock Phosphate and Tricalcium Phosphate. Both the strains showed higher soluble protein content at 20 mg P (Mussorie Rock Phosphate) that increased with time of incubation in A. variabilis. Both cyanobacteria recorded maximum Acetylene Reduction Activity at 20 mg P (Tricalcium Phosphate) followed by activity in presence of soluble phosphate (K2HPO4). The mean activity at all concentrations of insoluble phosphate (Mussorie Rock Phosphate and Tricalcium Phosphate) was more than in the presence of soluble phosphate.

Three Spirulina strains which were able to withstand salt stress were evaluated for lipid accumulation and fatty acid profile under different salinity levels and incubation period. Presence of salt stress increased the lipid accumulation in selected Spirulina strains upto 25.53%. The fatty acid profile varied differently as palmitic, linolenic, oleic, linoleic and docosahexaenoic acids (in order of abundance) were most prevalent. Fatty acid ratios were found to be different under different salt stress conditions and incubation times in which PUFA and γ -linolenic acid was accumulated in higher quantities at increased salt stress in all Spirulina strains.

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).