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Blue and red light significantly aid in the recovery of damaged cells of the cyanobacterium Synechocystis sp. PCC 6803 exposed to ultraviolet radiation
(Springer Nature, 2025) Prashant R. Singh; Ashish P. Singh; Amit Gupta; Shailendra P. Singh; Rajeshwar Prasad Sinha
Cyanobacteria are the most promising models for CO2 sequestration, production of chemicals, and renewal energy. Being photosynthetic organisms, they are continuously exposed to different intensities and wavelengths of light, including ultraviolet radiation (UVR). In the present investigation, we studied photosynthetically active radiation (PAR + UV−A + UV−B (PAB) effects on the cyanobacterium Synechocystis sp. PCC 6803 and its recovery under different wavelengths of light, such as PAR, blue light (BL), green light (GL), and red light (RL). The Chl a and total carotenoid content recovered maximally under BL and RL, whereas phycocyanin (PC) under BL. Maximum recovery in the photosynthetic performance was observed under GL and RL, whereas the least recovery was under BL. After 48 h of PAB irradiation, minimum ROS was found under dark conditions. The maximum number of non-viable cells was found in 24 h PAB, and in the recovery phase, it was found in BL and RL. Thus, it was evident that PAB negatively affects the growth, development, and overall fitness of Synechocystis sp. PCC 6803. The different wavelengths of light play a significant role in the recovery of the cyanobacterium Synechocystis sp. PCC 6803. © The Author(s), under exclusive licence to the European Photochemistry Association, European Society for Photobiology 2025.
Pollution affecting cyanobacteria in aquatic habitats
(Springer International Publishing, 2021) Abha Pandey; Sonal Mishra; Neha Kumari; Vidya Singh; Rajeshwar P. Sinha
Aquatic ecosystems comprise the largest portion (~72%) of the biosphere and play a crucial role in stabilizing the global climate as well as providing a large array of services for a fast-growing human population. Nowadays, there is a growing amount of data that prove that many anthropogenic pollutants from agricultural, urban and industrial wastes are dumped in the aquatic ecosystems and accumulate in many environments, including the habitats of marine and freshwater cyanobacteria. Cyanobacteria, as a natural part of phytoplankton assemblages, are known for their role as dominant primary producers and base of aquatic food webs. These microorganisms are continuously exposed to various concentrations of the pollutants that are present in their habitats and affect cyanobacterial communities at different levels such as abundance, growth strategies, succession patterns and dominance. Even if no direct changes in cyanobacterial communities are visible, the pollutants may accumulate in cyanobacteria and be passed onto higher trophic levels in a cascading manner, resulting in biomagnifications of certain pollutants. The most common pollutants in aquatic ecosystems are heavy metals, herbicides, pesticides, nutrients, pharmaceuticals, polycyclic aromatic hydrocarbons and microplastics. It is important to determine their concentrations in cyanobacterial cells and in their environment to know the possibility of contaminants that might be transferred to higher trophic levels. However, some strains of cyanobacteria are capable of metabolizing these pollutants that makes them less toxic or sometimes they even remove pollutants from the environment. This chapter highlights the toxic effects of different types of pollution (both point sources and non-point sources) on cyanobacterial communities in aquatic habitats. The anthropocentric concept of "pollution" and the links between pollution, eutrophication and harmful algal blooms (HABs) are also analyzed. An understanding of the synergistic interactions between these aspects and climate change effects will be useful to devise suitable remediation strategies for future use. © Springer Nature Switzerland AG 2021. All rights reserved.
Protein Engineering in Cyanobacterial Biotechnology: Tools and Recent Updates
(Bentham Science Publishers, 2024) Swati Tyagi; Srabani Kar; Amit Srivastava; Pratyoosh Shukla
Cyanobacteria have emerged as a microbial cell factory to produce a variety of bioprod-ucts, including peptides and proteins. Cyanobacteria stand out among other organisms due to their photoautotrophic metabolism and ability to produce a wide range of metabolites. As photoau-totrophic hosts can produce industrial compounds and proteins by using minimal resources such as sunlight, atmospheric carbon dioxide, and fewer nutrients, cyanobacteria are cost-effective industrial hosts. Therefore, the use of protein engineering tools for rational protein design, and the de-sired modification of enzyme activity has become a desirable undertaking in cyanobacterial biolo-gy. Protein engineering can improve their biological functions as well as the stability of their intracellular proteins. This review aims to highlight the success of protein engineering in the direction of cyanobacterial biotechnology and outlines the emerging technologies, current challenges, and prospects of protein engineering in cyanobacterial biotechnology. © 2024 Bentham Science Publishers.
The synechocystis sp. PCC 6803 genome encodes up to four 2-phosphoglycolate phosphatases
(Frontiers Media S.A., 2018) Snigdha Rai; Stefan Lucius; Ramona Kern; Hermann Bauwe; Aaron Kaplan; Joachim Kopka; Martin Hagemann
Photorespiratory phosphoglycolate (2PG) metabolism is essential for cyanobacteria, algae, and plants. The first enzyme of the pathway, 2PG phosphatase (PGPase), is known from plants and algae but was scarcely investigated in cyanobacteria. In silico analysis revealed four candidate genes (slr0458, slr0586, sll1349, and slr1762) in the genome of the model cyanobacterium Synechocystis sp. PCC 6803 that all belong to the 2-haloacid dehalogenase (HAD) superfamily and could possibly encode PGPase proteins. However, in contrast to known algal and plant PGPases, the putative cyanobacterial PGPases belong to another HAD subfamily implying that PGPases in eukaryotic phototrophs did not originate from cyanobacterial PGPases. To verify their function, these four genes were inactivated both individually and in combination. A mild high-CO2-requiring (HCR) growth phenotype typical for photorespiratory mutants was observed only in Δsll1349. Combinatorial inactivation enhanced the HCR phenotype in specific double and triple mutants. Heterologous expression of the putative cyanobacterial PGPases in E. coli led to higher PGPase activities in crude cell extracts, but only the purified Slr0458 protein showed PGPase activity. Hence, we propose that a consortium of up to four photorespiratory PGPases may initiate photorespiratory 2PG metabolism in Synechocystis. We suggest that redundancy of this essential enzyme activity could be related to the highly adaptive lifestyle of cyanobacteria such as Synechocystis sp. PCC 6803, which allows them to grow under very diverse conditions. © 2018 Rai, Lucius, Kern, Bauwe, Kaplan, Kopka and Hagemann.
Malleability of cyanobacteria for attaining sustainable development goals (SDG 7)
(Nova Science Publishers, Inc., 2022) Rupanshee Srivastava; Nidhi Singh; Tripti Kanda; Sadhana Yadav; Rajesh Prajapati; Shivam Yadav; Neelam Atri
Due to the finite nature of fossil fuels, it is essential to discover affordable and clean renewable energy resources and thereby attain UN-Sustainable Development Goals. This book chapter discusses cyanobacteria, a third-generation renewable energy resource that does not conflict with our food supply. Cyanobacteria are a complex collection of microbes that, as members of marine and freshwater phytoplankton, contribute significantly to atmospheric carbon fixation through photosynthesis. Pyrolysis can transform the biomass of contemporary cyanobacteria into bio-oil. As membrane components, storage products, metabolites, and energy sources, microalgae comprise about 2-40% lipids and fatty acids. Cyanobacteria grow quickly, do not compete for agricultural areas and resources, and efficiently convert large volumes of carbon dioxide into biomass, allowing them to participate in both carbon fixation and the creation of organic chemicals. Eukaryotic algae and other photosynthetic organisms are more difficult to genetically alter than cyanobacterial species. As a result, the photosynthesis of cyanobacteria might be guided to produce carbohydrates, fatty acids, or alcohols as sustainable biofuels. This chapter will discuss recent advances in the creation and production of cyanofuels, which are biofuels made from cyanobacterial biomass. The importance of cyanobacteria's primary metabolic pathways is underlined, and the prospect of influencing these pathways to boost the generation of various types of energy is the focus of this chapter. © 2022 Nova Science Publishers, Inc..
Cyanobacteria, pesticides and rice interaction
(Kluwer Academic Publishers, 2015) N.P. Das; Ajay Kumar; P.K. Singh
Cyanobacteria (blue-green algae) are widely distributed in tropical wet land rice fields where they play important role in building soil fertility. Due to their ability to photosynthesize and fixing atmospheric nitrogen, these are used as inoculants in rice fields to obtain additional benefits. The fertilizers and pesticides are being extensively used and therefore, it is necessary to find out effects of agrochemicals particularly pesticides on non target organisms like cyanobacteria. In the present investigation interaction of pesticides and cyanobacteria has been studied at different stages of rice crop. It was observed that application of herbicide butachlor decreased growth and N2-fixation of both native and inoculated cyanobacteria whereas insecticide metacid application was found to increase these attributes. The interaction of algal inoculation and both the biocides application were superior than algal inoculation with the herbicide application on both algae and rice. It is concluded from this study that herbicides application affected adversely cyanobacteria but insecticide application was favorable to them and application of both biocides was better than herbicide alone. Therefore judicious use of these chemicals and cyanobacteria in rice fields are suggested. © 2015, Springer Science+Business Media Dordrecht.
Decrypting the effect of sulfate stress on the cyanobacterium Anabaena sp. PCC 7120 using physiological, proteome and transcript analysis in conjunction with bioinformatics
(Elsevier B.V., 2024) Surbhi Kharwar; Arun Kumar Mishra
Sulfate limitation affects growth and various metabolic processes in cyanobacteria. However, there is little understanding of the underlying mechanism of these processes. Hence, the study investigated the effects of sulfate limitation in the cyanobacterium, Anabaena sp. PCC 7120. Results showed that sulfate stress affected photopigment contents in the test cyanobacterium delineating reduced growth. Proteome profile showed that differential expression profiles of different proteins involved in the various metabolic pathways suggested sulfur-dependent pathways were altered due to sulfate limitation. The most damaging effect was observed on the proteins belonging to the photosynthesis pathway, affirming the relationship between sulfur and carbon metabolism. Expression of proteins involved in the pathways such as nitrogen, protein synthesis, chaperone category, amino acid biosynthesis, and redox-responsive proteins were down-regulated. Moreover, forty-seven hypothetical proteins were also influenced by sulfate limitation. Molecular chaperones act as a physical barrier to prevent the aggregation of housekeeping proteins. Down expression of these proteins might affect the sustainability of the other proteins. Besides, transcript levels of the selected proteins were in concordance with physiological as well as proteome data. Additionally, template-based modeling and ab initio full atomic relaxation were performed via bioinformatic analysis through different tools to gain deeper insight into the structural and functional attributes of hypothetical proteins. Based on study, it could be concluded that mostly the proteins were downregulated which may lead to PCD in the cyanobacterium and also suggested that sulfur is a central hub and crucial for various sulfur-dependent pathways. © 2024 The Author(s)
Allergenicity of airborne cyanobacteria Phormidium fragile and Nostoc muscorum
(2008) Naveen Kumar Sharma; Ashwani K. Rai
In recent times, airborne microorganisms and their constituents have become prominent safety and health concern. Ongoing climatic changes coupled with unwarranted human activities have significantly deteriorated the ambient air quality. In certain environments, airborne algae contribute significantly to the total biological load of the atmosphere, hitherto dominated by bacteria and fungi. Present study was aimed to investigate the allergenic potency of two frequent viable algal forms i.e., Phormidium fragile and Nostoc muscorum found in the atmosphere of Varanasi City, India. To test the allergenic potency, crude extracts of these strains were subjected to intra-dermal allergy test and subsequent leukocyte counts, which revealed their allergenic nature. Both the species varied in their allergenic potency. N. muscorum appeared to be more allergenic than P. fragile. However, when the allergens were mixed in equal amounts, the severity of allergenicity increased significantly. A limited pattern of cross-reactivity between the species was also evident. © 2006 Elsevier Inc. All rights reserved.
Extraction, characterization and antioxidative potentials of UV-screening compound, mycosporine-like amino acids from epilithic cyanobacterium Lyngbya sp. HKAR − 15
(Springer Science and Business Media B.V., 2024) Abha Pandey; Nasreen Amin; Vinod K. Kannaujiya; Rajeshwar P. Sinha
Mycosporine-like amino acids (MAAs) are a unique class of UV-screening bioactive molecules with potent antioxidants and photoprotective properties, synthesized by various species of cyanobacteria in different habitats. The cyanobacterial biofilms play a crucial driver in the development of ecological communities. The current study examined the existence of the photoprotective MAAs in a novel epilithic cyanobacterium Lyngbya sp. strain HKAR-15 isolated from cyanobacterial biofilms on the rock surface. The isolated MAAs were identified, purified and characterized using UV-Vis spectroscopy, HPLC (High-Performance Liquid Chromatography), ESI-MS (Electrospray Ionization-Mass Spectrometry), FTIR (Fourier Transform Infrared Spectroscopy) and NMR (Nuclear Magnetic Resonance). The compounds were recognized as palythine (retention time (RT): 2.7 min; UV λmax: 320 nm; m/z: 245.02) and porphyra-334 (RT: 3.6 min; UV λmax: 334 nm; m/z: 347.1). FTIR spectroscopy analyses also revealed the presence of functional groups of both compounds. NMR spectroscopy analyses confirmed the presence of both palythine and porphyra-334. The UV-induced production of both MAAs was visualized under ultraviolet radiation (UVR) in contrast to the photosynthetically active radiation (PAR). The MAAs (palythine and porphyra-334) had a significant dose-dependent free radical scavenging capacity. The findings show that MAAs perform a dynamic role in the survival and photoprotection of cyanobacteria in hostile environments under high solar UV irradiances. These photoprotective compounds may have various biotechnological applications as well as role in the development of natural sunscreens. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.
Peculiar Endosymbiosis in the Cyanobiont Nostoc azollae 0708: An In Silico Approach
(Springer Nature, 2024) Minu Kesheri; Swarna Kanchan; Amit Kumar; Upasna Srivastava; Shivani Sharda; Bhagwan Malik; Tarun Mishra; Poonam Kaithal; Jitendra Narayan; Prashant Kumar; Prerna Priya; Rajeshwar P. Sinha
Nostoc azollae 0708 exhibits peculiar endosymbiosis owing to the unique commitment of cyanobiont’s association with fern throughout its life cycle. This chapter elaborates various in silico approaches adopted for intriguing proteomics aspects of Fe and Mn superoxide dismutase in the cyanobiont Nostoc azollae 0708. Prediction of physicochemical parameters elucidating molecular weight, isoelectric point (pI), instability index, aliphatic index, total no. of negatively charged residues (Asp + Glu), total no. of positively charged residues (Arg + Lys), extinction coefficient, and GRAVY are discussed in detail. Generating good quality 3D structural models for Fe-SOD and Mn-SOD by homology modeling and validation by Prosa-web, verify-3D, and PROCHECK is elaborately explained. Conservation of metal binding positions, domains, and motifs suggesting functional conservation, highly conserved exposed as well as buried amino acid residues advocating their structural and functional importance is also discussed. Generation of protein–protein interaction network using STRING illustrating the physical and functional interaction of superoxide dismutase with other proteins and biological cascade of these proteins in Nostoc azollae has been described. The NJ phylogenetic tree for Fe-SOD depicts Nostoc sp. PCC 7524 as the nearest evolutionary homolog, whereas Nostoc sp. PCC 7107 and Nostoc piscinale CENA 21 as evolutionary close homologs of Mn-SOD in Nostoc azollae. The present in silico methodologies discussed in this chapter may pave the way for further experimental validation aiding in exploring the biochemical, biotechnological, and biofertilizer potential of the cyanobiont recruited by the fern Azolla. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

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