Assessing the Impact of Hexavalent Chromium (Cr VI) at Varied Concentrations on Spirulina platensis for Growth, Metal Sorption, and Photosynthetic Responses.

Spirulina platensis, a photosynthetic cyanobacterium, has garnered attention for its potential role in environmental remediation due to its ability to absorb and metabolize toxic heavy metals. Understanding its response toward toxicity of one of the most common contaminants, Cr(VI) is crucial for assessing its efficacy in bioremediation efforts. This study aims to investigate the physiological and biochemical responses of Spirulina platensis to varying concentrations of Cr(VI) from 0.5 to 5 ppm, shedding light on its potential as a bioindicator for environmental contamination and its suitability for bioremediation purposes. The impact of Cr(VI) on cell density, biosorption, pigment levels, nutrient content, fluorescence response, and photosynthetic efficiency was examined. The study revealed a gradual reduction in cell density, biomass production, and biosorption efficiency with increasing Cr(VI) concentrations. Pigment levels, carbohydrate, protein, and lipid content showed significant decreases, indicating physiological stress. Fluorescence response and photosynthetic efficiency were also adversely affected, suggesting alterations in electron transfer dynamics. A threshold for chromium toxicity was observed at 0.5 ppm, beyond which significant physiological disturbances occurred. This investigation highlights the sensitivity of Spirulina platensis to Cr(VI) toxicity and its potential as a bioindicator for heavy metal contamination. Metal sorption was highest in 0.5 ppm Cr(VI) with 56.56% removal. Notably, at lower concentrations, Cr(VI) acted as an intermediate electron acceptor, enhancing the electron transport chain and potentially increasing biomass under controlled conditions. The findings underscore the importance of understanding the mechanisms underlying heavy metal stress in microalgae for effective environmental remediation strategies. The research highlights the dual role of chromium(VI) in influencing S. platensis, depending on the concentration, and underscores the importance of understanding metal ion interactions with photosynthetic organisms for potential applications in bioremediation.

Bio Prospecting of Endophytes and PGPRs in Artemisinin Production for the Socio-economic Advancement.

The growing demand for Artemisia annua plants in healthcare, food, and pharmaceutical industries has led to increased cultivation efforts to extract a vital compound, Artemisinin. The efficacy of Artemisinin as a potent drug against malaria disease is well established but its limited natural abundance. However, the common practice of using chemical fertilizers for maximum yield has adverse effects on plant growth, development, and the quality of phytochemicals. To address these issues, the review discusses the alternative approach of harnessing beneficial rhizosphere microbiota, particularly plant growth-promoting rhizobacteria (PGPR). Microbes hold substantial biotechnological potential for augmenting medicinal plant production, offering an environmentally friendly and cost-effective means to enhance medicinal plant production. This review article aims to identify a suitable endophytic population capable of enabling Artemisia sp. to thrive amidst abiotic stress while simultaneously enhancing Artemisinin production, thereby broadening its availability to a larger population. Furthermore, by subjecting endophytes to diverse combinations of harsh conditions, this review sheds light on the modulation of essential artemisinin biosynthesis pathway genes, both up regulated and down regulated. The collective findings suggest that through the in vitro engineering of endophytic communities and their in vivo application to Artemisia plants cultivated in tribal population fields, artemisinin production can be significantly augmented. The overall aim of this review to explore the potential of harnessing microbial communities, their functions, and services to enhance the cultivation of medicinal plants. It outlines a promising path toward bolstering artemisinin production, which holds immense promise in the fight against malaria.

Evaluation of carbon capture in competent microalgal consortium for enhanced biomass, lipid, and carbohydrate production.

Enrichment of carbon dioxide (CO2) in environment is a major factor for enhancement of global warming on Earth surface. Microalgal consortia play an important role in inhibiting the alarming fluxes of CO2 through sustainable mechanism of bioconversion of CO2 into biomass. In the present investigation, eight heterogeneous consortia of cyanobacteria and green algae such as MC1, MC2, MC3, MC4, MC5, MC6, MC7, and MC8 for the sustainable utilization of effective CO2 sequestration and biomass production were studied. Two factorial central composite designs (% CO2 and pH) were used for optimization of cellular morphology, growth, and development of consortia. The photosynthetic quantum yield of consortium MC8 was found to be maximum (0.61) in comparison with other consortia. The morphological and physiological behavior of the above consortium was analyzed under C, 5, 10, and 15% concentrations of CO2 resource capture in 250 mL BG-11+ medium. We have identified that 10% CO2 concentrated medium maximally promoted the cellular growth in terms of cell dimension, dried biomass, carbohydrate, and lipid contents in this consortium. As such, the elemental composition of carbon and carbon capturing capability was high at 10% CO2 concentration. However, further CO2 enrichment (15%) led to decline in growth and morphology of cell size as compared to control. The results indicate that the optimum CO2 enrichment in consortia exhibits potent commercial utilization for rapid biomass production and plays a distinguished role in global carbon sequestration and mitigation agent.

Microalgal consortia differentially modulate progressive adsorption of hexavalent chromium.

A set of experiments was conducted to provide significant insights of micro-algal consortia regarding chromium adsorption. Four monocultures; Scenedesmus dimorphus, Chlorella sp., Oscillatoria sp., and Lyngbya sp., and their synthetic consortia were evaluated initially for chromium bio-adsorption at four different regimes of hexavalent chromium i.e. 0.5, 1.0, 3.0 and 5.0 ppm. Based on findings, only 1.0 and 5.0 ppm were considered for future experiments. Consequently, three different types of monoculture and consortia cells namely; live cells, heat-killed cells, and pre-treated cells were prepared to enhance their adsorption potential. Maximal adsorption of 112% was obtained at the dose of 1.0 ppm with 0.1% SDS pre-treated consortia cells over live consortia cells. In support, atomic absorption spectroscopy, laser induced breakdown spectroscopy, pulse amplitude modulated chlorophyll fluorescence, and scanning electron microscopy were performed to assess the structural and functional changes within consortia and their utilization in mitigation of elevated chromium levels.

Elucidating hydrogenase surfaces and tracing the intramolecular tunnels for hydrogenase inhibition in microalgal species.

Intramolecular tunnels are majorly attracting attention as possible pathways for entry of inhibitors like oxygen and carbon monoxide to the active sites of the enzymes, hydrogenases. The results of homology modeling of the HydSL protein, a NiFe-hydrogenase from Chlamydomonas reinhardtii and Chlorella vulgaris are presented in this work. Here we identify and describe molecular tunnels observed in HydSL hydrogenase enzyme systems. The possible determinant of the oxygen stability of already studied hydrogenases could be the lack of several intramolecular tunnels. The possible tunnels were traced out using MOLE 2 software, which showed several intramolecular pathways that may be connecting the active sites of the enzyme. The RMSD value showed a great deal of significance in the enzyme homology. This is the first report of its kind in which mapping of the intramolecular tunnels in the four-hydrogenase enzymes disclosed potential variations between designed models and acknowledged structures. We are seeking out the explanations for oxygen sensitivity of studied hydrogenases within the structure of intramolecular tunnels. Local and Global RMSD (Root mean square deviation) was calculated for models and templates, which showed value of 1.284 indicating a successful homology model. The tunnel tracing study by Mole 2 indicated two tunnels joined into one in C. reinhardtii model whereas C. vulgaris model showed one tunnel almost like two tunnels. Templates of both the A. vinosum and D. vulgaris hydrogenase consisted of six tunnels. For HydSL from Chlamydomonas and Chlorella Species the maximal potential was set to 250 kcal/mol (1,046 kJ/mol) and the positive potential areas were marked. Electrostatic studies define electrostatic potential (ESP) that help shuttle protons to the active site.

Evaluation of promising algal strains for sustainable exploitation coupled with CO2 fixation.

The photosynthetic activity of three microalgae, Chlamydomonas reinhardtii, Chlorella AU1, Scenedesmus AU1, and six cyanobacteria, Spirulina platensis, Anabaena cylindrica, Oscillatoria AU1, Nostoc muscurum, Synechococcus AU1, Synechocystis sp. PCC6803, was investigated. Strains S. platensis, Scenedesmus AU1 sp. and Chlorella AU1 sp. showed the highest fluorescence quenching than other strains tested. Thus, these were selected for CO2 mitigation analysis in a designed tubular photobioreactor system at 0.06%, 6%, 12%, 18% and 24% CO2 concentrations. Spirulina showed maximum biomass productivity of 1.03 g L(-1) d(-1) with the highest CO2 fixation rate of 0.678 g [Formula: see text] L(-1) d(-1) at 6% CO2 concentration. The maximum protein content (66.63%) was also achieved in Spirulina sp. at 6% CO2 concentration. Thus, Spirulina could be utilized as a source of protein supplement coupled with CO2 fixation. Maximum carbohydrate proportion (51.71%) was noted with Scenedesmus AU1 sp. at 12% CO2. Scenedesmus AU1 sp. also accumulated the maximum lipid content (25.07%) at 6% CO2 concentration, which was further analysed for biodiesel production. The extracted Scenedesmus oil was mainly rich in short chain fatty acids (C-16 : 0, C-18:1, C-18:2, C-18:3) which is an ideal combination for efficient biodiesel. Thus, this is vital in helping to choose Scenedesmus as a biodiesel feedstock, coupled with CO2 fixation.