Anabaena Laxa Research Articles

Green solutions: evaluating the impact of Chlorella sorokiniana and Anabaena laxa on captan phycoremediation

This study explores the use of algae for phycoremediation, focusing on how Chlorella sorokiniana and Anabaena laxa detoxify water contaminated with captan, a common fungicide. The efficiency of these species in absorbing captan and the associated biochemical changes were evaluated to assess their potential for environmental protection. Microalgae were exposed to captan concentrations of 15 and 30 mg/L, and various parameters, including captan uptake, chlorophyll (Chl) a, carotenoid levels, and changes in metabolic profiles (soluble carbohydrates, organic acids, amino acids, and fatty acids), were measured. Results showed Anabaena had a higher captan absorption capacity (141.7 µg/g at 15 mg/L and 239.3 µg/g at 30 mg/L) compared to Chlorella (74.43 µg/g and 162 µg/g). Increased captan uptake reduced the growth of both species, as indicated by lower Chl a levels. Both species accumulated osmo-protectants and antioxidants as defense mechanisms, with soluble sugars increasing by 83.49% in Chlorella and 68.87% in Anabaena, and carotenoids increasing by 60.42% and 46.24%, respectively. Principal component analysis revealed distinct species-level responses, with Anabaena showing greater tolerance. The study concludes that both species can effectively remediate captan, with Anabaena being more efficient, indicating their potential for mitigating agrochemical impacts in aquatic environments and promoting sustainable agriculture and water management.

Assessing thallium phycoremediation by applying Anabaena laxa and Nostoc muscorum and exploring its effect on cellular growth, antioxidant, and metabolic profile

Thallium (Tl), a key element in high-tech industries, is recognized as a priority pollutant by the US EPA and EC. Tl accumulation threatens aquatic ecosystems. Despite its toxicity, little is known about its impact on cyanobacteria. This study explores the biochemical mechanisms of Tl(I) toxicity in cyanobacteria, focusing on physiology, metabolism, oxidative damage, and antioxidant responses. To this end, Anabaena and Nostoc were exposed to 400 µg/L, and 800 µg/L of Tl(I) over seven days. Anabaena showed superior Tl(I) accumulation with 7.8% removal at 400 µg/L and 9.5% at 800 µg/L, while Nostoc removed 2.2% and 7.4%, respectively. Tl(I) exposure significantly reduced the photosynthesis rate and function, more than in Nostoc. It also altered primary metabolism, increasing sugar levels and led to higher amino and fatty acids levels. While Tl(I) induced cellular damage in both species, Anabaena was less affected. Both species enhanced their antioxidant defense systems, with Anabaena showing a 175.6% increase in SOD levels under a high Tl(I) dose. This suggests that Anabaena’s robust biosorption and antioxidant systems could be effective for Tl(I) removal. The study improves our understanding of Tl(I) toxicity, tolerance, and phycoremediation in cyanobacteria, aiding future bioremediation strategies.

Cyanobacterium priming of tomato and spinach nursery stimulates seedling vigor and yields

ABSTRACT Three cyanobacterial strains, Anabaena laxa C11, Nostoc carneum BF2, Anabaena doliolum BF4, producing plant growth promoting metabolites such as sugars, indole acetic acid and proteins were selected for priming seeds of three varieties of tomato and two of spinach, followed by nursery raising of seedlings in soil-less potting mixes. The performance of two tomato varieties NS2533 and NS4266, was superior, as compared to Jewel, with enhancement of 12% to 29% in terms of length and weight of root/shoots, as well as 76% more pigments. In tomato, Nostoc carneum BF2 was superior, closely followed by Anabaena laxa C11. Among the two Spinach varieties evaluated, Pusa All green responded with 15–20% significantly higher values of seedling traits, as compared to Mulayam. Vigor indices were significantly higher with the cyanobacterial priming treatments, with Anabaena laxa C11, showing 27% higher values, over control. Principal Component and Multivariate Analyses highlighted the significant correlation between chlorophyll and available N content of mix with biometrical and pigment-related attributes. Transplantation of best performing varieties of tomato -NS4266 and spinach -Pusa All green in climate-controlled polyhouse recorded significantly higher yields in the cyanobacterium-primed plants, over control. Such promising crop-cyanobacterium interactions can be explored for enhancing the productivity of nursery-raised vegetable crops.

Foliar application of cyanobacterial formulations stimulates plant growth and fruit quality in tomato under protected cultivation

ABSTRACT Cyanobacterial biofertilizers enhance plant and soil productivity across crops, through soil-seed application at the field level; however, their use as foliar treatment is less investigated. This study evaluated the role of foliar sprays, initiated 4 weeks after transplantation of nursery-raised seedlings in beds, and effected at weekly intervals for a period of eight weeks. towards enhancing plant growth, yield and quality of tomato grown in a climate-controlled polyhouse. Sprays were composed of aqueous formulations of carrier alone, and those amended with the formulations of plant-growth-promoting cyanobacterium Anabaena laxa (A. laxa) or biofilm Anabaena torulosa -Trichoderma viride (An-Tr) or suspension of 100 µM Fe EDTA. A. laxa brought about a significant increase in nitrate reductase and glutamine synthetase activity in leaves by 13%–17%, along with 3-fold stimulation in carbonic anhydrase activity. Cyanobacterium-amended foliar agents significantly enhanced soil dehydrogenase, urease activity, along with increments in organic carbon, Fe, Zn in soil and stimulated yield, fresh weight and quality of fruits. Both cyanobacterial formulations were promising in enhancing plant growth, fruit yield and quality, however, A. laxa also significantly improved microbiological activity and nutrient enrichment in soil. Future research is focused towards optimising the dose and storage life of such foliar agents for protected horticulture.

Elevated CO2modulates the metabolic machinery of cyanobacteria and valorizes its potential as a biofertilizer

Elevated CO2 is one of the drivers of global warming and cyanobacteria can be promising options to gainfully convert this to useful biomass. The present investigation was carried out to understand the metabolic changes underlying the C-N dynamics in two cyanobacteria- Anabaena laxa and Calothrix elenkinii grown under ambient CO2 (400 ± 50 ppm) and elevated CO2 (700 ± 50 ppm) environments. Total chlorophyll, phycobilins, proteins, IAA, total sugars, organic carbon, and total-N increased by 14–16% in both the cultures under elevated CO2. Under elevated CO2, the activity of C- and N-assimilation enzymes such as RuBisCO, nitrogenase, nitrate reductase, and glutamine synthetase were significantly enhanced by 20–28% and 18–25% in A. laxa and C. elenkinii respectively. Time course studies suggested that the C-N ratio increased both with the period of incubation and elevated CO2, and there was a significant response of the antioxidant machinery in both organisms. The profiles of fatty acid methyl esters (FAME) analysed using MetaboAnalyst 5.0, illustrated a significant increase in the saturated and branched fatty acids, with increasing age of both cultures, while carbocyclic fatty acids and unsaturated fatty acids enhanced distinctly under elevated CO2 in C. elenkinii and A. laxa respectively illustrating their adaptation and robust nature. Overall, elevated CO2 elicited a positive impact on N-fixation, C-assimilation, and biomass production in both cyanobacteria, thereby improving their suitability as a biofertilizer.

Influence of cyanobacterial inoculants, elevated carbon dioxide, and temperature on plant and soil nitrogen in soybean.

Climate change affects nitrogen dynamics in crops and diazotrophic microorganisms with carbon dioxide (CO2 ) sequestering potential such as cyanobacteria can be promising options. The interactions of three cyanobacterial formulations (Anabaena laxa, Calothrix elenkinii and Anabaena torulosa-Bradyrhizobium japonicum biofilm) on plant and soil nitrogen in soybean, were investigated under elevated CO2 and temperature conditions. Soybean plants were grown inside Open Top Chambers under ambient and elevated (550 ± 25 ppm) CO2 concentrations and elevated temperature (+2.5-2.8°C). Interactive effect of elevated CO2 and cyanobacterial inoculation through A. laxa and Anabaena torulosa-B. japonicum biofilm led to improved growth, yield, nodulation, nitrogen fixation, and seed N in soybean crop. Nitrogenase activity in nodules increased in A. laxa and biofilm treatments, with an increase of 55% and 72%, respectively, over no cyanobacterial inoculation treatment. Although high temperature alone reduced soil microbial biomass carbon, dehydrogenase activity, and soil available N, the combined effect of CO2 and temperature were stimulatory; cyanobacterial inoculation further led to an increase under all the conditions. The highest seed N uptake (758 mg plant-1 ) was recorded with cyanobacterial biofilm inoculation under elevated CO2 with control temperature conditions. The positive interactions of elevated CO2 and cyanobacterial inoculation, particularly through A. laxa and A. torulosa-B. japonicum biofilm inoculation highlights their potential in counteracting the negative impact of changing climate along with enhancing plant and soil N in soybean.

Cyanobacterial inoculation in elevated CO2 environment stimulates soil C enrichment and plant growth of tomato

The present study investigated the influence of cyanobacterial inoculants viz., Anabaena laxa (A.laxa) ), Calothrix elenkinii (C. elenkinii) and Anabaena torulosa- Trichoderma viride (An-Tr) under ambient (aCO2) and elevated (eCO2) conditions, on soil and plant parameters, when grown with/without tomato crop. Significant enhancement in soil chlorophyll, proteins, polysaccharide content, total leaf pigments and C-N assimilating enzyme activities was recorded under elevated CO2 conditions with cyanobacterial inoculation, when grown with/without tomato crop. Supplementation with A. laxa led to more than a fold-enhancement in polysaccharides and 40%–45% increment in available nitrogen, while An-Tr recorded 60%–70% increase in soil microbial biomass carbon under elevated CO2 condition. A. laxa treatment also recorded highest plant pigments, glutamine synthetase and carbonic anhydrase activity under elevated CO2 condition. Distinct influence of elevated CO2 condition, cyanobacterial inoculation and plant and their interactions were recorded. Interestingly, plants grown under elevated CO2 showed early flowering, by eight days, compared to ambient conditions. Phospholipid fatty acid profiles of soil samples illustrated significant changes in the total biomass and distribution of notional microbial groups due to inoculation and the presence of plant. Multivariate analyses illustrated the significant interactions among the soil and microbiological attributes, highlighting that cyanobacterial inoculation can be a promising intervention to utilize beneficially the elevated CO2 for enhancing soil nutrients, crop growth and productivity in tomato.

Fortifying nursery soil-less media with cyanobacteria for enhancing the growth of tomato

Priming nursery media to develop robust nurseries is a major objective of horticulturists for improving yields and quality of produce, and use of cyanobacteria, with both plant growth promoting and biofertilizing properties, can be valuable for generating robust nurseries of tomato. The potential of cyanobacteria as supplements to different soilless media combinations involving perlite, cocopeat and vermiculite (P,C,V) in different combinations was evaluated in terms of their ability to enhance the growth of tomato, from seed to fruiting stage. Agriculturally beneficial cyanobacterial cultures - Anabaena laxa, Calothrix elenkinii, and biofilm- Anabaena torulosa-Trichoderma viride (An-Tr) were used to augment these media and evaluated in Pro-Trays, pot and polyhouse beds respectively. Significant differences were recorded in terms of plant and media parameters. A positive correlation (r = 0.55, 0.78) between PEP carboxylase and Carbonic anhydrase enzyme activities was observed in Pro-Tray and polyhouse experiments. The performance of C:V + C. elenkinii, P:C:V + An-Tr, PM (Potting mix; C:V:P, 3:1:1) + A. laxa in terms of leaf, soil and nutrient data suggested their superiority among all other treatments. An enhancement of 14.70% and 36.55% in fruit and flower count was observed in PM + A. laxa over control. Among all the media evaluated, PM was most responsive to augmentation using any of the cultures, highlighting it as an effective nursery medium. A. laxa proved most superior among the cultures evaluated. Future research is focused on the upscaling the use of A. laxa as a nursery medium supplement for enhancing growth and productivity of tomato.

Immunomodulating polysaccharide complexes and antioxidant metabolites from Anabaena laxa, Oscillatoria limosa and Phormidesmis molle

The aim of the present study is to investigate the chemical composition and biological activity of polysaccharides (PSs) and secondary metabolites, isolated from poorly explored cyanobacterial species, in search of immunomodulating and antioxidant compounds. Polysaccharide complexes (PSCs) were obtained by boiling water extraction from biomasses of Anabaena laxa (AL-PSC), Oscillatoria limosa (OL-PSC) and Phormidesmis molle (PM-PSC), pretreated with 80% (v/v) ethanol and pure acetone. The total carbohydrate content in the complexes varies between 53.0% and 63.5% (w/w). The complexes contain PSs composed of neutral monosaccharides as main building blocks and the uronic acids (GalA and GlcA) are in smaller amounts (4.2–9.5%). AL-PSC and OL-PSC are rich in Glc (33.1% and 38.6%), followed by Man, Gal and Xyl as other dominant monomers. PM-PSC has the highest amount of Gal (45%), followed by Glc (21%). Additionally, a neutral exopolysaccharide (EPS) (PM-EPSC), from a (hetero)xylan type (Xyl content 70.5%), was isolated from P. molle. The weight-average molecular weights (Mw) of AL-PSC, OL-PSC and PM-PSC are estimated to be 67.0, 71.8 and 74.7 × 104 g/mol. AL-PSC (200 μg/mL) expresses the most potent ex vivo stimulating activity on human monocytes and granulocytes. AL-PSC and OL-PSC (50–200 μg/mL) manifest better in vitro growth-inhibitory effect against human colorectal adenocarcinoma (HT-29) and colon adenocarcinoma (LS-180) cells than PM-PSC, affecting their lysosomal activity. The organic extracts, obtained from the biomasses extracted with 80% ethanol and acetone, are rich in carbohydrates, followed by fatty acids and other triacylglycerol metabolism compounds, terpenes, Krebs cycle metabolites, chlorophylls and phenolics. Among the three species, the extract from A. laxa (AL-E) contains the highest phenolic content, as well as exhibiting the strongest antioxidant activity by the oxygen radical absorbance capacity (ORAC) assay. A. laxa and the other cyanobacteria should be considered valuable for isolation of immunomodulators and antioxidants with possible application in dietetics and medicine.

Exploring the potential of Aloe vera as a carrier for developing a novel cyanobacterial formulation

Cyanobacteria are commonly deployed as inoculants to enrich the nutrient status of soil and stimulate plant growth. For large scale application, easy to use formulations which can remain functionally viable during storage are required. In this context, the nutritive qualities of Aloe vera gel was explored to develop an aqueous formulation (AE), which was supplemented with a beneficial cyanobacterium Anabaena laxa (RPAN8), thereafter, referred to as AEC. Different inocula levels of 1, 2 and 5% were used to amend the graded dilutions (Pure, 1:1, 1:5, 1:10) of AE. Time course observations showed that all the dilutions supported cyanobacterial growth (as evident from increase in chlorophyll content) upto 70 days. Available phosphorus content of AE samples declined (28%) following cyanobacterial growth, indicating P utilization by the cyanobacterium. At all levels of inocula, growth was found to be higher (1.4–2 folds on 35th day of storage) in 1:10 dilution, as compared to lower dilutions or pure samples. Microscopy and PCR based analyses confirmed the presence of the inoculated cyanobacterium in the Aloe vera formulations (AEC). Most importantly, these formulations exhibited plant growth promoting trait, fungicidal activity and stimulated the germination of wheat and mustard seeds. This represents a novel approach exploring the useful qualities of Aloe vera to design a carrier for an agriculturally important cyanobacterium Anabaena laxa. The effective maintenance of the functional attributes of the cyanobacterium highlights its promise and the need for further refinement as an environment-friendly and phyto-beneficial option for farmers and entrepreneurs.

Dissipation of pyridaphenthion by cyanobacteria: Insights into cellular degradation, detoxification and metabolic regulation

Excessive use of organophosphorus pesticides such as pyridaphenthion (PY) to constrain insects induced crop loss, results in soil and water sources contamination. Cyanobacteria are sensitive biological indicators and promising tools for bioremediation of soil and water pollutants. To understand PY toxicity, detoxification and degradation in cyanobacteria, we performed a comparative study in the two diazotrophic cyanobacteria; Anabaena laxa and Nostoc muscorum. They were exposed to mild (5 mg/L) and high (10 mg/L) concentrations of PY for 7 days. Compared to A. laxa, N. muscorum efficiently showed high PY accumulation and degradation to a safe environmentally product; 6-hydroxy-2-phenylpyridazin-3(2 H)-one. PY inhibited cell growth and reduced Chl a content and photosynthesis related enzymes (PEPC and RuBisCo) activities in both species, but to less extend in N. muscorum. It also induced oxidative damage, particularly in A. laxa, as indicated by high H2O2, lipid peroxidation and protein oxidation levels and increased NADPH oxidase enzyme activity. N. muscorum invested more in antioxidants induction, i.e., induced ascorbate and glutathione cycle, however, these antioxidants increments in A. laxa were less pronounced. Overall, this study provides more in-deep insights into the PY toxicity and the role of N. muscorum as a promising PY remediator.

Prospecting the promise of cyanobacterial formulations developed using soil-less substrates as carriers

Abstract Cyanobacteria are widely used as biofertilizers and their effectiveness is influenced by the type of carrier, which in turn, dictates the viability of the inocula being introduced for improving plant growth. Soil-less substrates were explored as carriers in the present investigation; the potential of perlite (P), cocopeat (C) and vermiculite (V), individually and in combinations (1:1) such as — perlite: cocopeat, perlite: vermiculite, cocopeat: vermiculite, and perlite: cocopeat: vermiculite (1:1:1.) was screened. Four agriculturally beneficial cyanobacterial cultures/biofilms — Calothrix elenkinii, Anabaena laxa, Anabaena torulosa-T . viride (An-Tr) and A. torulosa-Bacillus sp. (An-Bs) were characterised and shelf-life evaluated after augmenting them to such substrates. Time course analyses after 2, 10 and 20 weeks illustrated that chlorophyll, as an index of photosynthetic biomass and population counts of the bacterial/fungal partner of biofilms enhanced significantly. For their use as disease suppressive options, fungicidal activity against phytopathogenic fungi was tested and found to be enhanced with the period of incubation. P: C and C:V were identified as most promising, and augmentation with cyanobacteria/biofilms showed significant cyanobacterial colonisation in the substrate after 20 weeks, illustrating their extended shelf-life. PCR amplification using 16S cyanobacterial, bacterial and fungal ITS directed primers confirmed the utility of these substrates. Seed germination test with maize, radish and wheat seeds showed marginal increases as a result of augmentation, with no phytotoxicity, and these novel mixes need to be tested in pot and field experiments as inoculants.

Differential responses of two cyanobacterial species to R-metalaxyl toxicity: Growth, photosynthesis and antioxidant analyses

Metalaxyl is a broad-spectrum chiral fungicide that used for the protection of plants, however extensive use of metalaxyl resulted in serious environmental problems. Thus, a study on the detoxification mechanism in algae/cyanobacteria and their ability for phycoremediation is highly recommended. Here, we investigated the physiological and biochemical responses of two cyanobacterial species; Anabaena laxa and Nostoc muscorum to R-metalaxyl toxicity as well as their ability as phycoremediators. Two different levels of R-metalaxyl, at mild (10 mg/L) and high dose (25 mg/L), were applied for one-week. We found that A. laxa absorbed and accumulated more intracellular R-metalaxyl compared to N. muscorum. R-metalaxyl, which triggered a dose-based reduction in cell growth, photosynthetic pigment content, and photosynthetic key enzymes’ activities i.e., phosphoenolpyruvate carboxylase (PEPC) and ribulose‒1,5‒bisphosphate carboxylase/oxygenase (RuBisCo). These decreases were significantly less pronounced in A. laxa. On the other hand, R-metalaxyl significantly induced oxidative damage markers, e.g., H2O2 levels, lipid peroxidation (MDA), protein oxidation and NADPH oxidase activity. However, these increases were also lower in A. laxa compared to N. muscorum. To alleviate R-metalaxyl toxicity, A. laxa induced the polyphenols, flavonoids, tocopherols and glutathione (GSH) levels as well as peroxidase (POX), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-s-transferase (GST) enzyme activities. On the contrary, the significant induction of antioxidants in N. muscorum was restricted to ascorbate, catalase (CAT) and ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) enzyme activities. Although A. laxa accumulated more R-metalaxyl, it experienced less stress due to subsequent induction of antioxidants. Therefore, A. laxa may be a promising R-metalaxyl phycoremediator. Our results provided basic data for understanding the ecotoxicology of R-metalaxyl contamination in aquatic habitats and the toxicity indices among cyanobacteria.

Development of Nutrient-Rich Media Through Cyanobacterial Amendment and Their Characterization

Exogenous addition of growth stimulants or other chemicals to soil-less medium is a common practice for enhancing biomass and productivity, and a promising amendment option can be cyanobacteria, a ubiquitous group of photosynthetic, plant growth promoting and agriculturally beneficial microorganisms, used as biofertilizers in agriculture. The performance of three nitrogen-fixing cyanobacterial cultures- Anabaena torulosa (BF1), Anabaena doliolum (BF4) and Anabaena laxa (RPAN8), through amendment to two media - namely rooting mix (cocopeat, vermiculite and perlite in 3:1:1) and sand contained in Pro-Trays was evaluated at fortnightly intervals up to 30 days. An enhancement, up to 2- to 3-fold in chlorophyll (as an index of photosynthetic biomass) and 30–45% IAA was observed in the extracts of cyanobacterium–amended media, over control; rooting mix was more promising as compared to sand. The addition of cyanobacteria also brought a significant enhancement of 30–40% in the availability of nitrogen and micronutrients–Mn, Cu, Zn and Fe in both media. Phytotoxicity studies with seeds of mustard, radish, maize and wheat, revealed no inhibition, highlighting the promise of these fortified rooting mixes as organic inputs in nursery propagation.

Co-cultivation of cyanobacteria for raising nursery of chrysanthemum using a hydroponic system

The present investigation aimed to utilize plant growth–promoting diazotrophic cyanobacteria as an option to raise the chrysanthemum varieties Pusa Aditya and Jaya in a nursery by co-culturing hydroponically. Fresh stem cuttings of chrysanthemum were planted in BG 11 medium (−N) which was inoculated to log-phase cultures of Anabaena torulosa (BF1), Anabaena doliolum (BF4), and Anabaena laxa (RPAN8) individually. Analyses of chrysanthemum growth and biometric/biochemical parameters after 30 days of co-cultivation revealed that co-culturing treatments performed significantly better, as compared with BG11 medium alone. Anabaena laxa brought about an increment of 27–40% in IAA production in the root tissues of both varieties grown in hydroponics. Quantification of biofilm formation on roots (measured as OD550) illustrated a two- to four-fold increment in the co-culture treatments. PEP carboxylase activity was significantly enhanced in root and shoot tissues of cuttings in Jaya, and the medium chlorophyll enhanced by several folds in both varieties. Significant increases in root dry biomass were recorded, which positively correlated with root protein (r = 0.992) in Pusa Aditya, illustrating the superiority of co-culturing as a promising option for nursery propagation. The economic benefits of BG 11 medium (without combined N) as a novel growth medium for growing the cyanobacterium and raising chrysanthemum nursery, in co-culturing mode, were also highlighted. Anabaena torulosa (BF1) performed well in both Pusa Aditya and Jaya, while Anabaena laxa (RPAN8) was significantly superior in Jaya. Future research is focused towards integration of such novel and cheap organic inputs in maintaining disease-free and nutrient-enriched plants in long-term experiments up to flowering stage.

Physiological and biochemical responses to aluminum-induced oxidative stress in two cyanobacterial species

Phycoremediation technologies significantly contribute to solving serious problems induced by heavy metals accumulation in the aquatic systems. Here we studied the mechanisms underlying Al stress tolerance in two diazotrophic cyanobacterial species, to identify suitable species for Al phycoremediation. Al uptake as well as the physiological and biochemical responses of Anabaena laxa and Nostoc muscorum to 7 days Al exposure at two different concentrations i.e., mild (100 μM) and high dose (200 μM), were investigated. Our results revealed that A. laxa accumulated more Al, and it could acclimatize to long-term exposure of Al stress. Al induced a dose-dependent decrease in photosynthesis and its related parameters e.g., chlorophyll content (Chl a), phosphoenolpyruvate carboxylase (PEPC) and Ribulose‒1,5‒bisphosphate carboxylase/oxygenase (RuBisCo) activities. The affect was less pronounced in A. laxa than N. muscorum. Moreover, Al stress significantly increased cellular membrane damage as indicated by induced H2O2, lipid peroxidation, protein oxidation, and NADPH oxidase activity. However, these increases were lower in A. laxa compared to N. muscorum. To mitigate the impact of Al stress, A. laxa induced its antioxidant defense system by increasing polyphenols, flavonoids, tocopherols and glutathione levels as well as peroxidase (POX), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPX) enzymes activities. On the other hand, the antioxidant increases in N. muscorum were only limited to ascorbate (ASC) cycle. Overall, high biosorption/uptake capacity and efficient antioxidant defense system of A. laxa recommend its feasibility in the treatment of Al contaminated waters/soils.

Exploring Crop–Microbiome Interactions Towards Improving Symbiotic Performance of Chickpea (Cicer arietinum) Cultivars Using Cyanobacterial Inoculants

The significance of integrated nutrient management practices is well established in improving the productivity of chickpea (Cicer arietinum); however, the effects of the inoculation of cyanobacterial inoculants on nodule metabolism, microbiome and associated genes are less explored. In the present investigation, cyanobacterium Anabaena laxa (A. laxa) and biofilm developed using Anabaena torulosa, with Mesorhizobium ciceri as a partner (An-M. ciceri), were evaluated along with Mesorhizobium ciceri (M. ciceri) alone, in three chickpea cultivars. Microbial inoculation led to 40–70% enhancement in nitrogen fixation, leghaemoglobin and ureide content, and two- to threefold increment in nitrate reductase and phosphoenolpyruvate carboxylase activity of the nodules. An enhancement of 30–50% in the soil available macro- and micronutrients and plant growth attributes was also observed. A significant correlation between the soil microbiological and plant parameters was recorded, particularly in relation to the nitrogen dynamics. Increases in the leghaemoglobin content in nodules due to An-M. ciceri, A. laxa and M. ciceri ranged from 18 to 40%, particularly in chickpea cv. BG372 in which 60–80% enhancement was recorded. Whereas the nifH gene copies in the nodule tissues ranged from 5.00 × 106 to 3.35 × 107 g−1, the application of A. laxa led to higher abundances of nifH gene copies in desi chickpea cv. BG372 and kabuli BG1053 cultivars. An-M. ciceri, followed closely by A. laxa, was the top-ranking treatment, and chickpea cv. BG372 was the best performing cultivar; An-M. ciceri—chickpea cv. BG372 proved to be the superior combination for higher plant growth and soil nutrient-related traits.

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness

BackgroundChalcones are the biogenetic precursors of all known flavonoids, which play an essential role in various metabolic processes in photosynthesizing organisms. The use of whole cyanobacteria cells in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone, is reported. The prokaryotic microalgae cyanobacteria are known to produce phenolic compounds, including flavonoids, as natural components of cells. It seems logical that organisms producing such compounds possess a suitable “enzymatic apparatus” to carry out their biotransformation. Therefore, determination of the ability of whole cells of selected cyanobacteria to carry out biocatalytic transformations of chalcone, the biogenetic precursor of all known flavonoids, was the aim of our study.ResultsChalcone was found to be converted to dihydrochalcone by all examined cyanobacterial strains; however, the effectiveness of this process depends on the strain with biotransformation yields ranging from 3% to >99%. The most effective biocatalysts are Anabaena laxa, Aphanizomenon klebahnii, Nodularia moravica, Synechocystis aquatilis (>99% yield) and Merismopedia glauca (92% yield). The strains Anabaena sp. and Chroococcus minutus transformed chalcone in more than one way, forming a few products; however, dihydrochalcone was the dominant product. The course of biotransformation shed light on the pathway of chalcone conversion, indicating that the process proceeds through the intermediate cis-chalcone. The scaled-up process, conducted on a preparative scale and by using a mini-pilot photobioreactor, fully confirmed the high effectiveness of this bioconversion. Moreover, in the case of the mini-pilot photobioreactor batch cultures, the optimization of culturing conditions allowed the shortening of the process conducted by A. klebahnii by 50% (from 8 to 4 days), maintaining its >99% yield.ConclusionsThis is the first report related to the use of whole cells of halophilic and freshwater cyanobacteria strains in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone. The total bioconversion of chalcone in analytical, preparative, and mini-pilot scales of this process creates the possibility of its use in the food industry for the production of natural sweeteners.

Formation of Variously Shaped Gold Nanoparticles by Anabaena laxa

Anew aspect of this study is the biocatalysis ability of Anabaena laxa—fresh-water strain—which to date has not been studied with respect to the formation of gold nanoparticles. The results of our study have shown that A. laxa is able to form gold nanoparticles (AuNPs) at good yields within 24 h of incubation at all three tested concentrations (0.1, 0.5 and 1 mM) of hydrogen tetrachloroaurate (III). After 24 h, nanoparticles were mostly localized in the growth medium, which significantly facilitates their isolation. However, the elongation of this process is accompanied by their concentration in the exopolysaccharide (EPS) layer of the cyanobacterial cells. There is a correlation between the initial concentration of the Au3+ cations and the formation of AuNPs of various shapes and a size. The comparison of activities of living and deactivated cells indicated that AuNPs were formed more efficiently when metabolically active cyanobacteria were used.

Cyanobacterial and rhizobial inoculation modulates the plant physiological attributes and nodule microbial communities of chickpea.

The present investigation aimed to understand the influence of two plant growth promoting cyanobacterial formulations (Anabaena-Mesorhizobium ciceri biofilm and Anabaena laxa), along with Mesorhizobium ciceri, on the symbiotic performance of five each of desi- and kabuli-chickpea cultivars. Inoculation with cyanobacterial formulations led to significant interactions with different cultivars, in terms of fresh weight and number of nodules, the concentration of nodular leghemoglobin, and the number of pods. The inoculant A. laxa alone was superior in its performance, recording 30-50% higher values than uninoculated control, and led to significantly higher nodule number per plant and fresh root weight, relative to the M. ciceri alone. Highest nodule numbers were recorded in the kabuli cultivars BG256 and BG1003. The kabuli cultivar BG1108 treated with the biofilmed Anabaena-M. ciceri inoculant recorded the highest concentration of leghemoglobin in nodules. These inoculants also stimulated the elicitation of defense- and pathogenesis-related enzymes in both the desi and kabuli cultivars, by two to threefolds. The analyses of Denaturing Gradient Gel Electrophoresis (DGGE) profiles revealed that microbial communities in nodules were highly diverse, with about 23 archaeal, 9 bacterial, and 13 cyanobacterial predominant phylotypes observed in both desi and kabuli cultivars, and influenced by the inoculants. Our findings illustrate that the performance of the chickpea plants may be significantly modulated by the microbial communities in the nodule, which may contribute towards improved plant growth and metabolic activity of nodules. This emphasizes the promise of cyanobacterial inoculants in improving the symbiotic performance of chickpea.