Nostoc entophytum cell response to cadmium exposure: A possible role of chaperon proteins GroEl and HtpG in cadmium-induced stress

Study of pesticidal activity of bioactive compounds of Neowestiellopsis persica strain A1387 in improving the antioxidative and antimicrobial activity of wheat to sunn pest

Cyanobacteria have been recognized for their advantageous impact on plant growth and development. The application of certain techniques has the potential to enhance various aspects of plant development, including growth, yield, proximate content (such as protein and carbohydrate levels), as well as the ability to withstand abiotic stresses such as herbicide exposure. The current investigation focused on examining the influence of bioactive compounds derived from the cyanobacterium Neowestiellopsis persica strain A1387 on enhancing the antioxidant and anyimicrobial activity of wheat plants in their defense against the plant pathogenic Sunn pest. The findings of the study indicate that the levels of H2O2 and GPx in wheat plants that were infected with aphids were significantly elevated compared to the treatments where aphids and cyanobacteria extract were present. The confirmation of these results was achieved through the utilization of confocal and fluorescent microscope tests, respectively. Furthermore, the findings indicated that the constituents of the cyanobacterial extract augmented the plant's capacity to withstand stress by enhancing its defense mechanisms. In a broader context, the utilization of cyanobacterial extract demonstrated the ability to regulate the generation and impact of oxygen (O2) and hydrogen peroxide (H2O2), while concurrently enhancing the functionality of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) enzymes within wheat plants. This facilitation enabled the plants to effectively manage oxidative stress. Moreover, the findings of the antibacterial activity assessment conducted on the extract derived from cyanobacteria demonstrated notable susceptibility. The bacteria that exhibited the highest sensitivity to the extract of cyanobacterium Neowestiellopsis persica strain A1387 were staphylococcus aureus and pseudomonas aeruginosa. Conversely, salmonella typhi demonstrated the greatest resistance to the aforementioned extract. The potential impact of cyanobacteria extract on the antioxidative response of wheat plants to sunn pest infestation represents a novel contribution to the existing body of knowledge on the interaction between wheat plants and aphids.

The lysine 2-hydroxyisobutyrylome of Helicobacter pylori: Indicating potential roles of lysine 2-hydroxyisobutyrylation in the bacterial metabolism

Helicobacter pylori (H. pylori) is a pathogen which colonizes the stomach, causing ulcers, chronic gastritis and other related diseases. Protein post-translational modifications (PTMs) in bacteria mainly include glycosylation, ubiquitination, nitrosylation, methylation, phosphorylation and acetylation, all of which have divergent functions in the physiology and pathology of the bacterium. Lysine 2-hydroxyisobutyrylation (Khib) is a newly discovered type of PTM in recent years in some kinds of organisms, and this PTM is involved in the regulation of a variety of metabolic process, such as bacterial glucose metabolism, lipid metabolism and protein synthesis. This study performed the first qualitative lysine 2-hydroxyisobutyrylome in H. pylori, and a total of 4419 Khib sites in 812 proteins were identified. The results show that Khib sites are mainly located in the key functional regions or active domains of proteins involved in nickel-trafficking, energy production, virulence factors, anti-oxidation, metal resistance, and ribosome biosynthesis in H. pylori. The study presented here provides new hints in the metabolism and pathology of H. pylori and the proteins with Khib modification may be potentially promising targets for the further development of antibiotics, especially considering the high occurrence of treatment failure of H. pylori failure due to development of antibiotics-resistance.

Single and combined effects of polystyrene nanoplastics and Cd on submerged plants Ceratophyllum demersum L

Nanoplastics (NPs) and heavy metals are widely distributed in aquatic ecosystem, posing a potential threat to ecosystem function. Submerged macrophytes play an important role in water purification and maintaining ecological functions. However, the coupled effects of NPs and cadmium (Cd) on submerged macrophytes physiology and the mechanisms involved are still unclear. Here, the potential effects of single and co-Cd/PSNPs exposure on Ceratophyllum demersum L. (C. demersum) were explored. Our results showed that NPs aggravated the inhibition of Cd on plant growth ate (a decrease of 35.54 %), reduced chlorophyll synthesis (a decrease of 15.84 %), and disrupted the antioxidant enzyme system (a decrease of 25.07 % on SOD activity) of C. demersum. Massive PSNPs adhered to the surface of C. demersum when exposed to co-Cd/PSNPs while they did not adhere when exposed to single-NPs. The metabolic analysis further demonstrated that co-exposure down-regulated plant cuticle synthesis and that Cd exacerbated the physical damage and shadowing effects of NPs. In addition, co-exposure upregulated pentose phosphate metabolism, leading to the accumulation of starch grains. Furthermore, PSNPs reduced Cd enrichment capacity of C. demersum. Our results unraveled distinct regulatory networks for submerged macrophytes exposed to single and composite of Cd and PSNPs, providing a new theoretical basis for assessing the risks of heavy metals and NPs in the freshwater environment.

Emerging Trends of Nanotechnology and Genetic Engineering in Cyanobacteria to Optimize Production for Future Applications

Nanotechnology has the potential to revolutionize various fields of research and development. Multiple nanoparticles employed in a nanotechnology process are the magic elixir that provides unique features that are not present in the component's natural form. In the framework of contemporary research, it is inappropriate to synthesize microparticles employing procedures that include noxious elements. For this reason, scientists are investigating safer ways to produce genetically improved Cyanobacteria, which has many novel features and acts as a potential candidate for nanoparticle synthesis. In recent decades, cyanobacteria have garnered significant interest due to their prospective nanotechnological uses. This review will outline the applications of genetically engineered cyanobacteria in the field of nanotechnology and discuss its challenges and future potential. The evolution of cyanobacterial strains by genetic engineering is subsequently outlined. Furthermore, the recombination approaches that may be used to increase the industrial potential of cyanobacteria are discussed. This review provides an overview of the research undertaken to increase the commercial avenues of cyanobacteria and attempts to explain prospective topics for future research.

Time-Dependent Toxicity and Health Effects Mechanism of Cadmium to Three Green Algae

As algae are extremely sensitive to heavy-metal ions and can be critical biological indicators in the heavy-metal toxicity analyses conducted by environmental health researchers, this paper explores the sensitivity to temporal toxicity of three species of green algae: Scenedesmus obliquus, Chlorella pyrenoidosa, and Selenastrum capricornutum. The method of time-dependent microplate toxicity analysis was used to systematically investigate the changes in the toxicities of the three green-algae species induced by different concentrations of cadmium (Cd). The chlorophyll a content, antioxidant enzyme activity, and malondialdehyde (MDA) content in the algae were analyzed to explore the mechanism of Cd toxicity after 96 h of exposure. The results showed that the toxic effects of Cd on the three algae species were time-dependent. By comparing the toxic effect of Cd, indicated by pEC₅₀ (the negative logarithm of EC₅₀), on the algae species at four durations of exposure (24, 48, 72, and 96 h), this study found that the indicator organisms had different sensitivities to Cd. The order of sensitivity was C. pyrenoidosa > S. obliquus > S. capricornutum. Cd exposure had significant effects on the chlorophyll a and MDA content and on the enzyme activity of superoxide dismutase (SOD) and catalase (CAT) in the algae species. The chlorophyll a content in the cells of the algae decreased with increasing Cd concentration. The enzyme activity of CAT and content of MDA increased with increasing Cd concentration, which indicated that Cd had an oxidative stress effect on the three algae species.

Genomic and proteomic insights into the heavy metal bioremediation by cyanobacteria

Heavy metals (HMs) pose a global ecological threat due to their toxic effects on aquatic and terrestrial life. Effective remediation of HMs from the environment can help to restore soil's fertility and ecological vigor, one of the key Sustainable Development Goals (SDG) set by the United Nations. The cyanobacteria have emerged as a potential option for bioremediation of HMs due to their unique adaptations and robust metabolic machineries. Generally, cyanobacteria deploy multifarious mechanisms such as biosorption, bioaccumulation, activation of metal transporters, biotransformation and induction of detoxifying enzymes to sequester and minimize the toxic effects of heavy metals. Therefore, understanding the physiological responses and regulation of adaptation mechanisms at molecular level is necessary to unravel the candidate genes and proteins which can be manipulated to improve the bioremediation efficiency of cyanobacteria. Chaperons, cellular metabolites (extracellular polymers, biosurfactants), transcriptional regulators, metal transporters, phytochelatins and metallothioneins are some of the potential targets for strain engineering. In the present review, we have discussed the potential of cyanobacteria for HM bioremediation and provided a deeper insight into their genomic and proteomic regulation of various tolerance mechanisms. These approaches might pave new possibilities of implementing genetic engineering strategies for improving bioremediation efficiency with a future perspective.

Phycoremediation of contaminated water by cadmium (Cd) using two cyanobacterial strains (Trichormus variabilis and Nostoc muscorum)

Background

Water pollution with heavy metals is a severe dilemma that concerns the whole world related to its risk to natural ecosystems and human health. The main objective was to evaluate the removal efficiency of Cd of various concentrations from contaminated aqueous solution by use of two cyanobacterial strains (Nostoc muscorum and Trichormus variabilis). For this purpose, a specially designed laboratory pilot-scale experiment was conducted using these two cyanobacterial strains on four different initial concentrations of Cd (0, 0.5, 1.0 and 2.0 mg L−1) for 21 days.

Results

N. muscorum was more efficient than T. variabilis for removing Cd (II), with the optimum value of residual Cd of 0.033 mg L−1 achieved by N. muscorum after 21 days with initial concentration of 0.5 mg L−1, translating to removal efficiency of 93.4%, while the residual Cd (II) achieved by T. variabilis under the same conditions was 0.054 mg L−1 (89.13% removal efficiency). Algal growth parameters and photosynthetic pigments were estimated for both cyanobacterial strains throughout the incubation period.

Conclusions

High Cd concentration had a more toxic impact on algal growth. The outcomes of this study will help to produce treated water that could be reused in agrarian activities.

New Provisional Function of OmpA from Acinetobacter sp. Strain SA01 Based on Environmental Challenges

Acinetobacter OmpA is known as a multifaceted protein with multiple functions, including emulsifying properties. Bioemulsifiers are surface-active compounds that can disperse hydrophobic compounds in water and help increase the bioavailability of hydrophobic hydrocarbons to be used by degrading microorganisms.

An outer membrane protein A (OmpA) from Acinetobacter sp. strain SA01 was identified and characterized in-depth based on the structural and functional characteristics already known of its homologues. In silico structural studies showed that this protein can be a slow porin, binds to peptidoglycan, and exhibits emulsifying properties. Characterization of the recombinant SA01-OmpA, based on its emulsifying properties, represented its promising potentials in biotechnology. Also, the presence of SA01-OmpA in outer membrane vesicles (OMV) and biofilm showed that this protein, like its homologues in Acinetobacter baumannii, can be secreted into the extracellular environment through OMVs and play a role in the formation of biofilm. After ensuring the correct selection of the protein of interest, the role of oxidative stress induced by cell nutritional parameters (utilization of specific carbon sources) on the expression level of OmpA was carefully studied. For this purpose, the oxidative stress level of SA01 cell cultures in the presence of three nonrelevant carbon sources (sodium acetate, ethanol, and phenol) was examined under each condition. High expression of SA01-OmpA in ethanol- and phenol-fed cells with higher levels of oxidative stress than acetate suggested that oxidative stress could be a substantial factor in the regulation of SA01-OmpA expression. The significant association of SA01-OmpA expression with the levels of oxidative stress induced by cadmium and H₂O₂, with oxidative stress-inducing properties and lack of nutritional value, confirmed that the cells tend to harness their capacities with a possible increase in OmpA production. Collectively, this study suggests a homeostasis role for OmpA in Acinetobacter sp. SA01 under oxidative stress besides assuming many other roles hitherto attributed to this protein.

IMPORTANCEAcinetobacter OmpA is known as a multifaceted protein with multiple functions, including emulsifying properties. Bioemulsifiers are surface-active compounds that can disperse hydrophobic compounds in water and help increase the bioavailability of hydrophobic hydrocarbons to be used by degrading microorganisms. In this study, an OmpA from Acinetobacter sp. SA01 was identified and introduced as an emulsifier with a higher emulsifying capacity than Pseudomonas aeruginosa rhamnolipid. We also showed that the expression of this protein is not dependent on the nutritional requirements but is more influenced by the oxidative stress caused by stressors. This finding, along with the structural role of this protein as a slow porin or its role in OMV biogenesis and biofilm formation, suggests that this protein can play an important role in maintaining cellular homeostasis under oxidative stress conditions. Altogether, the present study provides a new perspective on the functional performance of Acinetobacter OmpA, which can be used both to optimize its production as an emulsifier and a target in the treatment of multidrug-resistant strains.

Microbial Cd(II) and Cr(VI) resistance mechanisms and application in bioremediation

The heavy metals cadmium (Cd) and chromium (Cr) are extensively used in industry and result in water and soil contamination. The highly toxic Cd(II) and Cr(VI) are the most common soluble forms of Cd and Cr, respectively. They enter the human body through the food chain and drinking water and then cause serious illnesses. Microorganisms can adsorb metals or transform Cd(II) and Cr(VI) into insoluble or less bioavailable forms, and such strategies are applicable in Cd and Cr bioremediation. This review focuses on the highlighting of novel achievements on microbial Cd(II) and Cr(VI) resistance mechanisms and their bioremediation applications. In addition, the knowledge gaps and research perspectives are also discussed in order to build a bridge between the theoretical breakthrough and the resolution of Cd(II) and Cr(VI) contamination problems.

Similarities and Differences in the Effects of Toxic Concentrations of Cadmium and Chromium on the Structure and Functions of Thylakoid Membranes in Chlorella variabilis

Trace metal contaminations in natural waters, wetlands, and wastewaters pose serious threats to aquatic ecosystems-mainly via targeting microalgae. In this work, we investigated the effects of toxic amounts of chromium and cadmium ions on the structure and function of the photosynthetic machinery of Chlorella variabilis cells. To halt the propagation of cells, we used high concentrations of Cd and Cr, 50-50 mg L-1, in the forms of CdCl2 x 2.5 H2O and K2Cr2O7, respectively. Both treatments led to similar, about 50% gradual diminishment of the chlorophyll contents of the cells in 48 h, which was, however, accompanied by a small (~10%) but statistically significant enrichment (Cd) and loss (Cr) of ß-carotene. Both Cd and Cr inhibited the activity of photosystem II (PSII)-but with more severe inhibitions with Cr. On the contrary, the PsbA (D1) protein of PSII and the PsbO protein of the oxygen-evolving complex were retained more in Cr-treated cells than in the presence of Cd. These data and the higher susceptibility of P700 redox transients in Cr-treated cells suggest that, unlike with Cd, PSII is not the main target in the photochemical apparatus. These differences at the level of photochemistry also brought about dissimilarities at higher levels of the structural complexity of the photosynthetic apparatus. Circular dichroism (CD) spectroscopy measurements revealed moderate perturbations in the macro-organization of the protein complexes-with more pronounced decline in Cd-treated cells than in the cells with Cr. Also, as reflected by transmission electron microscopy and small-angle neutron scattering, the thylakoid membranes suffered shrinking and were largely fragmented in Cd-treated cells, whereas no changes could be discerned with Cr. The preservation of integrity of membranes in Cr-treated cells was most probably aided by high proportion of the de-epoxidized xanthophylls, which were absent with Cd. It can thus be concluded that beside strong similarities of the toxic effects of Cr and Cd, the response of the photosynthetic machinery of C. variabilis to these two trace metal ions substantially differ from each other-strongly suggesting different inhibitory and protective mechanisms following the primary toxic events.