Cyanobacterial toxins: Modes of actions, fate in aquatic and soil ecosystems, phytotoxicity and bioaccumulation in agricultural crops

The monocyclic heptapeptides microcystins (MCs), are a group of hepatotoxins, produced worldwide by some bloom-forming cyanobacterial species/strains both in marine and freshwater ecosystems. MCs are synthesized non-ribosomally by large multi-enzyme complexes consisting of different modules including polyketide synthases and non-ribosomal peptide synthetases, as well as several tailoring enzymes. More than 85 different variants of MCs have been reported to exist in nature. These are chemically stable, but undergo bio-degradation in natural water reservoirs. Direct or indirect intake of MCs through the food web is assumed to be a highly exposed route in risk assessment of cyanotoxins. MCs are the most commonly found cyanobacterial toxins that cause a major challenge for the production of safe drinking water and pose a serious threat to global public health as well as fundamental ecological processes due to their potential carcinogenicity. Here, we emphasize recent updates on different modes of action of their possible carcinogenicity. Besides the harmful effects on human and animals, MC producing cyanobacteria can also present a harmful effect on growth and development of agriculturally important plants. Overall, this review emphasizes the current understanding of MCs with their occurrence, geographical distribution, accumulation in the aquatic as well as terrestrial ecosystems, biosynthesis, climate-driven changes in their synthesis, stability and current aspects on its degradation, analysis, mode of action and their ecotoxicological effects.

The cyanotoxin-microcystins: current overview

Advantages and challenges of Tween 80 surfactant-enhanced technologies for the remediation of soils contaminated with hydrophobic organic compounds

Poly(ε-caprolactone)nanocapsules as carrier systems for herbicides: physico-chemical characterization and genotoxicity evaluation.

Scientists are rushing to study the tiny plastic specks that are in marine animals — and in us. Scientists are rushing to study the tiny plastic specks that are in marine animals — and in us.

Microplastics are everywhere — but are they harmful?

The invention discloses a method for degrading triphenylmethane dye wastewater by the method of microwave induced catalysis. The microwave induced catalysis method is adopted, and nano NiO is taken as a catalyst to degrade triphenylmethane dyes in a microwave device. The dosage of the nano NiO is 0.4-1.0g/L, and the initial concentration of the triphenylmethane dyes is 30-100mg/L. A reaction solution is aerated for 30 minutes at first, put into the microwave device for reaction, and kept aerated in the course of the reaction. The method adopts a microwave induced catalysis system, and catalytic reaction is carried out without any light source, which overcomes the defects of low light utilization rate and low light quantum efficiency of the photocatalysis technology. The experimental device adopted by the method is simple and convenient to be operated, and the reaction can be carried out at normal temperature and normal pressure, thus achieving the effects of saving energy and lowering energy consumption. By adopting the method, typical triphenylmethane dyes which are difficult to be biodegraded can be effectively degraded, which causes no secondary pollution, and has high TOC removing efficiency, and the method is characterized by high speed and high efficiency.

Method for microwave induced catalytic degradation of triphenyl methane dye waste water

The sorption-desorption experiments of the herbicide mefenacet on five soils with different physicochemical properties were conducted using bath equilibrium methods, and the effects of soil organic matter and pH value on sorption of this herbicide were also investigated. The results showed that the sorption and desorption behaviors of mefenacet on soils could be well described by both the linear model and Freundlich model. Sorption distribution coefficients K(oc) for five tested soil are between 849.5 L x kg(-1) and 1 818.8 L x kg(-1), which shows that mefenacet can be well adsorbed on soils. It is found that the sorption coefficients, K(d), K(f), and K(f) (1/n) had good correlation with organic matter content (OM) in soils. It is obviously suggested that organic matter was the dominant factor affecting the sorption of mefenacet on soils. For the same soil, the sorption amount of mefenacet decreased with the increase of pH value. The desorption hysteresis of mefenacet was revealed in the single-cycle sorption and desorption experiments, which indicated a weak transferability of this herbicide in soils.

Sorption and desorption behavior of the herbicide mefenacet on soils

Background The incidence of nephrolithiasis is increasing rapidly worldwide. Calcium oxalate is the most common constituent, contributing to approximately 80% of all kidney stones. The gut microbiome, through its oxalate-degrading ability, may play a role in decreasing morbidity due to urinary calculus. Fecal microbiome transplantation (FMT) has been reported to be effective in restoring the gastrointestinal microbial community in different conditions. The transplantation of whole communities that have oxalate-degrading function may be a more effective strategy than the transplantation of isolated strains. Methods FMT was carried out in male guinea pigs and male Sprague–Dawley laboratory rats (SDRs). Fresh feces were collected from guinea pigs housed in metabolic cages. SDRs were divided into four groups: two groups received standard rat chow (SC) (groups SC and SC + FMT), and two groups were fed a 5% potassium oxalate diet (OD) (groups OD + phosphate-buffered saline (PBS) and OD + FMT). On day 14, groups OD + PBS, OD + FMT, and SC + FMT received either PBS or guinea pig feces by esophageal gavage. The composition of the microbiota of guinea pigs and SDRs was analyzed using a 16S rRNA gene sequencing approach. Biochemical analysis of urine samples from SDRs revealed the presence of calcium oxalate (CaOx) crystals, which were presumed to originate from kidney stones. Renal function was examined using real-time PCR analysis and immunohistochemical staining for renin, angiotensin-converting enzyme, and osteopontin (OPN) expression. Results FMT resulted in a gut microbiota that was a mixture of guinea pig and SDR bacteria. A microbial network involving Muribaculaceae, Lactobacillus, and Bifidobacterium was activated by FMT in group OD + FMT. As a result, urinary oxalate, calcium, uric acid, creatinine and urea in urine samples were reduced significantly. Similarly, significant reduction of uric acid and blood urea nitrogen to creatinine ratio in serum samples was observed (p < 0.05). Microscopic observations revealed a high CaOx crystal score (4+) in the kidneys of rats in group OD + PBS, whereas a lower score (2+) was observed in the rats in group OD + FMT. Up-regulation of OPN and down-regulation of renin were also associated with FMT. Conclusion A microbial network involving Muribaculaceae and other oxalate-degrading bacteria achieved by FMT was capable of reducing urinary oxalate excretion and CaOx crystal deposition in the kidney through increasing intestinal oxalate degradation. FMT may exert a renoprotective function in oxalate-related kidney stones.

/pdf/increased-abundance-of-bacteria-of-the-family-muribaculaceae-1l2cvwkr.pdf

Increased abundance of bacteria of the family Muribaculaceae achieved by fecal microbiome transplantation correlates with the inhibition of kidney calcium oxalate stone deposition in experimental rats

Zhenyu Liu

Papers

Method for microwave induced catalytic degradation of triphenyl methane dye waste water

Sorption and desorption behavior of the herbicide mefenacet on soils

Increased abundance of bacteria of the family Muribaculaceae achieved by fecal microbiome transplantation correlates with the inhibition of kidney calcium oxalate stone deposition in experimental rats