Harnessing photosynthetic microorganisms for enhanced bioremediation of microplastics:A comprehensive review

Mismanaged plastics,upon entering the environment,undergo degradation through physicochemical and/or biological processes.This process often results in the formation of microplastics(MPs),the most prevalent form of plastic debris(<1 mm).MPs pose severe threats to aquatic and terrestrial ecosystems,necessitating innovative strategies for effective remediation.Some photosynthetic microorganisms can degrade MPs but there lacks a comprehensive review.Here we examine the specific role of photoautotrophic microorganisms in water and soil environments for the biodegradation of plastics,focussing on their unique ability to grow persistently on diverse polymers under sunlight.Notably,these cells utilise light and CO_(2) to produce valuable compounds such as carbohydrates,lipids,and proteins,showcasing their multifaceted environmental benefits.We address key scientific questions surrounding the utilisation of photosynthetic microorganisms for MPs and nanoplastics(NPs)bioremediation,discussing potential engineering strategies for enhanced efficacy.Our review highlights the significance of alternative biomaterials and the exploration of strains expressing enzymes,such as polyethylene terephthalate(PET)hydrolases,in conjunction with microalgal and/or cyanobacterial metabolisms.Furthermore,we delve into the promising potential of photo-biocatalytic approaches,emphasising the coupling of plastic debris degradation with sunlight exposure.The integration of microalgal-bacterial consortia is explored for biotechnological applications against MPs and NPs pollution,showcasing the synergistic effects in wastewater treatment through the absorption of nitrogen,heavy metals,phosphorous,and carbon.In conclusion,this review provides a comprehensive overview of the current state of research on the use of photoautotrophic cells for plastic bioremediation.It underscores the need for continued investigation into the engineering of these microorganisms and the development of innovative approaches to tackle the global issue of plastic pollution in aquatic and terrestrial ecosystems.

Synthesis and Crystal Structure of 9-（4-Methoxylphenyl）-1,8-di-oxo-3,4,5,6,7,9-hexahydroxanthene under Microwave Irradiation

The crystal structure of the title compound (C20H20O4, Mr = 324.36) has been determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group Pbcn with a = 15.823(2), b = 18.002(3), c = 11.674(2) ?, V = 3325.34(67) ?3, Dc = 1.296 g/cm3, μ = 0.090 mm-1, Z = 8, F(000) = 1376, the final R = 0.0421 and wR = 0.0996. In the molecular structure, the pyran ring is of boat conformation, and the two six-membered rings fused with it adopt twisting-boat conformations.

Anti-oxidant and Anti-inflammatory Effects of Ethanol Extract from Polygala sibirica L.var megalopha Fr.on Lipopolysaccharide-Stimulated RAW264.7 Cells

Objective To investigate the anti-oxidant and anti-inflammatory effects of ethanol extract of Polygala sibirica L.var megalopha Fr.(EEP)on RAW264.7 mouse macrophages.Methods RAW264.7 cells were pretreated with 0–200µg/mL EEP or vehicle for 2 h prior to exposure to 1µg/mL lipopolysaccharide(LPS)for 24 h.Nitric oxide(NO)and prostaglandin(PGE2)production were determined by Griess reagent and enzyme-linked immunosorbent assay(ELISA),respectively.The mRNA levels of inducible nitric oxide synthase(iNOS),cyclooxygenase-2(COX-2),tumor necrosis factorα(TNF-α),interleukin-1beta(IL-1β),and IL-6 were determined using reverse transcription polymerase chain reaction(RT-PCR).Western blot assay was used to determine the protein expressions of iNOS,COX-2,phosphorylation of extracellular regulated protein kinases(ERK1/2),c-Jun N-terminal kinase(JNK),inhibitory subunit of nuclear factor Kappa B alpha(IκB-α)and p38.Immunofluorescence was used to observe the nuclear expression of nuclear factor-κB p65(NF-κB p65).Additionally,the anti-oxidant potential of EEP was evaluated by reactive oxygen species(ROS)production and the activities of catalase(CAT)and superoxide dismutase(SOD).The 2,2-diphenyl-1-picrylhydrazyl(DPPH),hydroxyl(OH),superoxide anion(O2−)radical and nitrite scavenging activity were also measured.Results The total polyphenol and flavonoid contents of EEP were 23.50±2.16 mg gallic acid equivalent/100 g and 43.78±3.81 mg rutin equivalent/100 g.With EEP treatment(100 and 150µg/mL),there was a notable decrease in NO and PGE2 production induced by LPS in RAW264.7 cells by downregulation of iNOS and COX-2 mRNA and protein expressions(P<0.01 or P<0.05).Furthermore,with EEP treatment(150µg/mL),there was a decrease in the mRNA expression levels of TNF-α,IL-1βand IL-6,as well as in the phosphorylation of ERK,JNK and p38 mitogen-activated protein kinase(MAPK,P<0.01 or P<0.05),by blocking the nuclear translocation of NF-κB p65 in LPS-stimulated cells.In addition,EEP(100 and 150µg/mL)led to an increase in the anti-oxidant enzymes activity of SOD and CAT,with a concomitant decrease in ROS production(P<0.01 or P<0.05).EEP also indicated the DPPH,OH,O2−radical and nitrite scavenging activity.Conclusion EEP inhibited inflammatory responses in activated macrophages through blocking MAPK/NF-κB pathway and protected against oxidative stress.

Community assemblage of free-living diazotrophs along the elevational gradient of Mount Gongga

Mountain systems are unique for studying the responses of species distribution and diversity to environmental changes along elevational gradients.It is well known that free-living diazotrophic microorganisms are important to nitrogen cycling in mountain systems.However,the elevational patterns of free-living diazotrophs and the underlying ecological processes in controlling their turnover along broader gradients are less well documented.Here,we investigated the pattern of diazotrophic diversity along the elevational gradient(1800 m-4100 m)in Mount Gongga of China.The results showed that the α-diversity of diazotrophs did not change with the elevation from 1800 m to 2800 m,but decreased at elevations above 3000 m.Such diversity pattern was driven mainly by soil total carbon,nitrogen,and plant richness.Various diazotrophic taxa showed differential abundance-elevation relationships.Ecological processes determining diazotrophic community assemblage shift along the elevations.Deterministic processes were relatively stronger at both low and high elevations,whereas stochastic processes were stronger at the middle elevation.This study also suggested a strong relationship among aboveground plants and diazotrophs,highlighting their potential interactions,even for free-living diazotrophs.

One-pot Synthesis of lO-Methyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-l,8-dione Derivatives under Microwave Heating without Catalyst

A series of 10-methyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione derivatives were synthesized by one-pot reaction of aldehyde, dimedone or 1,3-cyclohexanedione and methylamine in glycol or water under microwave heating without catalyst. The method has the advantage of short routine and reaction time, high yields as well as friendly environment. And the reaction was not only suitable for aliphatic and aromatic monoaldehyde, but also for aromatic dialdehyde.

A Simple One-pot Synthesis of 3,5-Dicyano-1,2-dihydropyrid-2-ones in Aqueous Media

A simple and clean synthesis of 3,5-dicyano-1,2-dihydropyrid-2-ones by a one-pot three-component reaction of malononitrile, aromatic aldehydes and 2-cyanoacetamide or 2-cyanothioacetamide has been achieved in an aqueous solution with potassium carbonate as a base under microwave irradiation without a phase transfer reagent. This protocol has the advantages of short reaction time （5-8 min） and convenient work-up.

Lyn prevents aberrant inflammatory responses to Pseudomonas infection in mammalian systems by repressing a SHIP-1-associated signaling cluster

The pleiotropic Src kinase Lyn has critical roles in host defense in alveolar macrophages against bacterial infection,but the underlying mechanism for Lyn-mediated inflammatory response remains largely elusive.Using mouse Pseudomonas aeruginosa infection models,we observed that Lyn^(−/−)mice manifest severe lung injury and enhanced inflammatory responses,compared with wild-type littermates.We demonstrate that Lyn exerts this immune function through interaction with IL-6 receptor and cytoskeletal protein Ezrin via its SH2 and SH3 domains.Depletion of Lyn results in excessive STAT3 activation,and enhanced the Src homology 2-containing inositol-5-phopsphatase 1(SHIP-1)expression.Deletion of SHIP-1 in Lyn^(−/−)mice(double knockout)promotes mouse survival and reduces inflammatory responses during P.aeruginosa infection,revealing the rescue of the deadly infectious phenotype in Lyn deficiency.Mechanistically,loss of SHIP-1 reduces NF-κB-dependent cytokine production and dampens MAP kinase activation through a TLR4-independent PI3K/Akt pathway.These findings reveal Lyn as a regulator for host immune response against P.aeruginosa infection through SHIP-1 and IL-6/STAT3 signaling pathway in alveolar macrophages.