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Biosynthesis of phospholipids is fundamental for membrane biogenesis in all living organisms. As a member of the Glycerol-3-phosphate (G3P) Acyltransferase (GPAT) family, PlsB is a crucial enzyme catalyzing the first step of phospholipid synthesis by converting G3P and fatty acyl-coenzyme A (CoA)/acyl-carrier protein (ACP) into lysophosphatidic acid and free CoA (CoASH)/ACP. In bacterial cells, PlsB participates in the formation of persister cells related to multidrug tolerance, and is hence considered as a potential target for anti-persister therapy. By using the single-particle cryo-electron microscopy (cryo-EM) method, we have solved the structure of full-length PlsB fromThemomonas haemolytica(ThPlsB) at 2.79 Å resolution. TheThPlsB protein forms a homodimer withC2 symmetry and each monomer contains three distinct domains, namely the amino-terminal domain (NTD), the middle catalytic domain (MCD) and the carboxy-terminal domain (CTD). For the first time, we have unraveled the binding sites of a fatty acyl-CoA and a 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) molecule in the MCD of PlsB. The interactions betweenThPlsB and the membrane involve two surface-exposed amphipathic regions located in the NTD and MCD respectively. The results of structural and biochemical analyses suggest a membrane surface association-catalysis coupling model for the PlsB-mediated biosynthesis of lysophosphatidic acid occurring at the membrane-cytosol interface.

In this study, two arrested anaerobic digestion bioreactors fed with food waste operated under different hydraulic retention times (HRTs) exhibited long-term stable volatile fatty acid (VFA) production performance including similar total yields (p= .085) with propionic acid (PA) being the most abundant VFA. Meta-omics analysis revealed distinct microbial structures (p= .02) at the two HRTs while there were no differences in potential and extant functionality as indicated by the whole-genome and whole-transcriptome sequencing, respectively. The highest potential (relative abundance of DNA sequence reads) and extant (relative abundance of mRNA sequence reads) functionality corresponded with PA production compared to other acids. The most abundant genusPrevotellaproduced PA mainly through the acryloyl-CoA pathway. Based on our results, the mechanistic basis for the similar VFA production performance observed under the HRTs tested lies in the community-level redundancy in convergent acidification functions and pathways, rather than trends in community structure.

SummaryChloroplasts rely on the translocon complexes in the outer and inner envelope membranes (termed TOC and TIC, respectively) to import thousands of different nuclear-encoded proteins from the cytosol1–4. While previous studies indicated that the TOC and TIC complexes may assemble into larger supercomplexes5–7, the overall architectures of the TOC-TIC supercomplexes and the mechanism of preprotein translocation are elusive. Here we report the cryo-electron microscopy (cryo-EM) structure of the TOC-TIC supercomplex fromChlamydomonas reinhardtiiat an overall resolution of 2.8 Å. The major subunits of the TOC complex (Toc75, Toc90 and Toc34) and TIC complex (Tic214, Tic20, Tic100 and Tic56), three chloroplast translocon-associated proteins (Ctap3, Ctap4 and Ctap5) and three newly-identified small inner-membrane proteins (Simp1-3) have been located in the supercomplex. As the largest protein, Tic214 traverses the inner membrane, the intermembrane space and the outer membrane, connecting the TOC complex with the TIC proteins. An inositol hexaphosphate (InsP6 or I6P) molecule is located at the Tic214-Toc90 interface and stabilizes their assembly. Moreover, four lipid molecules are located within or above an inner-membrane funnel formed by Tic214, Tic20, Simp1 and Ctap5. Furthermore, multiple potential pathways found in the TOC-TIC supercomplex may support translocation of different substrate preproteins into chloroplasts.

In green algae and plants, state transitions serve as a short-term light-acclimation process in the regulation of the light-harvesting capacity of photosystems I and II (PSI and PSII, respectively). During the process, a portion of light-harvesting complex II (LHCII) is phosphorylated, dissociated from PSII and binds with PSI to form the supercomplex PSI–LHCI–LHCII. Here, we report high-resolution structures of PSI–LHCI–LHCII from Chlamydomonas reinhardtii, revealing the mechanism of assembly between the PSI–LHCI complex and two phosphorylated LHCII trimers containing all four types of LhcbM protein. Two specific LhcbM isoforms, namely LhcbM1 and LhcbM5, directly interact with the PSI core through their phosphorylated amino terminal regions. Furthermore, biochemical and functional studies on mutant strains lacking either LhcbM1 or LhcbM5 indicate that only LhcbM5 is indispensable in supercomplex formation. The results unravel the specific interactions and potential excitation energy transfer routes between green algal PSI and two phosphorylated LHCIIs. High-resolution structures of the PSI–LHCI–LHCII supercomplex from Chlamydomonas reinhardtii reveal the mechanism of assembly between the PSI–LHCI complex and two phosphorylated LHCII trimers.

Nitrogen pollution is one of the main reasons for water eutrophication. The difficulty of nitrogen removal in low-carbon wastewater poses a huge potential threat to the ecological environment and human health. As a clean biological nitrogen removal process, solid-phase denitrification (SPD) was proposed for long-term operation of low-carbon wastewater. In this paper, the progress, hotspots, and challenges of the SPD process based on different solid carbon sources (SCSs) are reviewed. Compared with synthetic SCS and natural SCS, blended SCSs have more application potential and have achieved pilot-scale application. Differences in SCSs will lead to changes in the enrichment of hydrolytic microorganisms and hydrolytic genes, which indirectly affect denitrification performance. Moreover, the denitrification performance of the SPD process is also affected by the physical and chemical properties of SCSs, pH of wastewater, hydraulic retention time, filling ratio, and temperature. In addition, the strengthening of the SPD process is an inevitable trend. The strengthening measures including SCSs modification and coupled electrochemical technology are regarded as the current research hotspots. It is worth noting that the outbreak of the COVID-19 epidemic has led to the increase of disinfection by-products and antibiotics in wastewater, which makes the SPD process face challenges. Finally, this review proposes prospects to provide a theoretical basis for promoting the efficient application of the SPD process and coping with the challenge of the COVID-19 epidemic.

Trichloroacetic acid (TCA), a toxic substance produced in the disinfection process of wastewater treatment plants, will accumulate in the receiving water. The detection of TCA in the water can achieve the purpose of early warning. However, currently there are few reports on microbial sensors used for TCA detection, and the characteristics of their microbial communities are still unclear. In this work, a toxicity monitoring microbial system (TMMS) with nitrifying biofilm as a sensing element and cathode oxygen reduction as a current signal was successfully constructed for TCA detection. The current and nitrification rate showed a linear relationship with low TCA concentration from 0 to 50 μg/L (R

Biodiesel is an alternative fuel to addressing the energy shortage problem. Microbial lipids have attracted widespread attention as one of the potential feed-stocks for cost-effective and efficient biodiesel production. However, the large-scale production of microbial lipids is hampered by the complexity and the high cost of aseptic culturing approach. Metschnikowia pulcherrima is an oleaginous yeast with strong environmental adaptability. It is capable of utilizing a wide spectrum of substrates, and can be cultured under non-sterile conditions. Therefore, this yeast has great potential to replace the traditional oleaginous microorganisms, particularly in the area of recycling wastewater and solid waste for the production of biodiesel. Based on the analysis of lipid production and application conditions of M. pulcherrima, this review summarized the unique advantages of M. pulcherrima and the key factors affecting lipids production. We further discussed the feasibility of cultivating M. pulcherrima on various organic wastes under non-sterile conditions for lipids production. Moreover, we analyzed the challenges associated with M. pulcherrima's in the yield and mechanism for lipids production, and proposed perspectives for how to achieve efficient biodiesel production using this yeast.

Microalgal-bacterial granular sludge (MBGS) process has a gorgeous prospect for municipal wastewater treatment, but the research on the treatment of complex organic wastewater by MBGS process with CO

Due to the extremely low C/N ratio, high concentration of ammonia nitrogen and refractory organic matter of mature landfill leachate (MLL), appropriate processes should be selected to effectively remove nitrogen and reduce disposal costs. Partial nitritation (PN) and anaerobic ammonia oxidation (AMX) have been used as the main nitrogen removal processes for MLL, and the sludge granulation in PN and AMX processes could contribute to high biological activity, good sedimentation performance, and stable resistance to toxicity. In this study, the O

Green algae and plants rely on light-harvesting complex II (LHCII) to collect photon energy for oxygenic photosynthesis. In Chlamydomonas reinhardtii, LHCII molecules associate with photosystem II (PSII) to form various supercomplexes, including the C2S2M2L2 type, which is the largest PSII-LHCII supercomplex in algae and plants that is presently known. Here, we report high-resolution cryo-electron microscopy (cryo-EM) maps and structural models of the C2S2M2L2 and C2S2 supercomplexes from C. reinhardtii. The C2S2 supercomplex contains an LhcbM1-LhcbM2/7-LhcbM3 heterotrimer in the strongly associated LHCII, and the LhcbM1 subunit assembles with CP43 through two interfacial galactolipid molecules. The loosely and moderately associated LHCII trimers interact closely with the minor antenna complex CP29 to form an intricate subcomplex bound to CP47 in the C2S2M2L2 supercomplex. A notable direct pathway is established for energy transfer from the loosely associated LHCII to the PSII reaction centre, as well as several indirect routes. Structure-based computational analysis on the excitation energy transfer within the two supercomplexes provides detailed mechanistic insights into the light-harvesting process in green algae.

Global anthropogenic greenhouse gas emissions have exacerbated climate variation. Climate variation impacts the agricultural production and rural residents’ income negatively, further widening the urban-rural income gap and harming the co-benefits. Narrowing the income gap has always been a global concern and an important part of China’s rural revitalization strategy. However, little is known about whether digital inclusive finance can mitigate the negative impact of climate variation on rural residents’ income growth in China. Using panel data from 31 provinces in China from 2011 to 2019 and a digital inclusive finance index developed by Peking University, together with historical temperature data, this study examined the impact of digital inclusive finance on Chinese rural residents’ income growth in response to climate variation. It was found that digital inclusive finance could promote rural resident operating, wage, and transfer income growth. A heterogeneity analysis revealed that rural residents in central and western regions experienced larger digital inclusive finance facilitating effects on income growth than the eastern regions. Further analyses using the Spatial Dubin Model found that digital inclusive finance had a spatial spillover effect as it could significantly promote income growth in neighboring provinces. Although climate variation reduced rural residents’ income and increased their risks, digital inclusive finance significantly mitigated this negative effect. Digital information infrastructure construction, financial risk prevention, digital financial knowledge, and e-commerce popularization were practical paths to optimizing inclusive finance development in rural areas and promoting poverty alleviation and rural revitalization to resist climate risks.

In green algae and plants, state transitions serve as a short-term light-acclimation process in the regulation of the light-harvesting capacity of photosystems I and II (PSI and PSII, respectively). During the process, a portion of light-harvesting complex II (LHCII) is phosphorylated, dissociated from PSII and binds with PSI to form the supercomplex PSI-LHCI-LHCII. Here, we report high-resolution structures of PSI-LHCI-LHCII from Chlamydomonas reinhardtii, revealing the mechanism of assembly between the PSI-LHCI complex and two phosphorylated LHCII trimers containing all four types of LhcbM protein. Two specific LhcbM isoforms, namely LhcbM1 and LhcbM5, directly interact with the PSI core through their phosphorylated amino terminal regions. Furthermore, biochemical and functional studies on mutant strains lacking either LhcbM1 or LhcbM5 indicate that only LhcbM5 is indispensable in supercomplex formation. The results unravel the specific interactions and potential excitation energy transfer routes between green algal PSI and two phosphorylated LHCIIs.

Bioconversion of chitin-containing waste to N-acetyl-d-glucosamine (GlcNAc) is of economic interest. Highly efficient chitinases are thus desirable. Bacillus subtilis is a well-known microorganism for industrial protein production and biocontrol, however its chitinolytic enzyme has not been studied in detail. In this study, BsChi from B. subtilis was recombinantly expressed in Escherichia coli and characterized as a potent chitinase for degrading crystalline chitin substrates such as α-chitin, β-chitin and crab shells. BsChi was found to outperform the well-known SmChiA from Serratia marcescens and the commercial chitinase preparation from Streptomyces griseus in degrading crude crab shell which was pretreated by mechanical grinding and protease. In combination with OfHex1, a β-N-acetyl-d-hexosaminidase from the insect Ostrinia furnacalis, BsChi could produce 1.63 g of GlcNAc with 95% purity from 10 g of pretreated crab shells with a yield of 60%.

Peripheral vascular disease (PVD) is a prevalent vascular disease that affect a large number of patients. The establishment of optimal treatments to mitigate the intimal hyperplasia (IH)-induced restenosis would help relieve the health burden of the PVD. Ribonucleotide reductase M2 (RRM2) is critical to cellular migration and proliferation. We have previously demonstrated that suppression of RRM2 expression could substantially inhibit hepatocellular carcinoma cell proliferation and migration. We hereby developed RRM2 small interfering RNA (siRNA)-loaded cell penetrating peptides-conjugated liposome-polycation-DNA complex (LPD) (RRM2-CLPD), aiming to inhibit the migration and proliferation of vascular smooth muscle cells (VSMCs) crucial for IH. RRM2-CLPD is of a small size (∼150 nm) and high siRNA encapsulation efficiency (∼90%). Further, we demonstrated that RRM2-CLPD could significantly inhibited RRM2 gene and protein expression by ∼80%. Notably, RRM2-CLPD was able to effectively bind to VSMCs, resulting in significant cellular proliferation and migration inhibition. Taken together, RRM2-CLPD represent a very promising treatment for IH.

Wastewater containing chemical energy and water resources is supposed to be efficiently recovered and utilized. However, conventional wastewater treatment, which is energy intensive and costly, focuses on the degradation of pollutants but ignores the reuse of resources. This study explored the feasibility of integrating wastewater treatment with biofuel production by oleaginous yeasts Rhodosporidium toruloides for sustainability concerns. Aerobic fermentation of R. toruloides was used to treat synthetic sugar-containing wastewater (SSCW) and synthetic sugar-containing wastewater anaerobic fermentation broth (SSCW-AFB). Flux balance analysis (FBA) was used to explore the optimal metabolic flux distributions for lipid production, and the potential of R. toruloides to utilize acetic acid was studied through metabolic network analysis for the first time. Sequencing batch cultivation was used to enhance nutrient removal and microbial lipid accumulation, achieving 87.0 ± 2.4% and 61.0 ± 0.1% total organic carbon (TOC) removal coupled with 30.6 ± 1.1% and 73.5 ± 0.7% lipid content in SSCW and SSCW-AFB, respectively. The in silico results revealed that nicotinamide adenine dinucleotide phosphate (NADPH)-producing flux of R. toruloides grown on acetic acid preferred going through malic enzyme related pathways rather than the pentose phosphate pathway, resulting in less 15.6% CO2 emissions which in turn facilitates the lipid accumulation. Consistent with the model predictions, a higher lipid coefficient (147.0 mg/g acetic acid) was achieved in SSCW-AFB compared with that in SSCW (105.3 mg/g glucose) during the bioprocess. Furthermore, the lipid production performance under a low seed cell density (0.4 g/L) was significantly better than that under a high seed cell density (4 g/L). Analysis of the biofuel properties indicated the suitability of using SSCW and SSCW-AFB as feedstocks for the industrial production of biodiesel. The results of this study provide valuable information for promoting resource and energy recovery and reducing carbon emission during the wastewater biological treatment process by oleaginous microorganisms.

Metschnikowia pulcherrima, a non-traditional oleaginous yeast, was investigated using 0.5–20 g/L of acetic, propionic, butyric and valeric acid (four model products of anaerobic acidification) respectively as carbon sources to accumulate microbial lipids so as to produce biodiesel. The results showed that acetic acid was the most efficient carbon source for improving cell growth, lipid content and biodiesel quality. After 8 cycles non-sterile batch cultivation, M. pulcherrima still dominated in bioreactor. Controlling C/P ratio, K+ and Na+ concentrations, and initial pH could effectively enhance the lipid content to 25.79 ± 0.51%. Under nitrogen starvation, M. pulcherrima performed higher cellular activity and lipid productivity than that of phosphorous limitation. The biomass yield was about twice and the lipid content was 3% higher. Besides, different from the lipid improvement strategy of traditional oleaginous yeast, acetate from ethanol served as the precursor of M. pulcherrima cytoplasmic acetyl-CoA instead of citric acid, and pentose phosphate pathway (PPP) was the main donor of reducing equivalent NADPH by transcriptomics sequencing analysis. These results demonstrate M. pulcherrima is a promising species for large-scale production of biofuel from organic wastes due to the low operating and maintenance costs of non-sterile cultivation, which is beneficial for reducing environmental pollution and energy shortages.

Green algae and plants rely on light-harvesting complex II (LHCII) to collect photon energy for oxygenic photosynthesis. In Chlamydomonas reinhardtii, LHCII molecules associate with photosystem II (PSII) to form various supercomplexes, including the C

Soluble microbial products (SMPs) can act as a disinfection byproduct (DBP) precursor besides natural organic matter (NOM) when source water is polluted by biologically treated wastewater effluent that has SMPs as its main component. Influential factors of SMPs as a DBP precursor were investigated in this study. Model feed substrates were biologically incubated to simulate the biological treatment of wastewater organics, and the SMPs produced were chlorinated according to the standard procedure to study the DBP formation potential (DBPFP) of SMPs. Feed chemical type is a crucial factor affecting SMP production and the following DBP formation. SMPs from four kinds of model feed substrates with the same initial organic carbon concentration produced DBPs with a wide range from 196 to 684 μg L−1 and also different DBP formation properties. Different organic substrates would facilitate the growth of different microbial species, which produce SMPs with varied levels and chemical structure and subsequently different DBP formation characters. For the environmental factors, an anaerobic condition showed a significant effect, producing extremely high chloral hydrate up to about 2000 μg L−1, probably due to the production of volatile fatty acids. Different incubation conditions can not only bring about different levels of SMPs and DBPs, but also SMPs with different DBP formation feathers.

To evaluate the incidence of postoperative venous thromboembolism after gynecologic surgery by mode of incision.We conducted a retrospective cohort study of all patients who underwent gynecologic surgery from May 2006 to June 2015 at two tertiary care academic hospitals in Massachusetts. Billing and diagnosis codes were used to identify surgeries and cases of venous thromboembolism.A total of 43,751 surgical encounters among 37,485 individual patients were noted during the study. The overall incidence of venous thromboembolism is 0.2% for all gynecologic surgeries, 0.7% for hysterectomy, and 0.2% for myomectomy. Compared with patients undergoing laparotomy, patients who underwent minimally invasive gynecologic surgery were less likely to develop venous thromboembolism (laparoscopy risk ratio 0.22, 95% CI 0.13-0.37; vaginal surgery risk ratio 0.07, 95% CI 0.04-0.12). This effect persisted when data were adjusted for other known venous thromboembolism risk factors such as age, race, cancer, medical comorbidities, use of pharmacologic thromboprophylaxis, admission status, and surgical time.Minimally invasive surgery is associated with a decreased risk of venous thromboembolism in patients undergoing gynecologic surgery, including hysterectomy and myomectomy. Although society guidelines and risk assessment tools do not currently account for mode of surgery when assessing venous thromboembolism risk and recommendations for prevention, there is a small but growing body of evidence in both general and gynecologic surgery literature that surgical approach affects a patient's risk of postoperative venous thromboembolism. Mode of surgery should be considered when assessing venous thromboembolism risk and planning venous thromboembolism prophylaxis for patients undergoing gynecologic surgery.

Objectives: To explore the implications of cervical conization specimens lacking the targeted high-grade squamous intraepithelial lesions (negative cone). Methods: We studied 540 conization procedures: 400 positive cones and 140 negative cones. Clinicopathologic features and 2-year follow-up results were reported. Results: Negative cones comprised 22% of procedures triggered by CIN2 or higher biopsies. Procedures triggered by cytology produced much higher percentages of negative cones (37% high-grade squamous intraepithelial lesion [HSIL], 46% atypical squamous cells—cannot exclude high-grade squamous intraepithelial lesion [ASC-H], and 76% low-grade squamous intraepithelial lesion—cannot exclude high-grade squamous intraepithelial lesion [LSIL-H]). Upon reviewing negative excision-triggering biopsy and cytology, we downgraded 24 (24%) CIN2 biopsies, three (14%) HSIL, five (83%) ASC-H, and 12 (92%) LSIL-H. One-third of our negative cones can be attributed to overdiagnosis either on biopsy or cytology. Patients with negative cones were older and had smaller excisions, negative colposcopic findings, and negative/equivocal high-risk human papillomavirus (HR-HPV). Within 2 years, 35 (25%) women with negative cones experienced ASCUS or LSIL. Only one (0.7%) recurred as CIN3, a significantly lower percentage than women with positive cones (13%). Conclusions: We advocate careful review of all excision-triggering biopsy and cytology, especially in cases of LSIL-H. Patients with negative cones should be surveyed with cytology and HR-HPV testing.