Continuous selenite biotransformation and biofuel production by marine diatom in the presence of fulvic acid.

In this study, the biochemical response of Phaeodactylum tricornutum to varying concentrations of inorganic selenium (Se) was investigated. It was observed that, when combined with fulvic acid, P. tricornutum exhibited enhanced uptake and biotransformation of inorganic Se, as well as increased microalgal lipid biosynthesis. Notably, when subjected to moderate (5 and 10 mg/L) and high (20 and 40 mg/L) concentrations of selenite under fulvic acid treatment, there was a discernible redirection of carbon flux towards lipogenesis and protein biosynthesis from carbohydrates. In addition, the key parameters of microalgae-based biofuels aligned with the necessary criteria outlined in biofuel regulations. Furthermore, the Se removal capabilities of P. tricornutum, assisted by fulvic acid, were coupled with the accumulation of substantial amounts of organic Se, specifically SeCys. These findings present a viable and successful approach to establish a microalgae-based system for Se uptake and biotransformation.

Exposure to microplastics renders immunity of the thick-shell mussel more vulnerable to diarrhetic shellfish toxin-producing harmful algae.

Despite both microplastics (MPs) and harmful algae blooms (HABs) may pose a severe threat to the immunity of marine bivalves, the toxification mechanism underlying is far from being fully understood. In addition, owing to the prevalence and sudden occurrence characteristics of MPs and HABs, respectively, bivalves with MP-exposure experience may face acute challenge of harmful algae under realistic scenarios. However, little is known about the impacts and underlying mechanisms of MP-exposure experience on the susceptibility of immunity to HABs in bivalve mollusks. Taking polystyrene MPs and diarrhetic shellfish toxin-producing Prorocentrum lima as representatives, the impacts of MP-exposure on immunity vulnerability to HABs were investigated in the thick-shell mussel, Mytilus coruscus. Our results revealed evident immunotoxicity of MPs and P. lima to the mussel, as evidenced by significantly impaired total count, phagocytic activity, and cell viability of haemocytes, which may result from the induction of oxidative stress, aggravation of haemocyte apoptosis, and shortage in cellular energy supply. Moreover, marked disruptions of immunity, antioxidant system, apoptosis regulation, and metabolism upon MPs and P. lima exposure were illustrated by gene expression and comparative metabolomic analyses. Furthermore, the mussels that experienced MP-exposure were shown to be more vulnerable to P. lima, indicated by greater degree of deleterious effects on abovementioned parameters detected. In general, our findings emphasize the threat of MPs and HABs to bivalve species, which deserves close attention and more investigation.

Mechanistic insights into the effects of diuron exposure on Alexandrium pacificum.

Diuron (N-(3,4-dichlorophenyl)-N,N­dimethylurea, DCMU), a ureic herbicide, is extensively used in agriculture to boost crop productivity; however, its extensive application culminates in notable environmental pollution, especially in aquatic habitats. Therefore, the present study investigated the effect of diuron on the dinoflagellate Alexandrium pacificum, which is known to induce harmful algal blooms (HAB), and its potential to biodegrade DCMU. Following a four-day DCMU exposure, our results revealed that A. pacificum proficiently assimilated DCMU at concentrations of 0.05 mg/L and 0.1 mg/L in seawater, attaining a complete reduction (100 % efficiency) after 96 h for both concentrations. Moreover, evaluations of paralytic shellfish toxins content indicated that cells subjected to higher DCMU concentrations (0.1 mg/L) exhibited reductions of 73.4 %, 86.7 %, and 75 % in GTX1, GTX4, and NEO, respectively. Exposure to DCMU led to a notable decrease in A. pacificum's photosynthetic efficacy, accompanied by increased levels of reactive oxygen species (ROS) and suppressed cell growth, with a growth inhibition rate of 41.1 % at 72 h. Proteomic investigations pinpointed the diminished expression levels of specific proteins like SxtV and SxtW, linked to paralytic shellfish toxins (PSTs) synthesis, as well as key proteins associated with Photosystem II, namely PsbA, PsbD, PsbO, and PsbU. Conversely, proteins central to the cysteine biosynthesis pathways exhibited enhanced expression. In summary, our results preliminarily resolved the molecular mechanisms underlying the response of A. pacificum to DCMU and revealed that DCMU affected the synthesis of PSTs. Meanwhile, our data suggested that A. pacificum has great potential in scavenging DCMU.

Systematic dissection of genomic features determining the vast diversity of conotoxins.

BACKGROUND: Conus, a highly diverse species of venomous predators, has attracted significant attention in neuroscience and new drug development due to their rich collection of neuroactive peptides called conotoxins. Recent advancements in transcriptome, proteome, and genome analyses have facilitated the identification of conotoxins within Conus' venom glands, providing insights into the genetic features and evolutionary patterns of conotoxin genes. However, the underlying mechanism behind the extraordinary hypervariability of conotoxins remains largely unknown. RESULTS: We analyzed the transcriptomes of 34 Conus species, examining various tissues such as the venom duct, venom bulb, and salivary gland, leading to the identification of conotoxin genes. Genetic variation analysis revealed that a subset of these genes (15.78% of the total) in Conus species underwent positive selection (Ka/Ks > 1, p < 0.01). Additionally, we reassembled and annotated the genome of C. betulinus, uncovering 221 conotoxin-encoding genes. These genes primarily consisted of three exons, with a significant portion showing high transcriptional activity in the venom ducts. Importantly, the flanking regions and adjacent introns of conotoxin genes exhibited a higher prevalence of transposon elements, suggesting their potential contribution to the extensive variability observed in conotoxins. Furthermore, we detected genome duplication in C. betulinus, which likely contributed to the expansion of conotoxin gene numbers. Interestingly, our study also provided evidence of introgression among Conus species, indicating that interspecies hybridization may have played a role in shaping the evolution of diverse conotoxin genes. CONCLUSIONS: This study highlights the impact of adaptive evolution and introgressive hybridization on the genetic diversity of conotoxin genes and the evolution of Conus. We also propose a hypothesis suggesting that transposable elements might significantly contribute to the remarkable diversity observed in conotoxins. These findings not only enhance our understanding of peptide genetic diversity but also present a novel approach for peptide bioengineering.

Utilization of lipidic food waste as low-cost nutrients for enhancing the potentiality of biofuel production from engineered diatom under temperature variations.

The scarcity of natural fossil fuels presents a promising opportunity for the development of renewable microalgae-based biofuels. However, the current microalgae cultivation is unable to effectively address the high costs of the production of biofuels. To tackle this challenge, this study focused on recruiting engineered Phaeodactylum tricornutum (FabG-OE) to enhance biomass accumulation and lipid production by employing food waste hydrolysate under temperature variations. The biomass and lipid accumulations of FabG-OE were improved effectively in mixed culture medium and food waste hydrolysate at a volume ratio (v/v) of 80:20 at 30 °C. It was found that oxidative stress might contribute to the overexpression of lipogenic genes, thereby leading to lipogenesis at 30 °C. Upscaling cultivation of FabG-OE at 30 °C using a semi-continuous strategy and batch strategy was conducted to achieve 0.73 and 0.77 g/L/d of biomass containing 0.35 and 0.38 g/L/d of lipid, respectively. In summary, these findings provide valuable insights for advancing microalgae-based biofuel production.

Toxicity and potential underlying mechanism of Karenia selliformis to the fish Oryzias melastigma.

Karenia selliformis can produce toxins such as gymnodimines, and form microalgal blooms causing massive mortality of marine life such as fish and shellfish, and resulting in serious economic losses. However, there are a few of studies on the toxic effects of K. selliformis on marine organisms and the underlying mechanisms, and it is not clear whether the toxins produced by K. selliformis affect fish survival through the food chain. In this study, a food chain was simulated and composed by K. selliformis-brine shrimp-marine medaka to investigate the possibility of K. selliformis toxicity transmission through the food chain, in which fish behavior, histopathology and transcriptomics changes were observed after direct or indirect exposure (through the food chain) of K. selliformis. We found that both direct and indirect exposure of K. selliformis could affect the swimming behavior of medaka, manifested as decreased swimming performance and increased "frozen events". Meanwhile, exposure to K. selliformis caused pathological damage to the intestine and liver tissues of medaka to different degree. The effect of direct exposure to K. selliformis on swimming behavior and damage to fish tissues was more severe. In addition, K. selliformis exposure induced significant changes in the expression of genes related to energy metabolism, metabolic detoxification and immune system in medaka. These results suggest that toxins produced by K. selliformis can be transferred through the food chain, and that K. selliformis can destroy the intestinal integrity of medaka and increase the absorption of toxins, leading to energy metabolism disorders in fish, affecting the metabolic detoxification capacity of the liver. Our finding provides novel insight into the toxicity of K. selliformis to marine fish.

Exposure to okadaic acid could disrupt the colonic microenvironment in rats.

Okadaic acid (OA) is one of the most prevalent marine phycotoxin with complex toxicity, which can lead to toxic symptoms such as diarrhea, vomiting, nausea, abdominal pain, and gastrointestinal discomfort. Studies have shown that the main affected tissue of OA is digestive tract. However, its toxic mechanism is not yet fully understood. In this study, we investigated the changes that occurred in the epithelial microenvironment following OA exposure, including the epithelial barrier and gut bacteria. We found that impaired epithelial cell junctions, mucus layer destruction, cytoskeletal remodeling, and increased bacterial invasion occurred in colon of rats after OA exposure. At the same time, the gut bacteria decreased in the abundance of beneficial bacteria and increased in the abundance of pathogenic bacteria, and there was a significant negative correlation between the abundance of pathogenic bacteria represented by Escherichia/Shigella and animal body weight. Metagenomic analysis inferred that Escherichia coli and Shigella spp. in Escherichia/Shigella may be involved in the process of cytoskeletal remodeling and mucosal layer damage caused by OA. Although more evidence is needed, our results suggest that opportunistic pathogens may be involved in the complex toxicity of OA during OA-induced epithelial barrier damage.

Systematic exploration of transcriptional responses of interspecies interaction between Karenia mikimotoi and Prorocentrum shikokuense.

Karenia mikimotoi and Prorocentrum shikokuense (also identified as P. donghaiense Lu and P. obtusidens Schiller) are two important harmful algal species which often form blooms in the coasts of China. Studies have shown that the allelopathy of K. mikimotoi and P. shikokuense plays an important role in inter-algal competition, though the underlying mechanisms remain largely unclear. Here, we observed reciprocal inhibitory effects between K. mikimotoi and P. shikokuense under co-cultures. Based on the reference sequences, we isolated RNA sequencing reads of K. mikimotoi and P. shikokuense from co-culture metatranscriptome, respectively. We found the genes involved in photosynthesis, carbon fixation, energy metabolism, nutrients absorption and assimilation were significantly up-regulated in K. mikimotoi after co-cultured with P. shikokuense. However, genes involved in DNA replication and cell cycle were significantly down-regulated. These results suggested that co-culture with P. shikokuense stimulated cell metabolism and nutrients competition activity of K. mikimotoi, and inhibited cell cycle. In contrast, genes involved in energy metabolism, cell cycle and nutrients uptake and assimilation were dramatically down-regulated in P. shikokuense under co-culture with K. mikimotoi, indicating that K. mikimotoi could highly affect the cellular activity of P. shikokuense. In addition, the expression of PLA2G12 (Group XII secretory phospholipase A2) that can catalyze the accumulation of linoleic acid or linolenic acid, and nitrate reductase that may be involved in nitric oxide production were significantly increased in K. mikimotoi, suggesting that PLA2G12 and nitrate reductase may play important roles in the allelopathy of K. mikimotoi. Our findings shed new light on the interspecies competition between K. mikimotoi and P. shikokuense, and provide a novel strategy for studying interspecific competition in complex systems.

Colloidal gold and fluorescent immunochromatographic test strips for canine parvovirus detection.

Canine parvovirus (CPV) is an acute and highly infectious virus causing disease in puppies and, thus, affecting the global dog industry. The current CPV detection methods are limited by their sensitivity and specificity. Hence, the current study sought to develop a rapid, sensitive, simple, and accurate immunochromatographic (ICS) test to detect and control the spread and prevalence of CPV infection. More specifically, 6A8, a monoclonal antibody (mAb) with high specificity and sensitivity, was obtained by preliminary screening. The 6A8 antibody was labelled with colloidal gold particles. Subsequently, 6A8 and goat anti-mouse antibodies were coated onto a nitrocellulose membrane (NC) as the test and control lines, respectively. Furthermore, 6A8 and rabbit IgG antibodies were labelled with fluorescent microspheres and evenly sprayed onto a glass fibre membrane. Both strips could be prepared in 15 min with no noticeable cross-reactivity with other common canine intestinal pathogens. The strips were simultaneously used to detect CPV in 60 clinical samples using real-time quantitative PCR, hemagglutination, and hemagglutination inhibition assays. The colloidal gold (fluorescent) ICS test strip was stable for 6 (7) and 4 (5) months at 4 °C and room temperature (18-25 °C). Both test strips were easy to prepare and rapidly detected CPV with high sensitivity and specificity. Moreover, the results were easily interpretable. This study establishes a simple method for two CPV diseases, colloidal gold and fluorescent immunochromatographic (ICS) test strips. KEY POINTS: • CPV test strips do not exhibit cross-reactivity with other canine intestinal pathogens. • The strips are stable for months at 4 °C and at room temperature (18-25 °C). • These strips are a promising approach for the timely diagnosis and treatment of CPV.

Bioremediation of Catechol and Concurrent Accumulation of Biocompounds by the Microalga Crypthecodinium cohnii.

Burgeoning commercial applications of catechol have led to its excessive accumulation in the environment, thereby posing a severe ecological threat. Bioremediation has emerged as a promising solution. The potential of the microalga Crypthecodinium cohnii to degrade catechol and use the byproduct as a carbon source was investigated in this study. Catechol significantly increased C. cohnii growth and was rapidly catabolized within 60 h of cultivation. Transcriptomic analysis highlighted the key genes involved in catechol degradation. Real-time polymerase chain reaction (RT-PCR) analysis showed that transcription of key genes CatA, CatB, and SaID involved in the ortho-cleavage pathway was remarkably increased by 2.9-, 4.2-, and 2.4- fold, respectively. Key primary metabolite content was also markedly altered, with a specific increment in polyunsaturated fatty acids. Electron microscopy and antioxidant analysis showed that C. cohnii could tolerate catechol treatment without morphological aberrations or oxidative stress. The findings provide a strategy for C. cohnii in the bioremediation of catechol and concurrent polyunsaturated fatty acids (PUFA) accumulation.

Possible Role of Docosahexaenoic Acid in Response to Diarrhetic Shellfish Toxins in the Mussel Perna viridis.

Marine bivalves are rich in docosahexaenoic acid (DHA), a polyunsaturated fatty acid known to be beneficial for human health; however, the potential role of DHA in protecting shellfish from the toxicity of diarrhetic shellfish toxins (DSTs) remains poorly understood. Here, we aimed to study the effect of DHA on the response of the bivalve, Perna viridis, to DSTs by using LC-MS/MS, RT-qPCR, and histological examination. In this study, we observed that the DHA content decreased significantly with esterification of DSTs in the digestive gland of the mussel P. viridis after 96 h of exposure to Prorocentrum lima, a DST-producing dinoflagellate. The addition of DHA significantly increased the esterification level of DSTs and increased the expression of Nrf2 signaling pathway-related genes and enzyme activities, alleviating the damage of DSTs to digestive glands. These results suggested that DHA may mediate the esterification of DSTs and activation of the Nrf2 signaling pathway in P. viridis to protect mussels from the toxic effects of DSTs. This study may provide new insights regarding the response of bivalves to DSTs and lay the foundation for uncovering the role of DHA in environmental adaptation of bivalves.

Microcystin-LR exposure interfered maintenance of colonic microenvironmental homeostasis in rat.

Microcystin-leucine arginine (MCLR) is a phycotoxin produced by cyanobacteria. As a hepatotoxin, increasing evidence suggests that it has some negative effects on the mammal gastrointestinal tract, but further studies are warranted. In this study, we investigated the effects of MCLR on the intestinal epithelial microenvironment by oral administration of MCLR. As expected, MCLR at doses of 200 and 400 µg kg-1 bw showed hepatorenal toxicity in rats but without significant gastrointestinal symptoms. MCLR exposure decreased the thickness of the colonic epithelial mucus layer, and down-regulated the expression of main mucin protein (MUC2), cytoskeletal assembly-related genes (Arpc1a, Enah) and cytoskeletal stability-related genes (Ptk2, Prkca, Actn1, Pxn, Tln1, Cttn, Vcl) in colonic tissue to varying degrees, but did not affect the expression of cell connection-related genes including Zo1, Ocln, Cldn2 and Cdh1. In addition, MCLR exposure had a limited effect on gut bacterial diversity but clearly enriched specific bacteria. Prevotella, which plays a crucial role in balancing health and disease, was inhibited, whereas Muribaculaceae concerning the epithelial barrier, was promoted. Together, our findings demonstrate that MCLR exposure can weaken the colonic epithelial barrier by interfering with the stability of the cytoskeleton, which in turn exacerbates the homeostasis maintenance in the intestinal microenvironment.

Responses of ABCB and ABCC transporters to the toxic dinoflagellate Prorocentrum lima in the mussel Perna viridis.

Bivalve mollusks can accumulate diarrheic shellfish poisoning (DSP) toxins through filter-feeding, but they exhibit some resistance to the toxins. Previous studies have suggested that the ABC transporters may have an important role in the resistance to DSP toxins, but comprehensive studies are lacking. In this study, we comprehensively analyzed the distribution of ABC transporters in the mussel Perna viridis, and observed responses of ABCB and ABCC transporters to the DSP toxins-producing dinoflagellate Prorocentrum lima. Total 39 members of ABC transporters were identified in P. viridis, including 3 full PvABCBs, 3 half PvABCBs, and 7 PvABCCs transporters. We found that PvABCBs and PvABCCs subfamilies were expressed in hemocytes, gills and digestive gland with some difference, especially in hemocytes. After exposure to P. lima, PvABCBs and PvABCCs displayed different expression changes in different tissues. The short-term (3 h) exposure to P. lima induced the transcription of PvABCB1_like1, PvABCB6, PvABCC1, PvABCC1_like and PvABCC1/3, and the longer-term (96 h) exposure increased the transcription of PvABCB1, PvABCB1_like, PvABCB10, PvABCC1 and PvABCC1_like1 in gills and PvABCC10 in digestive gland. These results suggest that different types of PvABCBs and PvABCCs in P. viridis may contribute to the detoxification of DSP toxins in different tissues at different time after exposure to DSP toxins. Our finding provides new evidence for further understanding the role of ABC transporters in the tolerance of mussel to DSP toxins.

Toxicity and underlying mechanism of the toxic dinoflagellate Gambierdiscus caribaeus to the fish Oryzias melastigma.

Gambierdiscus spp. is mainly responsible for the ciguatera fish poisoning (CFP) around the world. The gambiertoxin produced by Gambierdiscus can be passed through the food chain to form ciguatoxins (CTXs) that cause ciguatoxins poisoning. However, the toxic effects of Gambierdiscus on fish through the food chain and related mechanism remains unclear. In this study, the toxicity of Gambierdiscus caribaeus on the marine medaka (Oryzias melastigma) was investigated, where the simulated food chain toxic algae-food organism-fish (G. caribaeus-Artemia metanauplii-O. melastigma) was set. The results showed that direct or indirect exposure through the food chain of G. caribaeus could affect the swimming behaviour of O. melastigma, manifested as decreased swimming performance and spontaneous abnormal swimming behaviours. Histological observation showed that direct or indirect exposure of G. caribaeus caused different degrees of pathological damage to the gills, intestine and liver tissues of O. melastigma. Transcriptome sequencing and RT-qPCR demonstrated that G. caribaeus exposure could trigger a series of physiological and biochemical responses, mainly reflected in energy metabolism, reproductive system, neural activity, immune stress and drug metabolism in marine medaka. Our finding may provide novel insight into the toxicity of Gambierdiscus on fish.

The first evidence of shaking mink syndrome-astrovirus associated encephalitis in farmed minks, China.

A novel neurological disorder, shaking mink syndrome (SMS), emerged in Denmark and Sweden in 2000. SMS has seldom been reported in China, but the causative agent has not been detected in the country. SMS outbreaks occurred in multiple provinces in 2020. A total of 44 brain samples from minks associated with SMS were collected from Heilongjiang, Liaoning and Shandong provinces of which 28 samples (63.3%) were SMS-astrovirus (SMS-AstV)-positive by reverse transcription PCR. Histopathological examination revealed non-suppurative encephalitis in three minks. Moreover, the complete coding region sequences (CDSs, 6559 bp) of a sample collected from a 2-month-old mink (termed SMS-AstV-H1, GSA accession No. SAMC816786) were amplified by PCR and Sanger sequencing. The complete CDS and open reading frame 2 sequences of SMS-AstV-H1 were 94.3% and 96.4% identical to an SMS-AstV strain (GenBank accession number: GU985458). Phylogenetically, SMS-AstV-H1 was closely related to an SMS-AstV strain (GU985458). Based on the above results, we describe SMS-AstV-associated encephalitis in farmed minks in China. Future studies need to focus on epidemiology, virus isolation and potential interspecies transmission of SMS-AstV.

Toxic Responses of Different Shellfish Species after Exposure to Prorocentrum lima, a DSP Toxins Producing Dinoflagellate.

Prorocentrum lima is a global benthic dinoflagellate that produces diarrhetic shellfish poisoning (DSP) toxins, which can be ingested by filter-feeding bivalves, and eventually pose a great threat to human health through food chain. After being exposed to P. lima, different bivalves may accumulate various levels of DSP toxins and display different toxic responses. However, the underlying mechanism remains unclear. Here, we found that the content of okadaic acid-equivalents (OA-eq) varied in the digestive glands of the three bivalves including Crassostrea gigas, Mytilus coruscus and Tegillarca granosa after P. lima exposure. The degree of esterification of OA-eq in the three bivalves were opposite to the accumulation of OA-eq. The digestive gland tissues of the three bivalve species were damaged to different degrees. The transcriptional induction of Nrf2 targeted genes such as ABCB1 and GPx indicates the functionality of Nrf2 pathway against DSP toxins in bivalves. The oyster could protect against DSP toxins mainly through ABC transporters and esterification, while the mussel and clam reduce the damage induced by DSP toxins mainly by regulating the expression of antioxidant genes. Our findings may provide some explanations for the difference in toxic response to DSP toxins in different shellfish.

Supplementation with rac-GR24 Facilitates the Accumulation of Biomass and Astaxanthin in Two Successive Stages of Haematococcus pluvialis Cultivation.

The unicellular freshwater green alga Haematococcus pluvialis has attracted much research attention due to its biosynthetic ability for large amounts of astaxanthin, a blood-red ketocarotenoid that is used in cosmetics, nutraceuticals, and pharmaceuticals. Recently, numerous studies have investigated the functions of natural astaxanthin; however, the high cost of the production of astaxanthin from H. pluvialis cultures restricts its commercial viability. There is an urgent need to fulfill commercial demands by increasing astaxanthin accumulation from H. pluvialis cultures. In this study, we discovered that treatment of H. pluvialis cultures at the beginning of the macrozooid stage (day 0) with 1 µM rac-GR24, a synthetic analogue of strigolactones (a class of phytohormones), led to significant increases in biomass [up to a maximum dry cell weight (DCW) of 0.53 g/L] during the macrozooid stage and astaxanthin (from 0.63 to 5.32% of DCW) during the hematocyst stage. We elucidated that this enhancement of biomass accumulation during the macrozooid stage by rac-GR24 is due to its increasing CO2 utilization efficiency in photosynthesis and carbohydrate biosynthesis. We also found that rac-GR24 stimulated the overproduction of nicotinamide adenine dinucleotide phosphate (NADPH) and antioxidant enzymes in H. pluvialis cultures, which alleviated the oxidative damage caused by reactive oxygen species generated during the hematocyst stage due to the exhaustion of nitrogen supplies. Moreover, rac-GR24 treatment of H. pluvialis synergistically altered the activity of the pathways of fatty acid biosynthesis and astaxanthin esterification, which resulted in larger amounts of astaxanthin being generated by rac-GR24-treated cultures than by controls. In summary, we have developed a feasible and economic rac-GR24-assisted strategy that increases the amounts of biomass and astaxanthin generated by H. pluvialis cultures, and have provided novel insights into the mechanistic roles of rac-GR24 to achieve these effects.

Multi-omics analysis reveals metabolism of okadaic acid in gut lumen of rat.

Okadaic acid (OA) is an important marine lipophilic phycotoxin with various pathological properties, responsible for diarrheal shellfish poisoning events in human beings over the world. However, to date no mechanism can well explain the toxicity and symptom of OA, even diarrhea. Here, to reveal the toxic mechanism of OA to mammals, we analyzed the metabolism of OA in rat and the effects of OA exposure on the composition and function of gut bacteria using a multi-omics strategy and rRNA high-throughput technology. We found that OA exerted great effects on gut bacteria, mainly featured in heavy fluctuation of dominant genera and significant changes in the mapped bacterial function genes, including not only virulence genes of pathogenic bacteria, but also bacterial metabolism genes. In the feces of the OA-exposed group, we detected dinophysistoxin-2 (DTX-2), lespedezaflavanone F and tolytoxin, suggesting that OA could be transformed into other metabolites like DTX-2. Other metabolic biomarkers such as N-Acetyl-a-neuraminic acid, N,N-dihydroxy-L-tyrosine, nalbuphine, and coproporphyrin I and III were also highly correlated with OA content, which made the toxicity of OA more complicated and confusing. Spearman correlation test demonstrated that Bacteroides and Romboutsia were the genera most related to OA transformation, suggesting that Bacteroides and Romboutsia might play a key role in the complicated and confusing toxicity of OA. In this study, we found for the first time that OA may be converted into other metabolites in gut, especially DTX-2. This finding could not only help to reveal the complex toxicity of OA, but also have important significance for clarifying the transportation, metabolism, and environmental fate of OA in the food chain.

Emerging waste valorisation techniques to moderate the hazardous impacts, and their path towards sustainability.

Due to the recent boom in urbanisation, economy, and global population, the amount of waste generated worldwide has increased tremendously. The World Bank estimates that global waste generation is expected to increase 70% by 2050. Disposal of waste is already a major concern as it poses risks to the environment, human health, and economy. To tackle this issue and maximise potential environmental, economic, and social benefits, waste valorisation - a value-adding process for waste materials - has emerged as a sustainable and efficient strategy. The major objective of waste valorisation is to transit to a circular economy and maximally alleviate hazardous impacts of waste. This review conducts bibliometric analysis to construct a co-occurrence network of research themes related to management of five major waste streams (i.e., food, agricultural, textile, plastics, and electronics). Modern valorisation technologies and their efficiencies are highlighted. Moreover, insights into improvement of waste valorisation technologies are presented in terms of sustainable environmental, social, and economic performances. This review summarises highlighting factors that impede widespread adoption of waste valorisation, such as technology lock-in, optimisation for local conditions, unfavourable regulations, and low investments, with the aim of devising solutions that explore practical, feasible, and sustainable means of waste valorisation.

Effective bioremediation of tobacco wastewater by microalgae at acidic pH for synergistic biomass and lipid accumulation.

Tobacco wastewater is too difficult to decontaminate which poses a significant environmental problem due to the harmful and toxic components. Chlorella pyrenoidosa is a typical microalgal species with potential in removal of organic/inorganic pollutants and proves to be an ideal algal-based system for wastewater treatment. However, the strategy of tobacco related wastewater treatment using microalgae is in urgent need of development. In this study, C. pyrenoidosa was used to evaluate the removal efficiency of artificial tobacco wastewater. Under various solid-to-liquid (g/L) ratios, 1:1 ratio and acidic pH 5.0 were optimal for C. pyrenoidosa to grow with high performance of removal capacity to toxic pollutants (such as COD, NH3-N, nicotine, nitrosamines and heavy metals) with the alleviation of oxidative damage. Algal biomass could reach up to 540.24 mg/L. Furthermore, carbon flux of C. pyrenoidosa was reallocated from carbohydrate and protein biosynthesis to lipogenesis with a high lipid content of 268.60 mg/L at pH 5.0. Overall, this study demonstrates an efficient and sustainable strategy for tobacco wastewater treatment at acidic pH with the production of valuable microalgal products, which provides a promising biorefinery strategy for microalgal-based wastewater bioremediation.