Cadmium (Cd) accumulation in rice poses a significant threat to food safety and human health. Plant growth-promoting endophytes (PGPEs) offer a promising strategy to mitigate Cd stress. Yet, the mechanisms underlying microbe-mediated reduction of Cd uptake, particularly through specific plant-microbe interactions, remain poorly understood. Here, we demonstrate that the root endophyte Bacillus sp. RE35, a Cd-tolerant and high-IAA producer isolated from rice, established an effective apoplastic niche and significantly enhanced Cd retention in roots through a multi-level mechanism. Successful colonisation of RE35 in the root apoplast, confirmed by the red fluorescent protein labelling, strain-specific gene quantification and colonisation-related genes analysis, promoted extensive root morphological remodelling via both de novo and salvage pathways of IAA biosynthesis under Cd stress. Notably, RE35 inoculation drastically reshaped Cd distribution, increasing cell wall-bound Cd by 64.7% while reducing shoot Cd accumulation by 24.1%-49.7%. This enhanced apoplastic trapping of Cd was attributed to a comprehensive cell wall remodelling program, activated through RE35-induced expression of plant receptor kinases (e.g., LRR-RLKs, LysM-RLKs) and the upregulation of key genes involved in the biosynthesis of pectin, hemicellulose and lignin. In parallel, RE35 modulated host Cd transport by downregulating influx transporter genes (OsNRAMP5, OsZIP5/9) and upregulating the vacuolar sequestration gene OsHMA3. Our findings reveal a Cd-responsive regulatory network where endophytes enhance apoplastic immobilisation by coordinating auxin signalling, receptor kinase activation and cell wall remodelling, providing a mechanistic basis for sustainable agriculture in contaminated environments.

Toxic cyanobacteria can generate various bioactive metabolites, posing serious risks to aquatic organisms. Entire cyanobacteria cells-induced adverse influences on fish populations could be more complicated than cyanotoxins or extracts of cyanobacteria. Current scientific research usually focuses on the ecotoxicological effects of planktonic cyanobacteria or their cyanotoxins or their crude extracts while ignoring the harmful impacts of benthic cyanobacteria. This project investigated the harmful effects of two algal bloom-relevant densities (5 x 105 cells/mL and 10 x 105 cells/mL) of planktonic Microcystis aeruginosa (generating microcystin (MC)) and benthic Oscillatoria sp. (generating cylindrospermopsin (CYN)) on the filtering-feeding juvenile silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) under a short-time exposure (14 d). The data indicated that both silver carp and bighead carp can filtrate Microcystis rather than Oscillatoria by measuring the level of cyanotoxins. Both Microcystis and Oscillatoria can cause oxidative stress, neurotoxicity, apoptosis, and inflammation in the brain and liver of two kinds of filtering-feeding fish. Furthermore, both Microcystis and Oscillatoria can perturb many terms and pathways related to the immune responses in the liver of two types of fish based on the transcriptomics analysis, which could explain the observed inflammatory reactions in this study. Interestingly, the differentially expressed genes showed that both silver carp and bighead carp were more sensitive to benthic Oscillatoria than planktonic Microcystis. This study will contribute to a better mechanistic understanding of the harmful effects of different kinds of toxic cyanobacteria, suggesting that the adverse impacts and ecological risks of benthic cyanobacteria require further exploration.

Specialized pro-resolving mediators (SPMs), derived from polyunsaturated fatty acids (PUFAs), exhibit dual immunomodulatory and inflammation-resolving properties. Given microalgae' rich PUFA content and capacity to biosynthesize SPMs precursors, this study investigated Spirulina platensis, Phaeodactylum tricornutum (P. tricornutum), Haematococcus pluvialis, and Schizochytrium sp. Microalgal oils, extracted via accelerated solvent extraction (ASE), were evaluated using a Pseudomonas aeruginosa-Caenorhabditis elegans infection model. All oils significantly improved nematode survival, with P. tricornutum oil at 100 mu g/mL showing the highest efficacy (51.61 % lifespan extension versus infected controls). Mechanistically, the oils upregulated antioxidant (sod-3 and daf-16) and innate immunity genes (K08D8.5, lys-1, and spp-1), mitigated oxidative stress, and enhanced infection resistance. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identified SPMs (e. g., lipoxin B4, 15-epimer-lipoxin A4, and resolvin 1-4) in P. tricornutum oil, while all four microalgal oils contained oxylipin (13-hydroxyoctadecadienoic acid). This study is the first to demonstrate the immune-enhancing capacity of microalgal oils in Caenorhabditis elegans, while also identifying the presence of various SPMs in P. tricornutum oil. These findings lay the foundation for using microalgal oils as a source for SPMs production and for developing novel immune-enhancing agents.

Dietary intake is a predominant pathway of human exposure to environmental Cadmium (Cd), but wheat (Triticum aestivum L.) has not received enough concerns for its risk of Cd contamination. A field survey of Cdcontaminated rice-wheat rotation farmlands in China provided detailed comparison of Cd accumulation capacity by rice and wheat grains. The results indicated that Cd-BCF of wheat grains (median values 0.42) were obviously higher than those of rice grains (median values 0.12) under wide soil Cd levels and pH ranges. Soil Cd levels rather than pH played a vital role on Cd accumulation by wheat grains, and high wheat grain Cd concentrations (0.12-0.13 mg kg-1) were even observed in mildly alkaline soil that normally have low Cd mobility. Dietary Cd exposure risks were assessed by the crop Cd exposure models considering different soil Cd content, pH and dietary structures of residents. The results indicated that the intake of wheat grains contributed 56.1-86.5% of total crop Cd exposure, with an increase in its contribution with the increase of soil pH. Residents favoring wheat would have a significant Cd exposure risk if consuming crops from soils with Cd levels above 0.41 mg kg-1, which was considerably lower than the current soil Cd risk screening value for alkaline soils (0.6 mg kg-1). Our findings indicate a high Cd accumulation capacity of wheat grains and consequent risk of dietary Cd exposure, which deserves further exploration on the correlation among soil Cd screening value, grain Cd limit value and its dietary exposure risk.

The concurrent presence of cyanobacterial blooms and cyanobacterial derivative pollution in natural freshwater poses serious threats to aquatic biota and human beings. To date, cyanobacteria, especially ignored benthic toxic cyanobacteria, may cause potential harmful impacts on benthic animals. Understanding benthic animals' possible responses to these toxic cyanobacteria is important for assessing cyanobacterial bloom-induced ecological risks. This study investigated the harmful impacts of planktonic Microcystis aeruginosa (generating microcystin) and benthic Oscillatoria sp. (generating cylindrospermopsin) on the feeding behavior, tissue structure, neurotoxicity, oxidative stress, and immunotoxicity of the freshwater macrobenthos clams Lamprotula leai and snails Bellamya aeruginosa under 14-d exposure. Firstly, two cyanobacteria can reduce the clearance rates of clams and snails, causing tissue damage in their digestive glands. Secondly, two cyanobacteria can induce neurotoxicity in clams and snails by altering acetylcholinesterase activities and acetylcholine levels in their digestive glands. Thirdly, two cyanobacteria can lead to oxidative stress in clams and snails by changing the antioxidant enzyme activities, glutathione levels, malondialdehyde levels, and reactive oxygen species levels in their digestive glands. Finally, two cyanobacteria can cause immunotoxicity in clams and snails by altering lysozyme activities in their digestive glands, while two cyanobacteria can also induce inflammatory responses in clams by increasing levels of interleukin-1β and tumor necrosis factor-α in their digestive glands. These data indicated that toxic cyanobacteria can threaten the health of macrobenthos, and the benthic cyanobacteria-induced adverse ecological impacts should not be ignored.

Cyanobacterial blooms can generate various toxic metabolites in freshwater, and pose serious threats to drinking water safety and human health. Although microcystins (MCs) have been detected in many freshwater ecosystems in China, little is known about the other cyanotoxins. An investigation of six eutrophic lakes (i.e. Hulun Lake, Wuliangsuhai Lake, Chaohu Lake, Taihu Lake, Xingyun Lake, and Dianchi Lake) in different geographical locations of China was performed during the summer of 2022 to determine the occurrence of various cyanotoxins (i.e. anatoxin-a (ATX), cylindrospermopsin (CYN), and MCs) in water column and their possible risks, and to evaluate the related environmental factors. MCs levels in sediment of these lakes were also investigated. MCs were the primary cyanotoxins in the water column of investigated lakes. The mean MCs contents in water column of Hulun Lake, Wuliangsuhai Lake, Chaohu Lake, Taihu Lake, Xingyun Lake, and Dianchi Lake were 3.61, 0.13, 3.60, 2.18, 0.57, and 2.56 mu g/L, respectively. The total MCs levels in water column exceeded 1 mu g/L in some areas of these lakes except Wuliangsuhai Lake. Replete nitrogen and/or phosphorus levels seemed to be related to MCs production. ATX can be detected in these lakes except Xingyun Lake at ng/L levels. CYN can be detected in all lakes at ng/L levels. However, the levels of ATX and CYN appear to be not significantly associated with environmental factors. MCs and CYN can pose a high or moderate risk for humans and aquatic organisms in some areas of these lakes, while ATX can pose a low or no risk for humans and aquatic organisms in most areas of these lakes. MCs can also be detected in sediment of all lakes at ng/g levels. This research emphasizes the necessity for long-term monitoring of different cyanotoxins in eutrophic lakes, and the implementation of nutrient control and management strategies.

A promising solution to combat harmful cyanobacterial blooms (CyanoHABs) is the use of naturally-derived cyanocidal compound. This study found that the crude extracts of the herbaceous plant Macleaya cordata can inhibit the growth of the bloom-forming cyanobacterium Microcystis aeruginosa. Growth inhibition test suggested that the inhibitory effect was significant at a concentration as low as 5 μg/L of the crude extracts. To comprehensively elucidate inhibitory mechanisms, we examined the responses in anti-oxidative systems, changes in triggering signals in cells, and hallmarks of programmed cell death (PCD) under the two levels of exposure to the crude extracts of M. cordata. A notable observation across all treatment groups was the significant increase in the superoxide dismutase activity of M. aeruginosa at 72 h. However, distinct patterns were observed in malondialdehyde (MDA), with no significant difference observed between the low concentration treatment group (5 μg/L) and the control group. In contrast, Microcystis cells subjected to high concentration (10 μg/L) exhibited a significant difference in MDA content at both 24 and 72 h. Furthermore, we observed that the levels of potential signaling molecules, e.g., intracellular reactive oxygen species, nitric oxide, and Ca2+ were altered in the Microcystis cells after exposure to the crude extracts. This results in alterations to the levels of signaling molecules, which in turn stimulate the upregulation of orthocaspase, leading to PCD and population collapse eventually. This study examines the mechanisms of Microcystis suppression through naturally-derived substances, providing theoretical and technical foundations for the sustainable management of CyanoHABs.

To examine the impact of antibiotic contamination on water quality and rhizospheric microbial communities, a simulated cultivation experiment was employed to investigate the potential impacts of tetracycline (Tet) stress on water quality and microbial community composition in the rhizosphere of Eichhornia crassipes (E. crassipes), with a focus on its implications for bioremediation strategies. The results showed a significant disruption in microbial diversity and community structure in the rhizosphere at varying accumulated Tet concentrations (0, 2, 5, and 10 mg·L−1). The microbial communities displayed resilience and functional stability from the low (2 mg·L−1) to moderate (5 mg·L−1) accumulated Tet concentrations; while significant root decay and a marked decline in microbial diversity were observed at the high (10 mg·L−1) accumulated Tet concentration. Some bacterial taxa, including Rhizobiaceae (0.34%), Comamonadaceae (0.37%), and Chitinophagaceae (0.38%), exhibited notable enrichment under Tet stress, underscoring their functional roles in nitrogen cycling, organic matter decomposition, and antibiotic degradation. Physicochemical changes in the rhizosphere, such as shifts in low-molecular-weight organic acids (LMWOAs), nutrient cycling, and total organic carbon (TOC), revealed Tet-induced metabolic adaptations and environmental alterations. Correlation analysis between environmental factors and dominant operational taxonomic units (OTUs) highlighted the putative intricate interplay between microbial activity and Tet stress. These findings underscore the dual impact of Tet as both a stressor and a selective agent, favoring antibiotic-resistant taxa while suppressing sensitive groups. This study provides foundational insights into the ecological and functional dynamics of microbial communities under antibiotic contamination conditions and highlights the potential of rhizospheric microbial communities in the rhizosphere for bioremediation in Tet-polluted ecosystems.

The widespread use of fomesafen, a diphenyl ether herbicide, has resulted in the accumulation of residues in soils of legume crop fields, potentially disrupting the dynamics of rhizospheric nitrogen-fixing microbial communities. However, such knowledge remains to be systematically pursued. This study employed field experiments to evaluate the impact of different fomesafen dosages on modulating nitrogen-fixing microbial community structure in rhizosphere of six legume species and their microbial network interactions across three seasons. The findings revealed that fomesafen significantly reduced the abundance of nifH genes in legume rhizospheres, with 16.7 %- 43.5 % of nitrogen-fixing genera showing significant changes in abundance. Species-specific recruitment of rhizospheric microbes by legumes with differing sensitivities to fomesafen, coupled with fomesafen dosage, played a pivotal role in shaping nitrogen-fixing microbial communities. Correlation analysis highlighted a strong relationship between changes in symbiotic nitrogen-fixing bacteria and plant health. Co-occurrence network analysis further demonstrated that fomesafen disrupted microbial interactions by reducing edge density and altering network connectivity. Nonetheless, symbiotic rhizobia, including Rhizobium and Sinorhizobium, accounted for 53.3 %-91.7 % of the connector module in the network, maintaining key roles in nitrogen cycling and herbicide degradation to support plant health and productivity. This study provides essential insights into the adaptation mechanisms of the rhizospheric nitrogen-fixing microbial community of different legume species to fomesafen stress, offering guidance for the development of sustainable practices that enhance legume nitrogen fixation and reduce soil herbicide residues.

Sinudenoids B-D are a class of C19-norcembranoids characterized by a unique [5-5-6-6] tetracyclic architecture and notable bioactivities, which present significant synthetic challenges. We herein disclose an efficient strategy for the asymmetric construction of their common [5-6-6] tricyclic core. Our approach features two pivotal advancements: (1) a convergent strategy employing Julia-Kocienski olefination for efficient fragment coupling and (2) a tandem oxidation/intramolecular Diels-Alder (IMDA) sequence that stereoselectively establishes the [5-6-6] tricyclic core.

The oxidation of biochar occurs due to both natural and human influences during the soil carbon sequestration process. Therefore, it is crucial to produce high-stability biochar to achieve carbon neutrality. Fly ash-doped biochar was obtained from fly ash and corn stalks by employing hydrothermal/pyrolysis treatment, along with alkali impregnation at different temperatures. The microstructural characteristics and carbon sequestration potentials were studied as an essential performance parameter that was influenced by mineral doping and treatment temperature. The yield and carbon retention of P500-1:2 improved by 54.15 • Fly ash-doping is more effective in enhancing carbon retention and chemical oxidation resistance in pyrolysis biochar compared to hydrothermal biochar. • Doping with fly ash improved the microstructure and promoted the aromatization of pyrolysis biochar, benefiting carbon retention. • As the temperature increased, the carbon retention of fly ash-doped biochar gradually decreased, with the rate of change stabilizing. • The addition of fly ash facilitated the formation of Si-C/Al-C bonds, contributing to the chemical oxidation resistance of the biochar.

Nitrous oxide (N2O) is a potent greenhouse gas and contributor to ozone depletion, with wastewater treatment plants (WWTPs) serving as significant sources of emissions due to biological processes involving bacteria. This study evaluates research on the role of bacteria in N2O emissions from WWTPs between 2000 and 2023 based on an analysis of the Web of Science Core Collection Database using keywords “bacteria”, “nitrous oxide”, “emission”, and “wastewater treatment plant”. The findings reveal substantial research growth in the past decade, with leading publications appearing in Water Research, Bioresource Technology, and Environmental Science & Technology. China, the United States, and Australia have been the most active contributors to this field. Key topics include denitrification, wastewater treatment, and N2O emissions. The microbial community composition significantly influences N2O emissions in WWTPs, with bacterial consortia playing a pivotal role. However, further research is needed to explore strain-specific genes, enzyme expressions, and the differentiation of processes contributing to N2O production and emission. System design and operation must also consider dissolved oxygen and nitrite concentration factors. Advances in genomics and artificial intelligence are expected to enhance strategies for reducing N2O emissions in WWTPs.

Ferrihydrite (Fh) interaction with organic matter is crucial for Cr(III) adsorption. Extensive application of biochar releases biochar-derived dissolved organic matter (DBC) into groundwater. Significant variations were observed between DBC and natural organic matter in terms of functional group composition and aromaticity. Mechanism of DBC and Fh interaction and its contribution to Cr(III) removal are currently unclear. This study investigated removal of Cr(III) by organic-Fh composites (OFCs) synthesized by DBC, humic acid (HA), and fulvic acid (FA) with Fh at C/Fe molar ratios of 0.5 (OFC-BC0.5, OFC-HA0.5, and OFC-FA0.5) and 2 (OFC-BC2, OFC-HA2, and OFC-FA2). OFC-BC0.5 was enriched with Brunauer-Emmett-Teller (BET)-specific surface area (SBET), oxygen-containing functional group, and aromaticity compared to OFC-HA0.5 and OFC-FA0.5. Phenolic groups and aromatic rings in DBC were preferentially adsorbed by Fh. Increased DBC content significantly reduced the SBET and total pore volume of OFC-BC2, obscuring Fh-surface binding sites. OFC-BC0.5 exhibited greater adsorptive affinity for Cr(III) than OFC-HA0.5 and OFC-FA0.5. The affinity of OFCs for Cr(III) substantially decreased as the C/Fe molar ratio increased from 0.5 to 2. The Cr(III) adsorption by OFC-BC2 decreased by 31 % compared to that by OFC-BC0.5. The Cr(III) adsorption by OFC-BC0.5 increased with increasing pH and ionic strength. The primary adsorption mechanisms were inner-sphere complexation, Cr(III)-pi interaction, and (Cr, Fe) (OH)3 precipitation. The C--O,-COOH functional groups and benzene rings had the most stable binding capacity to Cr(III). The study provides molecular level evidence that the interaction of DBC and Fh adsorbs Cr(III), improving understanding of the fate of Cr and exploring repair strategies.

Cadmium (Cd) contamination has become an emergent environmental issue in agroecosystems worldwide. The impacts of Cd on microbial community and their ecological functional remain unrevealed. This study investigated the response of bacterial community and microbial ecological functions to Cd contamination in paddy soil of East China. Bacterial diversity and community structure significantly changed under Cd contamination. Proteobacteria and Acidobacteria were identified as biomarkers to indicate Cd contamination. The overall elemental cycling genes abundance was negatively correlated to soil Cd content. Acetyl-CoA synthesis, organic N mineralization, N fixation and nitrous reduction genes were especially sensitive to elevated Cd stress, resulting in loss of microbial derived soil C and N pool and increase in N2O emission potential. Bacteria interactions were sparser yet more competitive under Cd contamination. Cd resistant genera Massilia, Burkholderia, Streptomyces and Methylobacterium were essential to bacterial interactions via building connections with non-resistant species. Microbial Cd immobilization potential by urea hydrolysis was enhanced under Cd contamination, with Massilia being the keystone functional taxa involved in this process. Our study elucidated the ecological risks of altered microbial functions under Cd contamination in paddy soil, as well as the significance of Cd resistant bacteria to microbial community and ecological functionality.

The cadmium (Cd) contamination in agricultural land has been attracting much attention worldwide due to its potential health risks. Rice grown in the polluted field may pose a serious threat to human health through dietary intake because its high Cd enrichment ability leads to Cd accumulation in the grain. It has been shown that plant endophytes have the ability to immobilize Cd, but there are few studies reporting the characteristics of rice endophytes with high Cd tolerance, and their Cd-immobilizing mechanisms under different concentrations of Cd need further studies. In this article, a liquid adsorption test was conducted to investigate the Cd tolerance and immobilizing mechanisms of the rice root endophyte Bacillus sp. RE35 that was previously screened for high Cd tolerance. The results showed that the maximum Cd tolerance concentration of strain RE35 could reach 600 mg/L, the maximum adsorption capacity was 28.49 mg/g, and the removal rates of 1 and 5 mg/L Cd2+ were 88.37% and 80.40%, respectively. The stain can tolerate such high concentrations of Cd equivalent to the stains isolated from Cd-contaminated soil. The strain RE35 showed distinct Cd accumulation and adsorption mechanisms at different Cd concentrations. When Cd concentration was lower than 20 mg/L, Cd2+ removal by strain RE35 was dominated by intracellular accumulation. The production of siderophores, as a possible transport carrier of Cd, was greatly reduced under Cd treatment, indicating that siderophores did not have significant contribution to the intracellular accumulation of Cd by the strain RE35. The determination of ATPase activities showed that they increased significantly with the increase of Cd concentrations, and it was speculated that the intracellular transport of Cd by strain RE35 may be related to ATP-dependent metal transporters. The distribution of Cd inside strain RE35 cells was investigated by high-resolution transmission electron microscopy and energy dispersive spectroscopy, and the results revealed that Cd was uniformly distributed in the cytoplasm of the cells. When the concentration of Cd was higher than 20 mg/L, the intracellular Cd accumulation of strain RE35 reached saturation, whereas the extracellular adsorption amount rose significantly with increasing Cd concentrations and gradually exceeded the intracellular accumulation. The production of protein component in the extracellular polymeric substances (EPS) by strain RE35 was positively related to the amount of Cd extracellular adsorption. The results of scanning electron microscopy and energy dispersive spectroscopy showed that more EPS appeared on the cell surface with the increase of Cd concentrations, and Cd adsorption on the cell surface was detected at the Cd concentration of 70 mg/L as well. The characterization of chemical groups on the cell surface by X-ray photoelectron spectroscopy and Fourier transform infrared absorption spectroscopy showed that the -NH2, amide I (C=O) and amide II (-NH, -CN) groups of extracellular proteins were involved in the Cd extracellular adsorption by the strain RE35. The rice root endophyte Bacillus sp. RE35 exhibited relatively high resistance and removal capacity of Cd2+. When the Cd concentration was lower than 20 mg/L, strain RE35 removed Cd2+ in solution mainly by intracellular accumulation, and when the Cd concentration increased, it was mainly through extracellular adsorption. The intracellular accumulation of Cd by strain RE35 might be related to ATP-dependent metal transporters, and at higher Cd concentrations, the strain could effectively adsorb Cd extracellularly through the secretion of EPS in addition to accumulating intracellularly. The amino and amide groups of proteins in EPS were closely related to the extracellular adsorption of Cd. This study elucidated the Cd accumulation and adsorption mechanisms of strain RE35 with high Cd tolerance under different Cd concentrations, providing valuable information on a strain resource for the development of endophyte microbial agents in the future.

Total carbohydrate analysis with phenol‑sulfuric acid method is the simplest method among many colorimetric and modern instrument analytical methods. It has great potential to be used as a rapid screening method for characterization of algal biomass for algae-based biofuel research. The reproducibility and accuracy of the conventional phenol‑sulfuric method remain to be improved when applied directly to algal biomass. In the present study, several important factors that influenced the colorimetric determination were characterized and methods to eliminate the influences were further developed. Results indicated that system temperature and the addition mode of sulfuric acid and phenol were the key parameters which affected the color development and reproducibility of the conventional methods. A new design using the premixed reagent replacing the individual phenol and sulfuric acid solution solved this problem ideally. The color inferences caused by algal pigments including chlorophylls and carotenoids were quantitatively analyzed. Solutions for reducing overestimation of total carbohydrates were also addressed. In addition, hydrolysis conditions for algae biomass such as type of acids, temperature, and time were also investigated and optimized in this study. The new modified phenol‑sulfuric acid method has been shown to be more reproducible and reliable than the conventional methods for the analysis of total carbohydrates from algal biomass.

Astaxanthin is an economically valuable carotenoid pigment, and most natural astaxanthin is produced via the large-scale cultivation of the green alga Haematococcus pluvialis in outdoor culture systems. The effects of various environmental factors on Haematococcus and the physiological response of algal cells have rarely been investigated at commercial production scale, which are important for maximizing the yield and efficiency of algae production. This study found that the light intensity and cumulative light intensity are the most important factors affecting the biomass production and astaxanthin accumulation in outdoor large-scale cultivation of Haematococcus based on a year-round survey, and the cumulative light intensity between 550 and 850 mol photons.m(-2) was an optimal range for a reasonable productive harvest. The temperature, diurnal temperature difference, culture period and initial inoculation concentration were found to be associated with production performance. Light requirements for green cell growth and for astaxanthin accumulation of immotile cells were quite different, the late showed a very high tolerance to light intensity. Under high light intensity or low temperature, nonphotochemical quenching seemed to play a role in quenching excess energy in red immotile spore cells. This study provided detailed information on Haematococcus biomass production and astaxanthin accumulation at big commercial scale via tubular photobioreactors, which is valuable for improvement of commercial production of Haematococcus.

The Chroococcales is one of the least studied cyanobacterial orders comprising the non-baeocyte-producing coccoids cyanobacteria with stacked and fasciculated thylakoids. During a survey of aquatic biodiversity in Caohai Lake in Guizhou Province, China, a coccoid-like cyanobacterium was isolated. It was characterized using a polyphasic approach, based on morphology, electron microscopy, and molecular phylogenetic analyses. This species’ colonies exhibited morphological similarity to those of Microcystis species but differed in their larger colony sizes and widely oval cells. The 16S rRNA gene sequence of this species had the maximum homology, corresponding to 93.10%, to that of the genus Microcystis. The results of 16S rRNA gene threshold value and 16S rRNA phylogenetic analyses confirmed that the studied species belongs to the family Microcystaceae but is phylogenetically distinct from the other species of Microcystaceae. Furthermore, The D1–D1′, Box–B helix, and V3 helix of the 16S–23S ITS region were also different from those previously described in Microcystaceae taxa. Combining the morphological, ecological, and molecular features of the coccoid-like cyanobacterium, we here propose the establishment of the Cyanodorina gen. nov. and the Cyanodorina ovale sp. nov.

Fomesafen, a broad-spectrum herbicide with a long duration, is frequently applied in legume farmlands, causing severe damage to crop growth and the local environment. Sinorhizobium sp. W16 was a fomesafen-degrading rhizobium isolated from a soybean nodule. The pure culture assay revealed that strain W16 efficiently degraded 5 mg L-1 of fomesafen by 69 % over 7 days. Three metabolites were identified by liquid chroma-tography and time-of-flight mass spectrometry, revealing strain W16 was the first strain isolated to catalyze the cleavage of ether bond of fomesafen. The results of the pot experiment demonstrated that strain W16 colonizes the soybean rhizosphere for over 50 days and eliminates the inhibition of fomesafen on nitrogen fixation by increasing the activity of nitrogenase and stimulating the indigenous nitrogen-fixing microbes in the rhizosphere. The symbiotic relationship between strain W16 and legumes promotes soil fomesafen degradation rates by 29.17 %-57.87 %. This study provides valuable information about a novel fomesafen-degrading rhizobium with great potential for promoting the bioremediation of herbicide-contaminated farmland soil due to the development of symbiotic systems with legumes.

The most widely used colorimetric method based on the phenol-sulfuric acid system generally has problems of poor reproducibilities and large measurement errors. In this study, bioactive Tremella fuciformis polysaccharides (TFPS) were used as the test materials, a systematic investigation was performed to solve these problems. Influences of temperature, TFPS hydrolysis, enzyme interferences, and other factors affecting the TFPS determination were intensively studied and optimized. The accurate quantification of TFPS in the presence of enzyme interference was also innovatively realized by the establishment of corrected calibration standard curves. In addition, long-term storage conditions of TFPS samples at different temperatures and storage time were also addressed and compared. This study, for the first time, completely solved the problems that existed in traditional phenol-sulfuric acid methods and thereby provided a certain theoretical basis not only for accurate detection and quantification of TFPS but for standardization and further utilization of other types of polysaccharides as well.