C/N对蓝藻好氧堆肥腐熟及无害化进程的影响

为探索和优化脱水蓝藻藻泥好氧堆肥无害化处理工艺参数,利用堆肥反应器,研究了C/N分别为5（T1）、15（T2）和25（T3）的处理对蓝藻藻泥腐熟进程及微囊藻毒素（MC）降解速率的影响。结果表明,堆肥过程中各处理间的pH、总碳量及其形态、总氮量及其形态、总磷含量、总钾含量、种子发芽指数差异显著。与蓝藻自然堆置相比,添加辅料增加堆体C/N可提高蓝藻的腐熟速度。堆肥35d后,T2和T3处理的堆肥成品均已满足有机肥行业标准,种子发芽指数均高于80%;但MC-LR和MC-RR仍有较大的降解潜力,从无害化的角度考虑,蓝藻高温堆肥时间不应少于50d。C/N过高增加了氮素的损失,如何进一步降低氮素的损失,提高堆肥过程中MC的降解将是今后蓝藻堆肥研究的重点。     

蓝细菌对极端环境适应性研究进展

蓝细菌作为地球上最早出现的光合原核生物,它在生物进化过程中的独特性以及生态结构中的重要性使其成为研究热点。综述极端环境包括紫外辐照、异常温度、高盐3个因素对蓝细菌生理、生化、代谢及分子水平的影响,分析总结了蓝细菌在应对极端环境时屏蔽物质的产生特征及其适应机制。     

Genome Reduction and Secondary Metabolism of the Marine Sponge-Associated Cyanobacterium Leptothoe

Sponges form symbiotic relationships with diverse and abundant microbial communities. Cyanobacteria are among the most important members of the microbial communities that are associated with sponges. Here, we performed a genus-wide comparative genomic analysis of the newly described marine benthic cyanobacterial genus Leptothoe (Synechococcales). We obtained draft genomes from Le. kymatousa TAU-MAC 1615 and Le. spongobia TAU-MAC 1115, isolated from marine sponges. We identified five additional Leptothoe genomes, host-associated or free-living, using a phylogenomic approach, and the comparison of all genomes showed that the sponge-associated strains display features of a symbiotic lifestyle. Le. kymatousa and Le. spongobia have undergone genome reduction; they harbored considerably fewer genes encoding for (i) cofactors, vitamins, prosthetic groups, pigments, proteins, and amino acid biosynthesis; (ii) DNA repair; (iii) antioxidant enzymes; and (iv) biosynthesis of capsular and extracellular polysaccharides. They have also lost several genes related to chemotaxis and motility. Eukaryotic-like proteins, such as ankyrin repeats, playing important roles in sponge-symbiont interactions, were identified in sponge-associated Leptothoe genomes. The sponge-associated Leptothoe stains harbored biosynthetic gene clusters encoding novel natural products despite genome reduction. Comparisons of the biosynthetic capacities of Leptothoe with chemically rich cyanobacteria revealed that Leptothoe is another promising marine cyanobacterium for the biosynthesis of novel natural products.     

Hepatotoxic Seafood Poisoning (HSP) Due to Microcystins: A Threat from the Ocean?

Cyanobacterial blooms are a major and growing problem for freshwater ecosystems worldwide that increasingly concerns public health, with an average of 60% of blooms known to be toxic. The most studied cyanobacterial toxins belong to a family of cyclic heptapeptide hepatotoxins, called microcystins. The microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cell damage following cellular uptake via organic anion-transporting proteins (OATP). Their intracellular biologic effects presumably involve inhibition of catalytic subunits of protein phosphatases (PP1 and PP2A) and glutathione depletion. The microcystins produced by cyanobacteria pose a serious problem to human health, if they contaminate drinking water or food. These toxins are collectively responsible for human fatalities, as well as continued and widespread poisoning of wild and domestic animals. Although intoxications of aquatic organisms by microcystins have been widely documented for freshwater ecosystems, such poisonings in marine environments have only occasionally been reported. Moreover, these poisonings have been attributed to freshwater cyanobacterial species invading seas of lower salinity (e.g., the Baltic) or to the discharge of freshwater microcystins into the ocean. However, recent data suggest that microcystins are also being produced in the oceans by a number of cosmopolitan marine species, so that Hepatotoxic Seafood Poisoning (HSP) is increasingly recognized as a major health risk that follows consumption of contaminated seafood.     

Mineralization and Availability of Azolla and Cyanobacteria Biomass Nutrients in Rice Soil

Two sets of experiments were conducted to study the chemical composition, mineralization and availability of nutrients （particularly N） of Azolla biomass and cyanohacteria blooms in submerged rice soil. One set of experiment was conducted with Azolla without soil and the other with both Azolla and cyaobacteria with soil, in laboratory condition. Large samples were collected from the rice fields. The study shows that Azolla and cyanobacterial biomass contain good amounts of C, N, P and Ca. The chemical analysis of oxidizable C, total N, P and Ca showed that Azolla biomass contain 20.7% oxidizable C, which is higher than the cyanobacterial biomass （9.18%）. The N content in Azolla biomass was found to be 4.32%, than that of cyanobacterial biomass, i.e., 2.57%, however, P and Ca contents were also found to be higher in Azolla averaging to 124.83 ppm and 345.3 mg/100 g, respectively than cyanobacteria. The leachate analysis revealed that Azolla biomass release about 39.18% to 64.48% oxidizable C and about 19.23% to 33% N after 45 days of incorporation of soil dilution. Incorporation of Azolla and cyanobacterial biomass N@ 100 kg/ha significantly improved the oxidizable organic C, total as well as available N content in soil up to 75 days of incubation. Due to the incorporation of Azolla in soil, oxidizable organic C increased 25.51%, total N 4.10% and available N 47.65%. Almost similar trend of increase was also observed with the incorporation of cyanobacterial blooms.     

新疆特殊生境下微生物资源

概述了新疆大型真菌、新疆豆科植物根瘤菌、新疆陆生固氮蓝藻、新疆地衣、新疆极端环境微生物等5类微生物资源的研究进展和研究意义,同时指出了新疆微生物资源研究目前存在的两个重要盲区,即新疆非豆科植物共生固氮菌和新疆菌根真菌资源的研究,提出了这两个盲区研究的价值、意义、必要性和紧迫性。     

Hierridin B Isolated from a Marine Cyanobacterium Alters VDAC1, Mitochondrial Activity,and Cell Cycle Genes on HT-29 Colon Adenocarcinoma Cells

Background: Hierridin B was isolated from a marine cyanobacterium Cyanobium sp. strain and induced cytotoxicity selectively in HT-29 adenocarcinoma cells. The underlying molecular mechanism was not yet elucidated. Methods: HT-29 cells were exposed to the IC₅₀ concentration of hierridin B (100.2 μM) for 48 h. Non-targeted proteomics was performed using 2D gel electrophoresis and MALDI-TOF/TOF mass spectrometry. The mRNA expression of apoptotic and cell cycle genes were analyzed by real-time PCR. Automated quantification of 160 cytoplasm and mitochondrial parameter was done by fluorescence microscopy using CellProfiler software. Results: Proteomics identified 21 significant different proteins, which belonged to protein folding/synthesis and cell structure amongst others. Increase of VDAC1 protein responsible for formation of mitochondrial channels was confirmed by mRNA expression. A 10-fold decrease of cytoskeleton proteins (STMN1, TBCA) provided a link to alterations of the cell cycle. CCNB1 and CCNE mRNA were decreased two-fold, and P21CIP increased 10-fold, indicative of cell cycle arrest. Morphological analysis of mitochondrial parameter confirmed a reduced mitochondrial activity. Conclusion: Hierridin B is a potential anticancer compound that targets mitochondrial activity and function.     

Polymethoxy-1-alkenes from Aphanizomenon ovalisporum Inhibit Vertebrate Development in the Zebrafish (Danio rerio) Embryo Model

Cyanobacteria are recognized producers of a wide array of toxic or otherwise bioactive secondary metabolites. The present study utilized the zebrafish (Danio rerio) embryo as an aquatic animal model of vertebrate development to identify, purify and characterize lipophilic inhibitors of development (i.e., developmental toxins) from an isolate of the freshwater cyanobacterial species, Aphanizomenon ovalisporum.Bioassay-guided fractionation led to the purification, and subsequent chemical characterization, of an apparent homologous series of isotactic polymethoxy-1-alkenes (1–6), including three congeners (4–6) previously identified from the strain, and two variants previously identified from other species (2 and 3), as well as one apparently novel member of the series (1). Five of the PMAs in the series (1–5) were purified in sufficient quantity for comparative toxicological characterization, and toxicity in the zebrafish embryo model was found to generally correlate with relative chain length and/or methoxylation. Moreover, exposure of embryos to a combination of variants indicates an apparent synergistic interaction between the congeners. Although PMAs have been identified previously in cyanobacteria, this is the first report of their apparent toxicity. These results, along with the previously reported presence of the PMAs from several cyanobacterial species, suggest a possibly widespread distribution of the PMAs as toxic secondary metabolites and warrants further chemical and toxicological investigation.     

Cyanobacterial Toxic and Bioactive Peptides in Freshwater Bodies of Greece: Concentrations,Occurrence Patterns,and Implications for Human Health

Cyanobacterial harmful algal blooms represent one of the most conspicuous waterborne microbial hazards in aquatic environments mostly due to the production of toxic secondary metabolites, mainly microcystins (MCs). Other bioactive peptides are frequently found in cyanobacterial blooms, yet their concentration and ecological relevance is still unknown. In this paper we studied the presence and concentration of cyanobacterial peptides (microcystins, anabaenopeptins, anabaenopeptilides) in 36 Greek freshwater bodies, using HPLC-DAD, ELISA, and PP1IA. Microcystins were found in more than 90% of the samples investigated, indicating that microcystin-producing strains seem to also occur in lakes without blooms. Microcystins MC-RR, MC-LR, and MC-YR were the main toxin constituents of the bloom samples. Anabaenopeptin A and B were predominant in some samples, whereas anabaenopeptolide 90A was the only peptide found in Lake Mikri Prespa. The intracellular concentrations of anabaenopeptins produced by cyanobacterial bloom populations are determined for the first time in this study; the high (>1000 µg·L⁻¹) anabaenopeptin concentration found indicates there may be some impacts, at least on the ecology and the food web structure of the aquatic ecosystems. The maximum intracellular MC values measured in Lakes Kastoria and Pamvotis, exceeding 10,000 µg·L⁻¹, are among the highest reported.