室内水生动物对蓝藻生长的抑制效果

在室内模拟小水体中,开展了不同密度尼罗罗非鱼和鲢鱼抑制蓝藻生长的对比试验.结果表明:尼罗罗非鱼和鲢鱼对水体中蓝藻绿藻过量增长均有不同程度的抑制作用,其中尼罗罗非鱼抑制消除蓝藻的效果优于鲢鱼,且尼罗罗非鱼的密度越高抑制消除蓝藻的速度越快;尼罗罗非鱼对水体中营养盐水平消除无明显贡献,但能有效提高水体的透明度,降低水体的pH值.     

Changes in the photosynthetic activity of Microcystis colonies after gut passage through Nile tilapia (Oreochromis niloticus) and silver carp (Hypophthalmichthys molitrix)

The photosynthetic activity of cyanobacteria (predominantly Microcystis spp.) after passage through the digestive tract of Nile tilapia (Oreochromis niloticus) and silver carp (Hypophthalmichthys molitrix) was determined by CCD fluorescence imaging, using slow complementary area approach, during a 4‐day cultivation of fish faeces in algal ZBB medium. The cyanobacteria colonies exhibited a 92–95% reduction in of activity (P<0.001) after passage through Nile tilapia, whereas there was a significant (P<0.01) stimulation of photosynthetic activity after passage through the silver carp gut.     

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。     

蓝藻沼液对蔬菜产量、品质的影响及替代化肥作用研究

通过蓝藻沼液替代不同化肥和沼液用量田间试验,研究蓝藻沼液与不同化肥用量间、不同蓝藻沼液用量间蔬菜产量、硝酸盐、维生素C(VC)的差异,并分析蓝藻沼液应用蔬菜的化肥替代作用。结果表明:①小白菜连续2茬施用蓝藻沼液,第1、2茬的产量效应分别与蓝藻沼液中氮、磷、钾养分量的72.3%、85.6%化肥相同,替代化肥率第1茬比第2茬增加18.4%。②与等养分量的化肥相比,施用蓝藻沼液有降低小白菜硝酸盐含量和提高VC含量的作用;连续施用有提高VC含量的后效,但无降低小白菜硝酸盐含量的作用。③蓝藻沼液用量对菜椒产量、VC的调控作用均呈显著的开口向下的抛物线关系,对硝酸盐含量呈显著线性正相关关系;产量与品质相协调的蓝藻沼液用量为134.1～138.9t.hm-2。     

干旱与重吸水对人工藻结皮光合特性的影响

通过接种蓝藻构建人工藻结皮促进荒漠地区生物结皮的生长发育以及整个荒漠生态系统的恢复,被认为是一种行之有效的荒漠化控制方法。在构建藻结皮过程中,接种的蓝藻以及形成的藻结皮,经常遭受干旱等环境条件的胁迫。本研究通过室内人工构建藻结皮,对形成的藻结皮进行干旱及重吸水处理,在此过程中监测结皮光合生物量、多糖含量以及结皮光合特性的变化规律。结果发现,干旱处理1d后,结皮蓝藻胞外多糖的分泌明显增加(p0.05);当结皮完全进入干燥状态后,结皮蓝藻停止所有代谢活动,结皮生物量及胞外多糖含量保持在一个相对稳定的水平。在结皮重吸水后,结皮初始荧光Fo能够迅速恢复,并在10 min内达到最大;之后Fo逐渐下降,同时结皮光合活性(Fv/Fm)按照函数y=ax/(b+x)逐渐上升并达到稳定。此外,在不同水分条件下,结皮光合活性随着水分的增加逐渐增加;然而结皮净光合速率(Pn)却随着水分的增加先增加后又下降,呈现单峰变化模式。该研究表明结皮蓝藻的代谢调节在人工藻结皮适应荒漠干旱环境中具有重要的作用,这对于进一步理解蓝藻乃至蓝藻结皮对干旱胁迫的适应,以及荒漠化防治中人工藻结皮的构建、维护、管理具有重要的理论与实践意义。     

蓝藻酸解产物成分及其饲用安全性研究

为了利用太湖蓝藻的蛋白质资源,开发新型饲料产品,本试验采用盐酸水解法研究蓝藻酸解产物中氨基酸组成及残留的微囊藻毒素和重金属含量,并进行动物急性毒理试验,研究其饲用安全性。结果表明:蓝藻经盐酸水解14 h后,酸解产物中氨基酸种类达17种,氨基酸总量达52.63%,其中畜禽必需氨基酸总量为30.25%,微囊藻毒素-LR残留量为1.33μg/kg。蓝藻酸解18 h产物中微囊藻毒素-LR残留量为0.90μg/kg(低于饮用水限量标准1.0μg/L),且微囊藻毒素-LR和微囊藻毒素-RR去除率均高于99.99%。蓝藻酸解14 h产物中重金属砷(As)、铅(Pb)、汞(Hg)、铬(Cr)的含量均远低于相关国家标准的限量。小鼠急性毒性试验、小鼠骨髓嗜多染红细胞微核试验和小鼠精子畸形试验测试的蓝藻酸解产物的饲用安全性结果表明:蓝藻酸解物的小鼠半致死剂量(LD50)>9.09 g/kg BW,属于实际无毒的毒性级别;微核试验和致畸试验检测结果均显示为阴性,蓝藻酸解产物无致突变性和无精子致畸性。由此得出,蓝藻酸解14 h产物的氨基酸总量超50%且畜禽易缺乏而常添加的赖氨酸、蛋氨酸、苏氨酸含量较高;蓝藻经酸解14 h以上,其产物中微囊藻毒素残留量接近饮用水限量标准,急性毒理评价为无毒、无致突变性、无精子致畸性。     

Effects of cyanobacteria strains selected for their bioconditioning and biofertilization potential on maize dry matter and soil nitrogen status in a South African soil

Abstract

Some cyanobacteria strains have biofertilization and/or bioconditioning effects in soils as a result of their ability to fix dinitrogen or produce exocellular polysaccharides. The objective of the present study was to screen indigenous cyanobacteria strains with the potential to improve the N fertility and structural stability of degraded soils, and evaluate their ameliorative effectiveness in semiarid soils of the Eastern Cape, South Africa. Soils from Guquka, Hertzog and Qunu villages, and Fort Cox College were used in the screening study. The results showed that only three cyanobacteria strains (3g, 3v and 7e) out of 97 isolated strains were heterocystous, with appreciable nitrogenase activity and the ability to produce exocellular polysaccharides. Nostoc strains 3g and 3v had a greater ability to produce exocellular polysaccharides, but low potential to fix dinitrogen (4.7 and 1.3?nmol C₂H₄?μg^?1?chl?h^?1, respectively). Strain 7e had the greatest ability to fix dinitrogen (16.1?nmol C₂H₄?μg^?1?chl?h^?1), but produced fewer exocellular polysaccharides. The ability of strains 3g and 7e to influence maize dry matter (DM) and soil C and N contents was tested in a nitrogen-poor soil with Nostoc strain 9v as a reference strain. Potted soils with and without growing maize plants were inoculated with the different cyanobacteria strains in a glasshouse at a rate of 6?g?m^?2 soon after maize emergence. Harvesting and soil sampling were done 6?weeks after inoculation. Inoculation with strains 3g and 7e increased maize DM and N uptake significantly, on par with the reference strain. These increases were consistent with increases in nitrate-N observed at harvest time in inoculated cropped and non-cropped soils. Strain 7e resulted in greater increases in soil nitrate-N, tissue N and uptake than strain 3g, perhaps because of its greater ability to fix dinitrogen. Cropping with maize reduced soil total C and N, possibly owing to its negative effects on cyanobacteria establishment. These results suggest that indigenous cyanobacteria strains screened for greater N₂-fixing ability have the potential to improve the productivity of N-poor soils in semiarid regions in South Africa.     

Current Knowledge on Microviridin from Cyanobacteria

Cyanobacteria are a rich source of secondary metabolites with a vast biotechnological potential. These compounds have intrigued the scientific community due their uniqueness and diversity, which is guaranteed by a rich enzymatic apparatus. The ribosomally synthesized and post-translationally modified peptides (RiPPs) are among the most promising metabolite groups derived from cyanobacteria. They are interested in numerous biological and ecological processes, many of which are entirely unknown. Microviridins are among the most recognized class of ribosomal peptides formed by cyanobacteria. These oligopeptides are potent inhibitors of protease; thus, they can be used for drug development and the control of mosquitoes. They also play a key ecological role in the defense of cyanobacteria against microcrustaceans. The purpose of this review is to systematically identify the key characteristics of microviridins, including its chemical structure and biosynthesis, as well as its biotechnological and ecological significance.     

A Multi-Omics Characterization of the Natural Product Potential of Tropical Filamentous Marine Cyanobacteria

Microbial natural products are important for the understanding of microbial interactions, chemical defense and communication, and have also served as an inspirational source for numerous pharmaceutical drugs. Tropical marine cyanobacteria have been highlighted as a great source of new natural products, however, few reports have appeared wherein a multi-omics approach has been used to study their natural products potential (i.e., reports are often focused on an individual natural product and its biosynthesis). This study focuses on describing the natural product genetic potential as well as the expressed natural product molecules in benthic tropical cyanobacteria. We collected from several sites around the world and sequenced the genomes of 24 tropical filamentous marine cyanobacteria. The informatics program antiSMASH was used to annotate the major classes of gene clusters. BiG-SCAPE phylum-wide analysis revealed the most promising strains for natural product discovery among these cyanobacteria. LCMS/MS-based metabolomics highlighted the most abundant molecules and molecular classes among 10 of these marine cyanobacterial samples. We observed that despite many genes encoding for peptidic natural products, peptides were not as abundant as lipids and lipopeptides in the chemical extracts. Our results highlight a number of highly interesting biosynthetic gene clusters for genome mining among these cyanobacterial samples.     

Bridging Cyanobacteria to Neurodegenerative Diseases: A New Potential Source of Bioactive Compounds against Alzheimer’s Disease

Neurodegenerative diseases (NDs) represent a drawback in society given the ageing population. Dementias are the most prevalent NDs, with Alzheimer’s disease (AD) representing around 70% of all cases. The current pharmaceuticals for AD are symptomatic and with no effects on the progression of the disease. Thus, research on molecules with therapeutic relevance has become a major focus for the scientific community. Cyanobacteria are a group of photosynthetic prokaryotes rich in biomolecules with confirmed activity in pathologies such as cancer, and with feasible potential in NDs such as AD. In this review, we aimed to compile the research works focused in the anti-AD potential of cyanobacteria, namely regarding the inhibition of the enzyme β-secretase (BACE1) as a fundamental enzyme in the generation of β-amyloid (Aβ), the inhibition of the enzyme acetylcholinesterase (AChE) lead to an increase in the availability of the neurotransmitter acetylcholine in the synaptic cleft and the antioxidant and anti-inflammatory effects, as phenomena associated with neurodegeneration mechanisms.