Dynamic Analysis of an Algae-Bacteria Ecological Model

In the paper, under the framework of exploring the interaction between algae and bacteria, an algae-bacteria ecological model was established to analyze the interaction mechanism and growth coexistence mode between algicidal bacteria and algae. Firstly, mathematical work mainly provided some threshold conditions to ensure the occurrence of transcritical bifurcation and saddle-node bifurcation, which could provide certain theoretical support for selecting key ecological environmental factors and numerical simulations. Secondly, the numerical simulation work dynamically displayed the evolution process of the bifurcation dynamic behavior of the model (2.1) and the growth coexistence mode of algae and algicidal bacteria. Finally, it was worth summarizing that intrinsic growth rate and combined capture effort of algae population had a strong influence on the dynamic behavior of the model (2.1). Furthermore, it must also be noted that transcritical bifurcation and saddle-node bifurcation were the inherent driving forces behind the formation of steady-state growth coexistence mode between algicidal bacteria and algae. In summary, it was hoped that the results of this study would contribute to accelerating the study of the interaction mechanism between algicidal bacteria and algae.

Preliminary Study on Algae-lysing Active Substances of Algae-lysing Bacteria

Algae-lysing bacteria A1 has good control effect on the moss through its extracellular secretion. In order to further study its control mechanism, the sin- gle-factor tests of temperature and pH value, the activated carbon adsorption test, the organic solvent extraction test and the crude extract of active substance test were carried out to explore the characteristics of active substances. The results showed that the algae-lysing active ingredient of A1 strain had strong thermal stabili- ty, which still had good algae-lysing effect after being treated at 121 ℃ ; when the pH values of fermentation liquid were adjusted to 2.0 and 4.0 respectively, the active substances lost their activities, but their control ability against moss would be enhanced under the alkaline conditions ; the active substances could not be ad- sorbed by activated carbon; the algae-lysing active substances showed strong hydrophilie ability when they were extracted by ethyl acetate, petroleum ether and chloroform. Therefore, it could be speculated that the active substances belonged to carbohydrates. The crude extract results of algae-lysing active substances showed that the active substances secreted by A1 strain were composed by a variety of algae-lysing active substances.

<i>In Vitro</i>Antibacterial Activity of Flavonoid Extracts of Two Selected Libyan Algae against Multi-Drug Resistant Bacteria Isolated from Food Products

This study aimed to evaluate the antibacterial activity of flavonoids extracted from two Libyan brown algae namely Cystoseira compressa and Padina pavonica using microwave-assisted extraction method against pathogenic bacteria isolated from meat, meat products, milk and dairy products (Staphylococcus aureus subsp. aureus (5 isolates), Bacillus cereus (3 isolates), Bacillus pumilus (1 isolate), Salmonella enterica subsp. enteric (4 isolates) and Enterohaemor-rhagic Escherichia coli O157 (EHEC O157) (4 isolates)). All of these isolates were muti-drug resistant with high MAR index. The results showed that C. compressa extract exhibited better and stronger antibacterial activities against the seventeen tested isolates with inhibition zones diameter ranged from 14 - 22 mm compared to P. pavonica extract which showed positive effect against 9 isolates with low inhibition zone ranged from 11 - 16.5 mm. Flavonoids extracted from C. compressa also displayed the best spectrum of bactericidal effect with a ratio MBC/MIC ≤ 4 obtained on all susceptible tested bacterial strains. Flavonoids and proanthocyanidins significantly contributed to the antibacterial properties. The mode of action of these active extracts is under investigation.

Dose and time response of ruminally infused algae on rumen fermentation characteristics,biohydrogenation and Butyrivibrio group bacteria in goats

Background： Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid （UFAs）. This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, biohydrogenation and Butyrivibrio group bacteria in goats. Methods： Six goats were used in a repeated 3 x 3 Latin square design, and offered a fixed diet. Algae were infused through rumen cannule with 0 （Control）, 6.1 （L-AIg）, or 18.3 g （H-AIg） per day. Rumen contents were sampled on d 0, 3, 7, 14 and 20. Results： H-AIg reduced total volatile fatty acid concentration and acetate molar proportion （P 〈 0.05）, and increased propionate molar proportion （P 〈 0.05）, whereas L-AIg had no effect on rumen fermentation. Changes in proportions of acetate and propionate in H-AIg were obvious from d 7 onwards and reached the largest differences with the control on d 14. Algae induced a dose-dependent decrease in 18：0 and increased trons-18：1 in the ruminal content （P 〈 0.05）. H-AIg increased the concentrations of t9, t] 1-18：2 and tl 1, cl 5-18：2 （P 〈 0.05）. L-AIg only seemed to induce a transient change in 18-carbon isomers, while H-AIg induced a rapid elevation, already obvious on d 3, concentrations of these fatty acid rose in some cases again on d 20. Algae had no effect on the abundances of Butyrivibfio spp. and Butyrivibrio proteoclosdcus （P 〉 0.10）, while H-AIg reduced the total bacteria abundance （P 〈 0.05）. However, this was induced by a significant difference between control and H-AIg on d 14 （-4.43 %）. Afterwards, both treatments did not differ as increased variation in the H-AIg repetitions, with in some cases a return of the bacterial abundance to the basal level （d 0）. Conclusions： Changes in rumen fermentation and 18-carbon UFAs metabolism in response to algae were related to the supplementation level, but there was no evidence of shift in ruminal biohydrogenation pathways towards t1 0-18：1 L-AIg mainly induced a transient effect on rumen biohydrogenation of 18-carbon UFAs, while H-AIg showed an acute inhibition and these effects were not associated with the known hydrogenating bacteria.

Shewanella algae对纯锌腐蚀性能的影响

【目的】在室内模拟条件下研究海藻希瓦氏菌(Shewanella algae)对纯锌牺牲阳极腐蚀的影响。【方法】利用微生物分析、交流阻抗测试技术、扫描电镜及荧光显微等方法,测试Shewanella algae的生长曲线、开路电位、电化学阻抗、表面形貌等。【结果】在含细菌体系中,细菌通过代谢活动消耗掉溶解氧,在试样表面形成一层生物膜。该生物膜阻挡了腐蚀介质与试样表面的接触,从而使试样的腐蚀受到抑制。荧光显微镜观察结果表明,浸泡7d,试样表面形成完整的生物膜,但随着营养物质及氧气的消耗,生物膜逐渐脱落。【结论】该细菌可以使纯锌试样的腐蚀电位升高,并且显著抑制试样的腐蚀。该细菌生物膜的形成需要一定的时间及充足的营养物质和氧气。

Metabolic relationships between marine red algae and algae‑associated bacteria

Mutualistic interactions between marine phototrophs and associated bacteria are an important strategy for their success-ful survival in the ocean,but little is known about their metabolic relationships.Here,bacterial communities in the algal sphere(AS)and bulk solution(BS)of nine marine red algal cultures were analyzed,and Roseibium and Phycisphaera were identified significantly more abundantly in AS than in BS.The metabolic features of Roseibium RMAR6-6(isolated and genome-sequenced),Phycisphaera MAG 12(obtained by metagenomic sequencing),and a marine red alga,Porphyridium purpureum CCMP1328(from GenBank),were analyzed bioinformatically.RMAR6-6 has the genetic capability to fix nitrogen and produce B vitamins(B1,B2,B5,B6,B9,and B12),bacterioferritin,dimethylsulfoniopropionate(DMSP),and phenylacetate that may enhance algal growth,whereas MAG 12 may have a limited metabolic capability,not producing vitamins B9 and B12,DMSP,phenylacetate,and siderophores,but with the ability to produce bacitracin,possibly modulating algal microbiome.P.purpureum CCMP1328 lacks the genetic capability to fix nitrogen and produce vitamin B12,DMSP,phenylacetate,and siderophore.It was shown that the nitrogen-fixing ability of RMAR6-6 promoted the growth of P.pur-pureum,and DMSP reduced the oxidative stress of P.purpureum.The metabolic interactions between strain RMAR6-6 and P.purpureum CCMP1328 were also investigated by the transcriptomic analyses of their monoculture and co-culture.Taken together,potential metabolic relationships between Roseibium and P.purpureum were proposed.This study provides a bet-ter understanding of the metabolic relationships between marine algae and algae-associated bacteria for successful growth.

Isolation and identification of bacteria associated with the surfaces of several algal species

We conducted this study to assess the diversity of bacteria associated with the surfaces of algae based on 16S rDNA sequence analyses.Twelve strains of bacteria were obtained from the surfaces of the following four species of algae:Gracilaria textorii,Ulva pertusa,Laminaria japonica,and Polysiphonia urceolata.The isolated strains of bacteria can be divided into two groups:Halomonas and Vibrio,in physiology,biochemical characteristics and 16S rDNA sequence analyses.The phylogenetic tree constructed based on 16S rDNA sequences of the isolates shows four obvious clusters,Halomonas venusta,Vibrio tasmaniensis,Vibrio lentus,and Vibrio splendidus.Isolates from the surface of P.urceolata are more abundant and diverse,of which strains P9 and P28 have a 16S rDNA sequence very similar(97.5%-99.8%) to that of V.splendidus.On the contrary,the isolates from the surfaces of G.textorii,U.pertusa and L.japonica are quite simple and distribute on different branches of the phylogenetic tree.In overall,the results of this study indicate that the genetic relationships among the isolates are quite close and display a certain level of host species specificity,and alga-associated bacteria species are algal species specific.

Isolation and algae-lysing characteristics of the algicidal bacterium B5

Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillusfusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that： （1） the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; （2） the algal-lysing effects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesrnus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 × 10^7 cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 μg/L, about 70% was removed; （3） the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.

冰封期不同类型湖泊细菌与蓝藻群落组成及共现网络分析

季节性冰封使得寒区湖泊微生物群落结构及生物间的相互反馈具有特殊性。黄河流域内蒙古段湖泊作为典型的寒区湖泊,其漫长的冰封期为研究细菌与蓝藻在冰封条件下的相互关系提供了天然平台。解析不同类型湖泊生态系统中细菌与蓝藻群落间的相互关系差异,有助于深入理解湖泊冰封条件下水生态系统的功能与动态。为探明湖泊功能对菌藻关系的影响,本文以大型淡水湖泊乌梁素海、城市湖泊南海湖、咸水湖泊岱海冰封期冰下水体为研究对象,利用宏基因测序分子生物学技术、冗余分析、Mantel检验分析及Network网络分析模型等方法,对冰封期间细菌和蓝藻群落结构及相互关系进行研究。结果表明:3个湖泊冰下水体中优势菌门组成一致,属水平上的群落组成具有较为明显的差异;湖泊间菌藻群落组成差异与环境因子的协同作用高度相关,总磷、氨氮和总氮是影响冰封期菌藻群落结构的主要环境因子;细菌-蓝藻的微生物网络复杂性呈现南海湖>岱海>乌梁素海。岱海网络中菌藻关系多以负相关为主,负权重边占比达到31.70%,且模块化程度较高。本文旨在对湖泊冰下水体中的细菌、蓝藻群落结构及共现网络进行深入分析,以更好地理解不同水生态系统下微生物错综复杂的关系,为相关领域的生态保护和研究提供重要的理论依据。

菌藻共生技术在畜禽养殖沼液资源化治理领域的研究进展

我国规模化畜禽养殖场快速发展,大量经过厌氧处理的养殖沼液的治理与资源化利用成为污水治理领域的研究热点之一。介绍了传统生化处理法与微藻技术在沼液资源化治理中的不足与瓶颈,以及菌藻共生技术在沼液治理与资源化领域的兴起与发展,进一步根据菌藻共生系统的作用机理与沼液处理效能,系统论述了菌藻共生技术研究现状,包括反应器的开发及应用,功能菌种、藻种的选择,菌藻接种比的确定和菌藻颗粒污泥的开发等。最后,分析了菌藻共生技术在沼液治理与资源化领域的研究方向,提出未来菌藻颗粒污泥资源化技术将是沼液资源化处理技术的重点研究方向之一。

固定化菌藻填料强化人工湿地去除营养盐和PFOS效果研究

针对全氟辛烷磺酸(Perfluorooctane Sulfonate, PFOS)污染现状,开展3种人工湿地去除复合污染水体中营养盐和全氟辛烷磺酸的效果研究。选取普通垂直流人工湿地(Constructed Wetlands, CW)、固定化菌人工湿地(Immobilized Bacteria Constructed Wetlands, IB-CW)和固定化菌藻填料人工湿地(Immobilized Bacteria Algal Constructed Wetlands, IBA-CW)为研究对象,通过露天试验研究3种湿地在不同质量浓度PFOS下对水体中污染物的去除效果。结果显示,3种湿地对水体中的营养盐和PFOS均具有较好的去除能力,且PFOS对各营养盐的去除具有一定的影响。高质量浓度(100μg/L)PFOS抑制风车草生长,CW植物PFOS质量比达到试验最高值,为(100.56±3.28)μg/g, IB-CW和IBA-CW风车草的总生物量分别比CW增加了10.73%和18.52%。低质量浓度(1μg/L)PFOS促进风车草的生长,IBA-CW风车草总生物量达到了试验最高值,与未加PFOS的处理组相比,生物量增长了16.05%。在高质量浓度PFOS胁迫下,3种人工湿地化学需氧量(Cemical Oxygen Demand, COD)、NH3-N、总氮(Total Nitrogen, TN)和总磷(Total Phosphorus, TP)的去除效果均有所降低。其中,与对照组(无PFOS)相比,IBA-CW对COD、NH3-N、TN、TP的去除率分别降低了(4.23±0.21)百分点、(10.50±0.45)百分点、(13.33±0.51)百分点和(6.87±0.25)百分点,比其他两种湿地降幅小。3种人工湿地均可以有效去除废水中的PFOS,IBA-CW对PFOS的去除率优于CW和IB-CW。3种人工湿地中填料吸附占比均大于植物占比,IBA-CW中填料贡献率比CW高12.90百分点,比IB-CW高5.51百分点。

不同碳源下共存细菌对铜绿微囊藻生长的影响

铜绿微囊藻(Microcystis aeruginosa)可通过二氧化碳浓缩机制(carbon concentrating mechanism,CCM)利用水环境中的无机碳进行光合固碳来促进自身生长,是引发淡水蓝藻水华的优势种。自然水体生态系统中菌藻共生体系是其重要组成部分,对藻华起到重要调控作用,但有关不同碳源条件下共生细菌对蓝藻藻华的影响仍不清楚。文章以铜绿微囊藻为模式蓝藻,探究在不同碳源组合下共存细菌对其生长的影响。在总碳(total carbon,TC)质量浓度为25 mg/L的无机碳源和有机碳源组合,环境初始菌藻比为1∶2时,铜绿微囊藻的最大生物量达到最大值5.0×10^(7)个/mL,是纯藻对照组最大生物量的2.05倍;在加入25 mg/L的有机碳源,初始菌藻比为5∶1时,培养周期内可预测的最大生物量达到最小,为1.5×10^(7)个/mL,仅为纯藻对照组最大生物量的0.76倍。结果表明:不同碳源下初始细菌的出现会极大程度地影响铜绿微囊藻的生长,其中,在无机碳源和混合碳源的营养条件下,初始细菌显著加快了铜绿微囊藻的生长繁殖。

生物吸附剂在含重金属离子废水处理中的研究进展

高效、节能、环保的含重金属离子废水处理技术是如今的研究重点之一,生物吸附法因其对环境友好的特性以及优秀的吸附性能,在含重金属离子废水处理的领域内有着较大的潜力。近些年来,国内外研究者从酵母、生物质、细菌、藻类等方面对生物吸附剂进行探索研究,以期让其更好的应用于实际。主要是从生物吸附剂材料分类和生物吸附机理两方面,对目前的生物吸附剂研究进展进行总结和归纳,并对其未来的发展做出相应展望。

地中海弧菌117-T6的溶藻活性

为验证地中海弧菌117-T6(Vm 117-T6)是否具有广谱溶藻性,本实验观察了其对赤潮异湾藻、颗石藻、叉鞭金藻和东海原甲藻的溶藻作用,并对其溶藻物质的特性进行了分析。结果表明,紫菜黄斑病致病菌Vm 117-T6对赤潮异湾藻、颗石藻、叉鞭金藻和东海原甲藻等微藻具有较强溶藻活性,可使藻类叶绿素含量显著降低,是一株广谱性溶藻细菌。Vm 117-T6能在40 min内使赤潮异弯藻的活动能力下降,光合作用受抑,感染120 min即可导致藻体裂解并产生白色絮状沉淀。该菌株能降解卡拉胶,不能降解果胶、纤维素和几丁质。Vm 117-T6菌体、胞内及胞外提取物均具有较强的溶藻活性,其胞外溶藻物质易溶于水、不溶于石油醚和乙酸乙酯,具较强极性;耐高温、不易被活性炭吸附、乙醇处理会降低溶藻活性。Vm 117-T6在常规与易感条件下的关键差异蛋白包括大量的ABC转运蛋白、外膜蛋白、鞭毛蛋白及少量毒素。上述结果提示,Vm 117-T6毒力效应物中含有极性的内毒素物质,且与毒力因子转运、分泌以及细胞黏附相关的蛋白可能在其毒力作用中发挥重要作用。本实验为解析该菌株溶藻机制提供了证据,为该菌的防治及应用提供了参考。

土霉素对菌藻共生系统去除营养盐的影响机制探究

为明确新污染物土霉素(OTC)对藻-菌共生系统去除营养盐的影响及作用机制,通过控制进水OTC浓度,在反应温度30℃和进水有机负荷5.1~5.6 g/L的条件下,考察了OTC对藻-菌共生系统处理畜禽养殖废水的影响并揭示了相关机制。结果表明,低剂量(低于0.1 mg/L)OTC对藻-菌共生系统影响不明显,当高剂量(>0.5 mg/L)OTC显著降低了污染物及氮磷的去除效率。高剂量OTC降低了藻菌共生系统内污泥浓度,降低了污泥沉降性及叶绿素a产量但刺激了可溶性有机质的释放。高剂量OTC降低了微生物的活性,在4.0 mg/LOTC暴露组别内,比耗氧速率(SOUR)下降至26.7 mg O_(2)/(g VSS·h)。微生物学分析高剂量OTC降低了Proteobacteria和Bacteroidota门级别微生物,norank_f__Saprospiraceae属级别微生物。研究结果为藻-菌共生系统处理含抗生素废水提供了一定的数据支撑和理论依据。

小球藻-好氧污泥耦合颗粒的培养及处理特性研究

在实验室条件下培养出好氧颗粒污泥作为生物载体,接种小球藻形成菌藻共生颗粒污泥(Algal-bacterial granular sludge,ABGS),探究不同光照强度对ABGS系统去除污染物效果的影响,重点考察了5 klx光照强度下小球藻对ABGS系统处理能力的增强作用。结果表明,在0~100 klx光照强度范围内,ABGS对COD、TN和TP的去除率分别为87.01%~95.32%、53.14%~89.37%和32.49%~99.40%,同步硝化反硝化率(SND)为7.70%~83.66%;而单一小球藻系统对TP和TN的去除率仅为20%~30%,对COD去除效果不明显。在一定光照强度范围内,小球藻可以提高水中DO,并通过促进ABGS系统中细菌的代谢速率来促进污染物的降解。随着光照强度的增强,ABGS系统对COD和TP的去除率上升,对TN的去除率下降,SND下降。过低或过高的光照强度均会抑制小球藻的光合作用甚至使其死亡,导致ABGS破裂解体,系统崩溃,污染物去除效果变差。高通量分析表明,藻类的加入进一步扩大了与氮磷代谢相关的菌种相对丰度,增强了系统的脱氮除磷效果。

金纳米颗粒绿色合成研究进展

制备金纳米颗粒(gold nanoparticles,AuNPs)中绿色合成法主要表现出制备流程简单,环境友好并可能具有协同生物效应的优点。本文简要综述了近年来以植物、藻类、真菌和细菌等天然试剂为原材料绿色合成AuNPs的研究进展。当前金纳米颗粒的绿色合成法存在制备过程中形状和表面修饰可控性不足,多组分萃取液合成过程当中涉及的完整机理和确切的代谢产物仍不十分清楚等问题,还需要进行详细研究,以拓展金纳米颗粒在生物医药领域的应用。

菌藻颗粒污泥工艺在城市污水处理中的研究

菌藻颗粒污泥(Algal-bacterial granular sludge,ABGS)工艺是一种节能高效的低碳污水处理工艺。本研究采用10L序批式光反应器,针对ABGS的快速启动进行了研究。通过将绿藻投加到好氧颗粒污泥中,30天左右实现了ABGS工艺的快速启动。丝状藻类与丝状菌交织形成颗粒骨架,胞外聚合物(Extracellular Polymeric Substances,EPS)的大量分泌促进了微生物的聚集,进而促进了ABGS的快速形成。稳定的ABGS系统内,氨氮(NH4_(+)—N)、COD和总氮(TN)的去除率分别达到了99%、92%和70%。正磷酸盐(PO_(4)^(3-)—P)的去除率受进水磷浓度和COD浓度影响而不太稳定。系统内发酵菌、聚糖菌和反硝化聚磷菌得到了良好的富集。

水环境中藻类与细菌有益相互作用的研究进展与展望

藻类和细菌在生态系统中重要元素的生物地球化学循环、能量流动等过程中具有重要作用。一些细菌可以通过促进藻类生长、帮助藻类抵抗逆境胁迫等作用,与藻类发生有益相互作用,进而对两者的生存、竞争、生理功能方面均产生重要影响。本文对近年来藻类和细菌有益相互作用的主要方式、微生物类群、分子机制,及其在环境污染处理、生物质能源和合成生物学等方面的应用进展进行综述,并对未来研究提出展望。这不仅对理解水体微生物的群落结构与功能、微生物种间关系的机制与效应具有重要作用,也将为维护生态系统的健康、挖掘和利用生物资源造福人类提供重要的科学依据。

C/N对HN-AD菌藻颗粒污泥体系处理农村污水的影响

通过在传统菌-藻共生好氧颗粒污泥体系(ABGS)中引入异养硝化-好氧反硝化(HN-AD)菌构建H-ABGS体系,以合成农村污水为研究对象,考察碳氮比(C/N=1,2,4,6,8,10)对H-ABGS系统中污染物去除性能和微生物特性影响.结果表明,C/N为4时,H-ABGS系统的总氮去除率高于ABGS系统(12.05%)和好氧颗粒污泥(AGS)系统(44.86%).微生物群落分析显示,适应低碳环境的Thauera菌属和脱氨关键菌属norank_f__A4b可能是确保H-ABGS系统在低碳环境下具备高脱氮性能的关键.微生物群落的共生模式和相关性分析表明,引入HN-AD菌有助于最小化生态位,与藻共同形成稳定的共生体系,从而确保系统的稳定性.此外, C/N为4时,高表达的硝酸还原酶可能有助于确保H-ABGS系统在低碳环境下具备卓越的脱氮性能.