光合细菌对鲤养殖水体生态系统的影响

光合细菌(Photosynthetic Bacteria,简称PSB)是一种不放氧光合作用的细菌总称,近年来,光合细菌在理论和应用上都受到了广泛的重视,一方面由于它是研究光合作用的理想材料,另一方面,它又有广泛的应用价值.光合细菌在处理高浓度有机废水,生产单细胞蛋白,水产养殖和禽畜饲养,改善植物营养状况等方面已有不少报道1-4,本文研究了光合细菌在鲤养殖水体中的增殖和分布规律以及它对水体中异养细菌、浮游动物及水质的影响,以阐明光合细菌在该生态系统中的作用.       

高效光合细菌菌剂对土壤微生物的影响

为了筛选在盆栽试验条件下适宜的高效光合细菌菌剂浓度以促进番茄生长,研究了高效光合细菌菌剂的3种浓度对番茄种植土壤中微生物特性的影响。试验结果表明：高效光合细菌菌剂的施用可以显著提高土壤中细菌和放线菌的数量,降低土壤中真菌数量;不同程度提高土壤脲酶、酸性磷酸酶和过氧化氢酶的活性。其中以稀释100倍的光合细菌菌剂+化肥处理效果最明显,稀释100倍的菌剂+化肥处理最有利于土壤中微生物的生长繁殖,对土壤环境的改善效果最显著。     

几种重金属离子对光合细菌生长的抑制效应

光合细菌因其在自然生态系统中的意义与较大的应用价值 ,一直受到国内外科学工作者的重视 ,无论基础研究 ,还是应用研究 ,都取得了重大的进展。其应用研究主要为 3方面 :①用于高负荷有机废水处理 ;②用于水产养殖。它具有作为养殖水质净化剂、用于鱼虾贝幼体培育、作为动物性生物饵料的饵料、作为成鱼成虾的饲料添加剂、防治病等方面作用[6] ;③在农业上的应用。在光照嫌气条件下 ,大多数细菌能有效地固定Ｎ2 ,故在淹水的耕作土壤(如水稻田 )里 ,它能提高土壤Ｎ素水平 ,从而提高土壤肥力 ,光合细菌还能氧化或分解土壤中Ｈ2 Ｓ和胺等有毒化…     

光合细菌在水污染治理中的研究进展

光合细菌以其无毒、繁殖快、适应能力强、易人工培养等优点而在环境治理中受到重视。国内外对光合细菌的研究主要集中在水产养殖业(如净化水质,作饵料添加剂等)和生活及工业重污染水处理中的作用,关于光合细菌在景观微污染水体治理方面的作用研究较少。课题组研究发现光合细菌中的沼泽红假单胞菌对西南大学景观水中氨氮的去除率高达95%,暗示光合细菌能有效治理景观水污染。综述了光合细菌的分类、脱氮除磷原理以及目前光合细菌在治理有机废水、重金属废水和养殖污水方面的应用,并展望了光合细菌在处理景观微污染水体方面的应用前景,以期为进一步研究光合细菌在景观水治理中的作用提供参考。     

固定化微生物菌剂与蕹菜对中华鳖养殖污水的净化效果研究

为解决中华鳖(Trionyx sinensis)养殖所造成的水环境污染问题,研究利用海藻酸钠、沸石对复合光合菌剂和枯草芽孢杆菌菌剂分别进行固定化,并研究了不同固定化微生物菌剂与蕹菜对中华鳖养殖污水的净化效果。结果表明:净化处理15d后,利用固定化微生物菌剂与蕹菜共同处理组对中华鳖养殖污水的净化处理效果最好,养殖污水的CODMn、NH 4+-N、NO3-N、NO 2-N、PO34的去除率分别为88.7%、87.3%、90.8%、98.3%、74.9%。蕹菜处理组对于NO3-N、NO 2-N、NH 4+-N的去除率显著高于固定化复合光合菌剂处理组和固定化枯草芽孢杆菌处理组。固定化复合光合菌剂处理组对于NO3-N、NO 2-N、NH 4+-N的去除率显著高于固定化枯草芽孢杆菌菌剂处理组,但固定化枯草芽孢杆菌处理组对于污水的CODMn的去除率最高,可达90.6%。     

光合细菌对水产养殖水质和水生生物的影响

研究光合细菌对水产养殖水体的水质,如化学需氧量(COD)、氨氮(NH₄⁺-N)、溶解氧(DO)、pH等指标,及对水生生物,如藻类植物和细菌的种群组成的影响。结果表明:鲤鱼养殖水中投放一定量的光合细菌,能明显去除水中有机物和NH₄⁺-N,增加DO的含量,稳定pH值。光合细菌对水中藻类也有明显影响,0.50%、1%剂量组中藻类明显增加,其中硅藻在所有藻类中所占比例可达26%以上,绿藻所占比例达60%左右,而以蓝藻为主的杂藻则下降到10%左右。光合细菌对有害菌有一定的抑制作用,使得弧菌属、气单胞菌属等致病菌所占比例显著降低。     

针对细胞壁合成途径的抗菌药物研究进展

细胞壁是细菌区别真核生物的一个重要特征,因此其合成途径早已成为人们广泛研究的抗菌药物靶标来源.目前临床上上广泛应用的抗生素,如β内酰胺类(青霉素、头孢菌素类等)和糖肽类(万古霉素等)抗生素主要就是通过阻断细菌的细胞壁合成而起到杀菌作用[1].     

微生物菌剂施用对设施茄子根际土壤养分和细菌群落多样性的影响

[背景]设施茄子连作种植和化学肥料过量施用造成土壤养分失衡、微生物多样性降低、土传病害严重等土壤质量问题,微生物制剂是改善土壤环境质量的一项重要措施。[目的]确定微生物菌剂施用对设施茄子根际土壤养分及细菌群落多样性的影响。[方法]在河北省农林科学院鹿泉大河实验园区,以含有哈茨木霉和巨大芽孢杆菌的微生物菌剂为供试菌剂,采用传统的化学分析方法测定微生物菌剂处理和对照茄子开花期、拉秧期土壤的养分含量;采用稀释涂平板方法测定土壤可培养微生物的数量;采用高通量测序技术测定土壤细菌16S rRNA基因V3-V4区,分析处理和对照土壤的微生物多样性和群落分布规律。[结果]与对照相比,微生物菌剂处理提高了茄子开花期和拉秧期的根际土壤养分含量,拉秧期微生物菌剂处理根际土壤中全氮、碱解氮、有效磷、速效钾含量分别较对照增加13.85%、21.07%、31.51%和55.94%;施用微生物菌剂能够改变土壤可培养微生物的数量和构成,微生物菌剂处理土壤中细菌、真菌、放线菌的数量均显著增加,其中细菌、放线菌在微生物总量中所占比例增加,而真菌的占比则有所降低。微生物菌剂处理能够提高土壤微生物的Shannon指数、降低Simpson指数,ACE指数和Chao1指数差异不显著,表明微生物菌剂能够增加土壤的微生物群落多样性,对微生物群落丰富度影响不明显。从目水平上分析菌剂处理和对照的微生物组成,发现微生物菌剂处理增加了土壤中黄单胞菌目(Xanthomonadales)、红螺菌目(Rhodospirillales)、鞘脂杆菌目(Sphingobacteriales)、芽孢杆菌目(Bacillales)、纤维黏网菌目(Cytophagales)、假单胞菌目(Pseudomonadales)等优势菌目的占比,降低了伯克氏菌目(Burholderiales)、黄杆菌目(Flavobacteriales)等病原菌的占比。微生物菌剂的施入能够促进茄子营养生长,增加茄子的产量,增幅为18.52%。[结论]微生物菌剂作为一种新型环保肥料,具有改善土壤营养状况、增加土壤可培养微生物数量、提高土壤微生物多样性的作用,该结果为微生物菌剂的合理施用提供了科学依据。     

环境对沼泽红假单胞菌基因型的影响

<正>紫色光合细菌是不产氧光合细菌的一个重要分支,包括紫色非硫细菌和紫色硫细菌。其中紫色非硫细菌具有极其丰富的代谢模式,可进行光能异养、光能自养和化能异养生长,其代谢的多样性使得它们广泛存活于不同的生态系统中,如土壤、湖泊、海洋及底泥等[1-2]。沼泽红假单胞菌(Rhodopseudomonas palustris)是紫     

一株反硝化光合细菌的生物学特性及系统发育分析

【目的】养殖水体中亚硝酸盐的过量积累会对养殖生物产生毒害作用,应用脱氮细菌去除亚硝酸盐是养殖水质调控的重要手段之一,本文意在得到一株高效去除亚硝酸盐的光合细菌。【方法】采用软琼脂稀释法分离纯化光合细菌菌株,通过电镜观察、生理生化试验研究其生物学特性、依据16S rDNA和光合反应中心M亚基基因(Gene coding for photosynthetic reaction center subunit M,pufM)序列对其做系统发育分析。【结果】从淡水养殖塘中分离筛选到一株高效还原亚硝氮的光合细菌菌株wps。该菌株为革兰氏阴性菌,细胞杆状,大小为0.4-0.6μm×1.5-4.0μm,极生丛生鞭毛,片层状光合内膜,兼性厌氧光照条件生长,单菌落及液体培养物呈红色,含细菌叶绿素a和类胡萝卜素。最适生长pH范围为5.5-8.5,最适生长盐度范围为0-2%,最适生长温度范围为25℃-38℃。菌株wps与Rhodopseudomonas palustris的16S rDNA序列相似性为98.9%,光合反应中心M亚基基因序列的相似性为94.9%,但是二者在生物学性质上有较大差异,如菌株wps在pH5.5生长,不能光自养生长,不利用柠檬酸盐、甲酸盐进行光异养生长,需盐酸硫胺素和泛酸钙做生长因子等。【结论】菌株wps可能为Rhodopseudomonas属的一个新种,且在养殖水体水质调控中具有重要应用前景。     

Effects of dissolved oxygen on key enzyme activities during photosynthetic bacteria wastewater treatment

Photosynthetic bacteria (PSB) wastewater treatment is a novel method that can simultaneously achieve wastewater purification and recourse recovery. Oxygen conditions can significantly influence PSB metabolism and wastewater treatment; however, the roles of key enzymes in this process have been unclear. This study investigated the effects of different oxygen conditions on respiratory enzymes (hexokinase, HK; phosphofructokinase, PFK; and pyruvate kinase, PK) and the photosynthetic enzyme RuBisCO of PSB. The results showed that HK activity was almost the highest under anaerobic condition; PFK activity was the highest (311 nmol/min∙g) and PK the most quickly reached its peak under aerobic condition; and RuBisCO activity was the highest (107 nmol/min g) under anaerobic condition. The above results illustrated that HK might simultaneously regulate PSB growth and COD degradation, and its main role might be PSB growth regulation. PFK and PK might function in COD degradation while RuBisCO might function in PSB growth. Further, oxygen was beneficial for COD degradation and detrimental for PSB growth. This study provides a theoretical basis for the development of PSB wastewater treatment.     

Comparison of Two Methods for Enumeration of Anaerobe Numbers on Forages and Evaluation of Ethylene Oxide Treatment for Forage Sterilization

Experiments were conducted to (i) compare most-probable-number (MPN) procedures with roll tube procedures for enumeration of forage anaerobic bacteria and (ii) evaluate the efficacy of using ethylene oxide to sterilize wet herbage. Alfalfa, corn, and alfalfa-orchardgrass silages and alfalfa and orchardgrass herbages were analyzed for total anaerobic bacteria (medium pH, 6.8) and acid-tolerant anaerobic bacteria (medium pH, 4.5) by both roll tube and MPN procedures. No difference was found between the roll tube and MPN procedures for total bacteria; however, higher counts were obtained for acid-tolerant bacteria when the MPN procedure was used. Although MPN procedures require less time to obtain an estimate of bacterial numbers, isolation and identification of the microbial population is not possible. Alfalfa herbage was treated with ethylene oxide for 12, 24, or 36 h, incubated for 7 days at 37°C with or without addition of a bacterial inoculant, and analyzed for total bacteria by MPN procedures. Microbial growth after inoculation of ethylene oxide-treated herbage indicated that there was insufficient residual ethylene oxide to inhibit subsequent microbial growth. The results also indicated that 24 h was required to adequately sterilize fresh herbage. Thus, ethylene oxide can be used to sterilize wet herbage for use as a substrate for pure cultures of silage bacteria.     

Rapid and simple method for the most-probable-number estimation of arsenic-reducing bacteria.

A rapid and simple most-probable-number (MPN) procedure for the enumeration of dissimilatory arsenic-reducing bacteria (DARB) is presented. The method is based on the specific detection of arsenite, the end product of anaerobic arsenate respiration, by a precipitation reaction with sulfide. After 4 weeks of incubation, the medium for the MPN method is acidified to pH 6 and sulfide is added to a final concentration of about 1 mM. The brightly yellow arsenic trisulfide precipitates immediately and can easily be scored at arsenite concentrations as low as 0.05 mM. Abiotic reduction of arsenate upon sulfide addition, which could yield false positives, apparently produces a soluble As-S intermediate, which does not precipitate until about 1 h after sulfide addition. Using the new MPN method, population estimates of pure cultures of DARB were similar to direct cell counts. MPNs of environmental water and sediment samples yielded DARB numbers between 10(1) and 10(5) cells per ml or gram (dry weight), respectively. Poisoned and sterilized controls showed that potential abiotic reductants in environmental samples did not interfere with the MPN estimates. A major advantage is that the assay can be easily scaled to a microtiter plate format, enabling analysis of large numbers of samples by use of multichannel pipettors. Overall, the MPN method provides a rapid and simple means for estimating population sizes of DARB, a diverse group of organisms for which no comprehensive molecular markers have been developed yet.     

Rapid and Simple Method for the Most-Probable-Number Estimation of Arsenic-Reducing Bacteria

A rapid and simple most-probable-number (MPN) procedure for the enumeration of dissimilatory arsenic-reducing bacteria (DARB) is presented. The method is based on the specific detection of arsenite, the end product of anaerobic arsenate respiration, by a precipitation reaction with sulfide. After 4 weeks of incubation, the medium for the MPN method is acidified to pH 6 and sulfide is added to a final concentration of about 1 mM. The brightly yellow arsenic trisulfide precipitates immediately and can easily be scored at arsenite concentrations as low as 0.05 mM. Abiotic reduction of arsenate upon sulfide addition, which could yield false positives, apparently produces a soluble As-S intermediate, which does not precipitate until about 1 h after sulfide addition. Using the new MPN method, population estimates of pure cultures of DARB were similar to direct cell counts. MPNs of environmental water and sediment samples yielded DARB numbers between 10¹ and 10⁵ cells per ml or gram (dry weight), respectively. Poisoned and sterilized controls showed that potential abiotic reductants in environmental samples did not interfere with the MPN estimates. A major advantage is that the assay can be easily scaled to a microtiter plate format, enabling analysis of large numbers of samples by use of multichannel pipettors. Overall, the MPN method provides a rapid and simple means for estimating population sizes of DARB, a diverse group of organisms for which no comprehensive molecular markers have been developed yet.     

Influences of light and oxygen conditions on photosynthetic bacteria macromolecule degradation: different metabolic pathways

Direct degradation of macromolecules by photosynthetic bacteria (PSB) is important for the industrial application of PSB wastewater treatment. Light and oxygen are the most important parameters in PSB growth. This paper studied the PSB macromolecule degradation process under three different light and oxygen conditions: light-anaerobic, natural light-microaerobic and dark-aerobic. The results showed that under three different light-oxygen conditions, PSB degradation of macromolecules was higher than 90%; the removal ratios of COD, TN, TP, total sugar and protein were also high; and the biomass yield reached nearly 0.5 mg-biomass/mg-COD-removal. Light and oxygen significantly influenced the efficiency. Macromolecules and pollutants removals were higher under oxygen condition than those under light-anaerobic condition. Theoretical analysis showed that under aerobic condition, PSB carried out oxidative phosphorylation, in which pollutants were sufficiently utilized with high mineralization degree. Under light-anaerobic condition, PSB carried out photophosphorylation and fermentation, which led to low pollutants removal efficiency.     

Estimation of Low Numbers of Escherichia coli Bacteriophage by Use of the Most Probable Number Method

The estimation of low numbers of the Escherichia coli bacteriophage was made possible by use of the most probable number (MPN) method. This method is similar to the technique used for counting coliform bacteria. The statistical results were computed by referring to tables. The method makes it possible to record values as low as two particles per 100 ml of sample. The direct plate count and MPN method were found to be in good correlation for T2 bacteriophage and bulk T bacteriophage in samples obtained from a sewage treatment plant and from contaminated seawater.     

A Most Probable Number method (MPN) for the estimation of cell numbers of heterotrophic nitrifying bacteria in soil

A Most Probable Number (MPN) method was developed allowing for the first time estimation of populations of bacteria capable of heterotrophic nitrification. The method was applied to an acidic soil of a coniferous forest exhibiting nitrate production. In this soil nitrate production was unlikely to be catalyzed by autotrophic nitrifiers, since autotrophic ammonia oxidizers never could be detected, and autotrophic nitrite oxidizers were usually not found in appreciable cell numbers. The developed MPN method is based on the demonstration of the presence/absence of nitrite/nitrate produced by heterotrophic nitrifying bacteria during growth in a complex medium (peptone-meat-extract softagar medium) containing low concentrations of agar (0.1%). Both the supply of the growing cultures in MPN test tubes with sufficient oxygen and the presence of low agar concentrations in the medium were found to be favourable for sustainable nitrite/nitrate production. The results demonstrate that in the acidic forest soil the microbial population capable of heterotrophic nitrifcation represents a significant part of the total aerobic heterotrophic population. By applying the developed MPN method, several bacterial strains of different genera not previously described to perform heterotrophic nitrification have been isolated from the soil and have been identified by bacterio-diagnostic tests.     

THE SUITABILITY OF CERTAIN OBLIGATELY ANAEROBIC NONSPOREFORMING ENTERIC BACTERIA, AS PART OF A MORE EXTENDED BACTERIAL ASSOCIATION, AS INDICATORS OF 'FAECAL CONTAMINATION'OF FOODS

SUMMARY: The suitability, as indicators of the faecal contamination of foods, of two types of obligately anaerobic nonsporeforming bacteria which are very numerous in faeces, viz. members of the genera Bacteroides and Bifidibacterium , was tested. For the counting of Bacteroides , Beerens'bile-azide agar (1957) enriched with 10% (v/v) of blood, and incubated in oval cross section tubes, was found useful. Bifidibacterium could be counted very well in Frisell's tomato-azide agar (1951), incubated in the same way . Both media being not too selective, confirmation of representative numbers of colonies was necessary. After microscopical examination, the biochemical study of properties such as catalase reaction, oxygen tolerance, carbohydrate fermentation and nitrate reduction may be required.
The 3 Bacteroides strains tested died off rather rapidly when present in sterile ice cream under conditions where Enterobacteriaceae and faecal streptococci increased in numbers. Accordingly they were never found in considerable numbers in some 25 samples of food which appeared to contain very high numbers of other bacteria of faecal origin. The 8 Bifidibacterium strains investigated appeared more resistant. However, under conditions permitting growth, they increased less than the Enterobacteriaceae and faecal streptococci; and where the latter did not increase but did survive, the Bifidibacterium decreased in numbers. In line with these findings Bifidibacterium was not even found in numbers of the order of 10/g in the 25 samples of food mentioned above. Neither Bacteroides nor Bifidibacterium can therefore be considered suitable as an indicator of the contamination of foods with bacteria of faecal origin and of the subsequent growth of these bacteria therein.     

除草剂二氯喹啉酸对水稻田土壤中微生物种群的影响

对好氧微生物采用平板稀释法,厌氧微生物采用最大或然计数法和滚管法研究土壤中施入0．33、0．67、1．00、1．33、2．00μg·g^-1干土除草剂二氯喹啉酸后对土壤可培养微生物种群数量的影响。结果表明,各种微生物对二氯喹啉酸的反应随其施加浓度的不同而有差异．二氯喹啉酸对水稻田土壤中好氧性细菌、水解发酵细菌、反硝化细菌数量的影响都是短暂的,第33d时均能恢复至接近对照水平,浓度在1．33μg·g^-1干土以下时二氯喹啉酸促进真菌数量增加,高于该浓度时则具有抑制作用．施用各浓度二氯喹啉酸初期,对土壤中放线菌和产甲烷菌有一定程度的抑制效应,但低浓度时抑制效应在培养后期消失．正常土壤施用量的二氯喹啉酸(即0．67μg·g^-1干土)对水田土壤微生物各种群无实质危害级农药。