海岸盐沼湿地细菌抗真菌活性研究

为了开发对植物病原真菌生长有抑制作用的药源微生物,本实验采用平板稀释法从江苏大丰盐沼湿地土壤中分离微生物,并通过菌丝块法检测这些微生物代谢产物对5种植物病原真菌生长的抑制活性,进而利用柱层析分析其活性成分;结果共分离得到235株细菌,其中好氧细菌92株,厌氧细菌143株;体外活性测试结果显示有65株至少对1种测试植物病原真菌的抑制率在30%以上,其中好氧菌39株,厌氧菌26株。从好氧和厌氧菌株中分别选取3株和1株具有不同抗菌类型的菌株进行大批发酵,用不同的方法对发酵液吸附,分离和纯化,获得抗真菌活性组分。可见,海岸盐沼湿地土壤中蕴涵着大量的细菌种群,约有28%的细菌菌株能够产生抗真菌活性物质,其中Y6、Y156和Y96的抗真菌活性物质极性较大,值得进一步开发。     

新疆红雁池鱼场非洲鲫鱼传染病病原学研究初报

红雁池鱼场利用电场冷却电机回流水饲养非洲鲫鱼。１９８２～１９８３年分３批从北京小唐山温泉鱼场引进非洲鲫鱼，进场不久即大批死亡，死亡率由１８．３７％到几乎全群覆灭，造成很大的经济损失．经采样进行细菌分离与鉴定并对菌株作药敏试验，同时将病鱼组织磨碎，匀浆后进行差速离心和梯度离心沉淀，点样用磷钨酸和醋酸氧铀分别染色作电镜观察。其结果为；电镜检查未发现病毒，细菌学检查分离出８株细菌。分离出的细菌以气单胞菌属菌为主（８株菌中、气单胞属菌占６株），因此定名为气单胞菌感染复合症（ＡｅｒｏｍｏｎａｄＭｉｘｅｄＩｎｆｅｃｔｉｖｅ　Ｃｏｍｐｌｅｘ）。分离上述菌株对小白鼠有较强致病力，鉴于国外文献报道气单胞菌属偶能引起人传染性胃肠炎，故本病可能为人鱼共患病，特此报道．警惕注意。     

活性乳酸菌饮料中发酵乳酸度与柠檬酸用量关系的研究

为了研究活性乳酸菌饮料中发酵乳酸度与柠檬酸用量的关系,本实验首先对影响口味的各因素(糖量、柠檬酸量、发酵乳酸度)最适范围进行了确定,然后通过三因素三水平选出最佳配比,最后以最佳配比的酸度为标准,在加糖量为5.5%时,测得了不同发酵乳酸度下所需柠檬酸的量。结果表明:发酵乳酸度与柠檬酸用量可以作出一条线形曲线。     

日粮添加豆油和胡麻油对肉牛瘤胃发酵及主要微生物数量的影响

 【目的】评价日粮添加植物油对瘤胃发酵和瘤胃微生物区系的影响。【方法】采用3×3拉丁方设计，用3头装有永久性瘤胃瘘管的杂交肉牛研究不添加油脂（对照组）、添加4％豆油（豆油组）或4％胡麻油（胡麻油组）对瘤胃pH值、NH3-N浓度、VFA以及瘤胃细菌和原虫的影响。3组日粮精粗比均为35﹕65，每期试验为21d，共3期。【结果】添加油脂对瘤胃内pH值没有影响(P＞0.05)；对照组和胡麻油组瘤胃NH3-N浓度显著高于豆油组(P＜0.05)；与对照组相比，豆油组和胡麻油组显著降低了瘤胃乙酸、丙酸、丁酸、总挥发性酸浓度以及总细菌、蛋白分解菌、纤维分解菌及原虫的数量(P＜0.05)，但对乙酸与丙酸比例以及淀粉分解菌数量两个指标组间无显著差异(P＞0.05)。对照组、豆油组和胡麻油组纤维分解菌和原虫的数量依次分别为6.79×108、5.71×108、5.92×108；10.67×104、7.11×104、9.56×104 CFU•ml-1；两个加油组显著降低了瘤胃纤维分解菌和原虫数(P＜0.05)。【结论】日粮添加4％豆油和胡麻油对瘤胃发酵及主要微生物都有一定的抑制效应，但二者抑制效应大小无显著差异。     

硫酸盐还原菌的分离与生态特点研究

采用S培养基进行富集培养的方法对硫酸盐还原菌(SRB)进行了分离与鉴定。实验通过对SRB的生理和生化特性的了解,结合其生存条件和存在状态进行研究,得出主要的环境因素中pH值和温度对SRB的腐蚀作用的影响关系,并提出采用合适的环境因素来更好的控制SRB的生长代谢活动,得出有效的防治措施来控制硫酸盐还原菌引起的腐蚀,延长有关设备的正常使用寿命。     

Effect of Bacillus subtilis on granite weathering: A laboratory experiment

We performed a comparative experiment to investigate: (1) how the ubiquitous soil bacterium Bacillus subtilis weathers granite; and (2) which granite-forming minerals weather more rapidly via biological processes. Batch system experiments (granite specimen in a 500 ml solution including NaCl, glucose, yeast extract and bacteria B. subtilis at 27 °C) were carried out for 30 days. Granite surfaces were observed by SEM before and after the experiment. B. subtilis had a strong influence on granite weathering by forming pits. There were 2.4 times as many pits and micropores were 2.3 times wider in granite exposed to B. subtilis when compared with bacteria-free samples. B. subtilis appear to preferentially select an optimum place to adhere to the mineral and dissolve essential elements from the mineral to live. Plagioclase was more vulnerable to bacterial weathering than biotite among the granite composing minerals.     

The impact of protozoa on the availability of bacterial nitrogen to plants

Summary Microbial N from ¹⁵N-labelled bacterial biomass was investigated in a microcosm experiment, in order to determine its availability to wheat plants. Sterilized soil was inoculated with either bacteria (Pseudomonas aeruginosa alone or with a suspension of a natural bacterial population from the soil) or bacteria and protozoa to examine the impact of protozoa. Plant biomass, plant N, soil inorganic N and bacterial and protozoan numbers were determined after 14 and 35 days of incubation. The protozoa reduced bacterial numbers in soil by a factor of 8, and higher contents of soil inorganic N were found in their presence. Plant uptake of N increased by 20010 in the presence of protozoa. Even though the total plant biomass production was not affected, the shoot: root ratios increased in the presence of protozoa, which is considered to indicate an improved plant nutrient supply. The presence of protozoa resulted in a 65010 increase in mineralization and uptake of bacterial ¹⁵N by plants. This effect was more pronounced than the protozoan effect on N derived from soil organic matter. It is concluded that grazing by protozoa strongly stimulates the mineralization and turnover of bacterial N. The mineralization of soil organic N was also shown to be promoted by protozoa.Communication No. 9 of the Dutch Programme on Soil Ecology of Arable Farming Systems     

Growth and interactions of arbuscular mycorrhizal fungi in soils from limestone and acid rock habitats

Arbuscular mycorrhizal (AM) development in different soil types, and the influence of AM fungal hyphae on their original soil were investigated. Plantago lanceolata, which can grow in soils of a very wide pH range, was grown in two closely related limestone soils and an acid soil from rock habitats. Plants were colonised by the indigenous AM fungal community. The use of compartmented systems allowed us to compare soil with and without mycorrhizal hyphae. Root colonisation of P. lanceolata was markedly higher in the limestone soils (30-60%) than in the acid soil (5-20%), both in the original habitat and in the experimental study. Growth of extraradical AM fungal hyphae was detected in the limestone soils, but not in the acid soil, using the signature fatty acid 16:1ω5 as biomass indicator. Analysis of signature fatty acids demonstrated an increased microbial biomass in the presence of AM fungal hyphae as judged for example from an increased amount of NLFA 16:0 with 30 nmol g⁻¹ in one of the limestone soils. Bacterial activity, but not soil phosphatase activity, was increased by around 25% in the presence of mycorrhizal hyphae in the first harvest of limestone soils. AM fungal hyphae can thus stimulate microorganisms. However, no effect of AM hyphae was observed on the soil pH or organic matter content in the limestone soils and the available P was not depleted.     

百草枯对土壤微生物影响的研究

研究了5种不同浓度百草枯对土壤微生物种群数量及土壤中细菌、放线菌和真菌生长速率的影响。结果表明,百草枯对土壤微生物的种群数量及土壤细菌、放线菌和真菌生长速率均具有一定的抑制作用,且随药剂浓度升高逐渐增强。加药后2～7d,对细菌种群抑制率为13.3%～100%,抑菌圈直径达0.07～0.93cm;对放线菌种群抑制率为8.6%～100%,抑菌圈直径达0～3.00cm;对真菌种群抑制率为7.6%～100%,生长速率的抑制率达1.4%～77.3%。抑制作用随加药时间延长又逐渐减弱。     

Changes in the succession and diversity of protozoan and microbial populations in soil spiked with a range of copper concentrations

We studied microbial and protozoan activity, diversity and abundance as affected by Cu²⁺ amendments ranging from 0 to 1000 μg g⁻¹ over a 70-day period. At the end of the experiment the microbial population size, as indicated by substrate-induced respiration, had normalized for all Cu²⁺ concentrations, but 1000 μg g⁻¹. Protozoan abundance was negatively affected by Cu²⁺, although, only in the first few weeks. A more detailed analysis of the individual components that make up the microbial and micro-faunal populations (phospholipid fatty acid (PLFA) profile and protozoan morphotypes), however, yielded a somewhat more complex picture. For the three highest Cu²⁺ amendments (160, 400 and 1000 μg g⁻¹), there still was a significant reduction in number of differentiable protozoan morphotypes. The bacterial PLFA pattern suggested a shift from Gram-negative towards Gram-positive bacteria for the high amendments, a process where protozoan grazing most likely played a significant role. The ratio of the trans/cis isomers of the 16:1ω7 fatty acid indicated that Cu²⁺, even at low and medium concentrations, induced physiological changes in the microbial population. The relatively slight changes in total microbial and micro-faunal abundance and activity, also at the highest Cu²⁺ concentrations, probably reflected the ability of the community to compensate for loss of taxa by functional substitution.