人工湿地系统微生物去除污染物的研究进展

人工湿地污水处理系统具有净化效果显著、建设和运行费用低廉、管理简便等优点,近年来越来越受到人们的重视。人工湿地是利用介质、植物和微生物构成的复合系统来处理污水。微生物在人工湿地系统净化污水过程中发挥着重要作用。介绍了人工湿地系统中微生物去除污染物的研究进展,重点讨论了人工湿地对污染物和特殊有机污染物的去除以及系统基质中微生物的种群和活性等内容,并结合我国研究现状展望了该领域的研究前景。人工湿地系统微生物对污染物去除将成为人工湿地生态系统服务功能评价、人工湿地生态系统健康与稳定的诊断的重要组成部分。     

聚合物驱采出水中聚丙烯酰胺的微生物联合降解作用研究

通过对2株细菌的培养降解实验研究聚丙烯酰胺(hydrolyzed polyacrylamide,HPAM)降解菌对水环境下聚丙烯酰胺的降解作用,讨论协同降解机理。2株降解聚丙烯酰胺的菌株假单胞菌CJ419、枯草芽孢杆菌FA16在初始30℃废水样品上培养,定期测量细菌生物量和HPAM降解率。培养30 d后CJ419和FA16对聚合物的降解率最大值分别达到30.4%和25%,而以1∶1比例的混合菌降解率最大值达到80.3%。对2株菌胞外各组分研究表明:混合菌降解HPAM的机理主要由胞外降解酶系水解聚合物侧链基团导致HPAM降解为小分子物质,同时生长过程中降解菌还会释放非蛋白还原性物质引发氧化反应共同参与HPAM降解。     

腐熟蓝藻与厌氧污泥混合厌氧发酵特性

采用批次小试实验对不同腐熟程度的蓝藻进行厌氧发酵产沼气实验研究。结果表明,新鲜蓝藻在30-35℃时腐熟7 d后,可在35℃的厌氧温度下获得最高的产气速率和246 mL/g COD的产气量,产气潜力为354 mL/g（VS）。厌氧反应15 d后,累计产气量、COD和VFA浓度趋于稳定。淀粉酶和脱氢酶的活性在厌氧反应初期受到抑制,蛋白酶活性和辅酶F420浓度在厌氧系统中逐渐增加,分别在第6天达到27.66μmol/（g VS·min）和第15天达到0.62μmol/g（VS）。15-18d是腐熟蓝藻适宜的中温厌氧发酵时间,少于以新鲜蓝藻为基质的厌氧消化时间。蓝藻腐熟过程促进了厌氧反应,腐熟7 d的蓝藻厌氧系统具有更高的微生物活性和产甲烷能力。     

Dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities

The dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities were investigated. The results revealed that carbendazim dissipation was little affected by chloramphenicol, whereas chloramphenicol dissipation was found to be retarded significantly by the presence of carbendazim. The inhibitory effect of carbendazim on the fungal:bacterial ratios was increased by the presence of chloramphenicol, and the inhibitory effect of chloramphenicol on neutral phosphatase was increased by the presence of carbendazim. Carbendazim increased soil catalase and urease activities, but this increase was partially diminished by the presence of chloramphenicol. Little interaction was observed between carbendazim and chloramphenicol with regard to their influence on soil invertase. The results obtained in this study suggest that combinations of fungicides and antibiotics may alter the compounds’ individual behaviors in soil and their effects on soil enzymes.     

PVA降解混合菌系生长和产酶的营养条件分析

研究碳源、氮源以及不同金属离子对PVA降解混合菌系生长和产酶的影响。结果表明,混合菌系生长过程中无机氮源优于有机氮源;补充碳源可促进混合菌系的生长,但酶活比不添加时稍有降低。金属离子对酶活影响的正交实验表明Mg2＋浓度影响最大,其次是Fe2＋和K＋浓度,Ca2＋、Mn2＋、Zn2＋和Cu2＋浓度影响较小;最佳浓度分别为Mg2＋0.05 g/L、Fe2＋0.04 g/L、K＋2 g/L和Ca2＋0.05 g/L。     

Effect of some herbicides on activities of microorganisms and enzymes in soil

Abstract

Laboratory tests were conducted with eight herbicides, atrazine, butylate, ethalfluralin, imazethapyr, linuron, metolachlor, metribuzin and trifluralin, applied to a loamy sand at rate of 10 μg/g to determine if these materials caused any serious effects on microbial and enzymatic activities related to soil fertility. Some herbicides showed an effect on bacteria and fungi for the first week of incubation, but, subsequently, the populations returned to levels similar to those obtained in the controls. After several herbicide treatments there appeared to cause a slight depression of nitrification. Sulfur oxidation was better than that obtained with untreated soil in all treatments. Oxygen consumption was increased significantly after 96 hr incubation with atrazine. The soil dehydrogenase and amylase activities were inhibited by ethalfluralin treatment respectively for 1 wk and 1 day, and p‐nitrophenol liberation was inhibited for 2 hrs by all herbicide treatments. Results indicated that the herbicidal treatments at the level tested were not drastic enough to be considered deleterious to soil microbial and enzymatic activities which are important to soil fertility.     

Effect of tracer dyes on initial deposits and persistence of bacillus thuringiensis subsp. kurstaki toxin after application of two commercial formulations onto spruce trees

Abstract

The effect of two tracer dyes [Erio Acid Red (EAR) and Acid Black 48 (AB‐48)] on initial deposits and persistence of Bacillus thuringiensis subsp. kurstaki (Btk) toxin (delta‐endotoxin) was studied after spraying two commercial formulations, Foray® 48B and Foray® 76B, over potted white spruce [Picea glauca (Moench) Voss] seedlings, at a dosage rate of 30 billion international units (BIU) per ha. Spray was applied using a spinning disc atomizer calibrated to deliver droplet sizes similar to those utilized in ultra‐low‐volume (ULV) treatments in operational insect control programs. The sprayed seedlings were left outdoors at the Sault Ste. Marie laboratory for 18 days under natural conditions of sunlight, wind and rainfall. Initial deposits and persistence of delta‐endotoxin protein in spruce foliage were determined by immunoassay [enzyme linked immunosorbent assay (ELISA)] quantification of the delta‐endotoxin. The total protein (inactive plus active) and delta‐endotoxin (active protein) concentrations in the two formulations were determined by a gravimetric procedure and by ELISA respectively.

The initial deposit levels of the toxin on foliage were not markedly affected by the addition of either of the two tracer dyes, and showed only a narrow range of 1521 to 1625 ng/g foliage (fresh weight) for Foray 48B, and 1789 to 2056 ng/g for Foray 76B. However, the persistence of the toxin was significantly influenced by the presence of the dyes. The toxin persisted in foliage only for 7 d post‐spray When the EAR dye was added to Foray 48B, compared to 10 d when no dye was added. The average half‐life (DT₅₀) of disappearance was 17.4 h for Foray 48B with EAR, and 20.9 h when no dye was present. In contrast, the situation was reversed in Foray 76B, since the duration of persistence was 10 d when EAR was added to Foray 76B, compared to 7 d when no dye was added. The average DT₅₀ was 27.9 h for Foray 76B with EAR, and 22.2 h without the dye. Persistence was the longest (14 d) when the AB‐48 dye was added to Foray 76B, and the DT₅₀ was 44.9 h.     

Progress in the genetic manipulation of crops aimed at changing starch structure and increasing starch accumulation

The starch content and its composition have important consequences for the yield of the harvested crop and the materials extracted from it. The functional properties of the foods or other processed materials derived from these crops are also affected by the structure and composition of the starch. Recently, genetic engineering has been used to produce plants with an elevated starch content, achieved by transforming the plant with a mutated bacterial gene coding for an ADPglucose pyrophosphorylase that is active in the presence of metabolites which inhibit the plant enzyme. Besides the practical implications of these results, this experiment provided direct evidence for the regulatory role of the ADPglucose pyrophosphorylase in starch synthesis. Other bacterial enzymes, such as glycogen synthase and branching enzyme, could be introduced in order to modify starch structure. However, a more elegant (but longer-term) approach would be to learn enough about the structure-function relationships of the plant enzymes so that the product of their action could be changed. To achieve this objective, much more will have to be learned about the enzymes involved in the biosynthesis of starch than is presently known. Here, the basic properties of starch and the current research approaches to understanding its biosynthesis are described, together with a perspective of how genetic manipulation of starch structure may be achieved.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

Purification and characterization of extracellular poly(3-hydroxybutyrate) depolymerases

Five extracellular PHB depolymerases of bacteria isolated from various sources were purified to electrophoretic homogeneity and compared with known extracellular PHB depolymerase fromAlcaligenes faecalis T1. The molecular mass of these enzymes were all around 40–50 kDa. Nonionic detergent, diisopropylfluorophosphate and dithiothreitol inhibited the PHB depolymerase activity of all these enzymes. Trypsin abolished PHB depolymerase activity, but not theD-3-hydroxybutyric acid dimer hydrolase activity of all the enzymes. These results showed that the basic properties of these PHB depolymerases resemble those of theA. faecalis T1 enzyme. Analysis ofN-terminal amino acid sequence of the purified enzymes revealed that these enzymes includingA. faecalis T1 enzyme fall into three groups.     

The Role Played by Acetyl Group Distribution Patterns in Substituted Starch Toward Enzymatic De-acetylation and Chain Fragmentation

The nature and distribution of the acetylated groups were evaluated by ¹³C-NMR and ¹H-NMR. The starch substrate with a DS of 1.5 comprises only two patterns: -(14)-d-glucopyranose and 2,3,6-tri-O-acetyl--(14)-d-glucopyranose. The starch with a DS of 3.0 also comprises two patterns: 2,3,4,6-tetra-O-acetyl--(14)-d-glucopyranose and 2,3,6-tri-O-acetyl--(14)-d-glucopyranose; whereas starch (DS = 1.9) contains 4 patterns: 2,3,6-tri-O-acetyl--(14)-d-glucopyranose, 2,3,4,6-tetra-O-acetyl--(14)-d-glucopyranose terminal, 2,6-di-O-acetyl--(14)-d-glucopyranose, and 3,6-di-O-acetyl--(14)-d-glucopyranose. Using esterase from Viscozyme, it has been possible to hydrolyze up to 7% of the DS 3.0 starch. An -amylase (Fungamyl 800) was then added to these acetylesterases. With a 2.4 FAU/mL fraction of -amylase and 2.4 U/mL from the Viscozyme's acetylesterase, 28% of the acetylated end groups were hydrolyzed for the starch substrates with DS 3.0. Moreover, a synergic action between -amylase and acetylesterase was noticed, allowing fragmentation of 32% for DS 1.5, 30% for DS 1.9, and 11% for DS 3.0.