Toxicity assessment of nickel using Aspergillus niger and its removal from an industrial effluent

Chemical analysis of electroplating effluent revealed the presence of very high concentrations of nickel (393 ppm) in the effluent. Bioassay was carried out to test the toxicity of nickel chloride to Aspergillus niger. In contrast to 50% conidial inhibition at 1.7 mM nickel, hyphal extension was affected even at a lower concentration (0.4 mM), suggesting that hyphae are more sensitive than conidia to nickel. An increase in nickel concentration resulted in a proportionate decrease in the hyphal extension. Nickel (II)-resistant mutants of A. niger M1, M2, and M3, were obtained using direct selection, stepwise adaptation, and ultraviolet mutation techniques. Biosorption of Ni (II) by the mutant M3 was 50% more than that of its parent strain.     

土壤重金属污染生物修复技术研究进展

从生物修复的概念和重金属污染土壤的方式出发,对重金属污染土壤植物修复和微生物修复两个方面的一般原理、方法和研究动态进行了综述,指出:重金属污染土壤生物修复基本上处于试验开发阶段,其今后研究的重点为探索超积累植物修复的机理,开发土壤改良剂和生物吸附剂以增加效益,超积累植物生物学性状的改善和微生物基因工程菌的构建,以生物修复为核心的联合修复作用的发挥及生物修复指标体系的建立.可以预料,重金属污染土壤生物修复具有很大的发展前景.     

黑曲霉对Cu~(2+)生物吸附的研究

利用常规微生物资源黑曲霉(Aspergillus niger),对重金属铜进行生物吸附,研究了转速、pH值、吸附时间等影响因素对黑曲霉生物吸附Cu2+的影响.实验结果表明,当转速为100r/min时,黑曲霉对Cu2+的生物吸附量最大,为6.688mg/L;当pH为5时,黑曲霉对Cu2+的生物吸附量达到最大,为6.713mg/L;前30min ,黑曲霉对Cu2+的生物吸附非常迅速,吸附效率由0增加到18.95% ,30～60min,黑曲霉对Cu2+的生物吸附缓慢增加,60min后吸附达到稳定.     

土壤硒污染的生物修复技术

硒是一种较特殊的微量元素，人和动物缺硒和硒中毒之间的范围很窄，土壤硒污染能对当地的人和动物产生重大伤害。采用传统的土壤污染治理方法，成本高，效果差，而近年来兴起的生物修复技术是治理土壤硒污染的既有效又经济的方法。     

Biodegradation of Pyridine and Pyridine Derivatives by Soil and Subsurface Microorganisms

Abstract

Large amounts of aromatic compounds are produced by various industries and two thirds of these are heterocyclic chemicals. Compared with the extensive information available on microbial degradation of homocyclic aromatic compounds, relatively little is known on the transformation and biodegradation of heterocyclic chemicals in soil. Recent concerns about the persistence of hazardous pollutants have led to a renewed interest in the biodegradation of heterocyclic compounds. Hence, we investigated the microbial degradation of pyridine and some of its alkylated derivatives under aerobic and anaerobic conditions in groundwater, subsurface sediment, and soil. Results of the investigation revealed that these compounds were degraded predominantly under aerobic conditions and, to a lesser extent, under anaerobic conditions, with nitrate or sulfate serving as electron acceptors. In groundwater polluted with various pyridine derivatives, biodegradation was limited by the absence of oxygen. Therefore, we conclude that, under appropriate conditions, bioremediation is a potentially feasible method for the clean-up of environments contaminated with heterocyclic chemicals and, in particular, pyridine derivatives.     

A simple method for quantifying activity and survival of microorganisms involved in bioremediation processes

We have developed a substrate-induced growth response (SIGR) method for quantifying activity and population dynamics of microorganisms involved in bioremediation processes in soil and bioreactors. The biomass of organisms that can mineralize a given chemical can be estimated based on the concentration of that chemical needed to induce the growth of the standing population. Estimates of population size are obtained by using nonlinear regression techniques to fit a simple model of microbial population dynamics to biodegradation curves. Using this approach we obtain estimates of values for parameters such as initial population size and growth rate of organisms carrying out biodegradative processes. Our approach was validated by comparing model parameter estimates with independent estimates of the same parameters from the same bioremediation systems. Examples studied include pentachlorophenol degraders introduced into soil and 2,4-dinitrophenol degrading organisms in a bioreactor.