Properties of mercuric reductase from a HgCl2-resistant fungus

Mercuric reductase is detected in Cephalosporium tabacinum F2.The enzyme, which is an intracellular one,catalyzes the reduction of mercuric ions to elemental mercury,which requires NADH as an electron donor and added sulfhydryl compound.The optimum temperature and pH of the enzymatic reaction are 30℃ and 7.0- 8. 0,respectively.The enzyme activity is stable in the range of 25- 30℃ for 40min,and stable at pH 7. 0 for 2 hours. Metal ions such as Ag⁺ ,CO²⁺), Cu²⁺,Zh²⁺, Mn²⁺,Ni²⁺ show different degrees of inhibitory effect on the enzyme activity,other compounds such as phenylmercury acetate and potassium ferricyanide also partially inhibit the enzyme activity.     

Effects of copper, manganese and pH on the growth and several enzyme activities of mycorrhizal fungus Cenococcum geophilum Fr.

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电子产品常用有机涂层防霉特性研究

对于电子产品中不防霉的材料和零部件,为防止其长霉影响整个产品,采用防霉涂层和喷涂保护剂是最经济有效的措施.通过对1280件电子产品(或主要组成材料和工艺试片)霉菌试验结果的统计分析,总结出各种电子产品常用材料,特别是几种常用有机涂层的防霉特性.     

真菌(Aspergillus sp.)吸附Cu2+的研究

利用真菌Aspergillus sp.制备生物吸附剂,吸附重金属离子铜,实验分析了影响吸附率和吸附量的因素,结果表明,优化条件下,30℃, pH值5.0,起始Cu2+浓度50mg/L,摇床转速150r/min,经1mol/L NaOH预处理的吸附剂用量为5g/L,吸附时间45min,该吸附剂对Cu2+的吸附率达到92.22%.通过细胞显微观察和X-射线光电子能谱技术手段推断该菌细胞壁是Cu2+ 吸附的主要部位.     

Colonial recognition of fungus in the fungus-growing ant Acromyrmex subterraneus subterraneus (Hymenoptera: Formicidae)

Summary. Leaf cutting ants live in symbiosis with a basidiomycete fungus that is exploited as a source of nutrients for the ant larvae. Tests of fungus transport demonstrated that Acromyrmex subterraneus subterraneus workers discriminate concolonial fungus from alien fungus, and rejected the latter. Larvae and pupae of the ant were used as controls. Chemical analysis of the fungus revealed a great similarity between its hydrocarbon profile and that found on the ant brood. Experiments with lures showed that chemical extracts from the fungus are responsible for this discrimination process. Moreover, the presence of brood inside the fungus seemed to be important for discrimination of the fungus by workers. Resident workers accepted concolonial broodless fungus less than concolonial fungus inoculated with brood odor. Fungus seems to acquire colonial odor passively, simply by contact with the brood. The impact of fungus volume present in the nest on closure of the colony is discussed. We show here for the first time the importance of a symbiotic vegetal organism in colonial recognition in social insects. Received 14 April 2000; accepted 29 September 2000     

棘孢曲霉(Aspergillus aculeatus)对Pb~(2+)和Cd~(2+)的吸附特征

为了研究棘孢曲霉(Aspergillus aculeatus)对溶液中Pb~(2+)和Cd~(2+)吸附过程的特征,分别从动力学、热力学和吸附等温线三方面进行了实验,同时还研究了pH、温度、时间、重金属离子起始浓度和吸附剂用量对吸附过程的影响。等温吸附过程可以用Langmuir方程来描述。在实验设定条件下,棘孢曲霉对Pb~(2+)和Cd~(2+)最大吸附量分别为71.2 mg/g和59.8 mg/g;动力学实验数据很好的符合二级动力学方程,吸附达到平衡的时间为3 h;热力学实验数据显示该吸附过程为自发的、吸热的过程。     

白腐真菌木质素降解酶的反应器发酵

为了获得更高的白腐真菌木质素降解酶的产量和相应的控制策略,应用5L搅拌罐生物反应器对氮限制下(C/N=56/2.2)P.chrysosporium产木质素降解酶进行了放大研究.结果表明,在分批发酵试验中,锰过氧化物酶(MnP)和漆酶(Lac)分别在培养第6d和第7d达到峰值,其酶活随时间的变化规律与摇瓶试验基本相同;而采用氮限制液体培养基进行补料没有获得更高的酶活,因此,可以得出采用发酵液体培养基作为补料液不利于白腐真菌持续产酶.另外,在分批发酵和分批补料发酵过程中,均发现体系pH值变化与白腐真菌生长和次生代谢产酶具有较好的相关性,当白腐真菌进入次生代谢阶段开始产酶时,体系pH值开始下降,随着发酵后期酶活的降低,pH值下降的幅度也逐渐变小,当体系酶活接近为0.0U/L时,pH值基本不再变化.因此,在实际发酵过程中,可以依据体系pH的变化间接了解白腐真菌的生长和产酶情况,而分批补料策略还有待于进一步研究.     

真菌和细菌对染料的吸附脱色及再生能力的研究

进行了真菌和细菌共培养对染料的吸附脱色和吸附脱色能力再生的研究。结果表明，青霉菌G－1首先对偶氮染料S－119、蒽醌染料艳紫KN－B（C．I．Reactive violet 22）水溶液中染料进行快速吸附去除，菌丝对同种染料的吸附速度随菌丝培养液中葡萄糖浓度的增加而加快，吸附染料的G－1菌丝在与细菌的共培养中完成对染料的脱色降解，脱色速度受培养液中葡萄和氮源浓度影响较大，从吸附速率和完全脱色时间综合评价，以葡萄糖浓度为5g/L、酒石酸铵为20mmol/L的培养基中培养的菌丝对染料的吸附脱色效果最好，吸附在菌丝上的艳紫KN－B脱色后菌丝吸附脱色能力得到再生，菌丝对100mg/L的艳紫KN－B染料水溶液可重复处理4次。青霉菌G－1对酸性染料废水处理3h，色度去除率为75．9％，吸附染料的菌丝在与细菌共培养中完成对染料的脱色，对试验所用染料废水，菌丝的处理能力获得1次再生。     

漂白废水白腐菌脱色的条件

碳源、氮源、Mn^2 浓度及pH值对F7菌漂白废水脱色有较大的影响，最佳培养基组成为：ρ（葡萄糖）10g/L，ρ（NH4Cl）0．13g/L，ρ（Mn^2 )20mg/L，随葡萄糖和NH4Cl添国量的增加，菌体生物量增加，但高浓度的NH4Cl对F7菌脱色有抑制作用，F7菌适宜生长pH值为4－5，适宜脱色pHwfhgo 3-6,最适脱色pH值为5．0另外，经脱色处理的漂白废水的毒性明显下降。     

白腐菌对3种含氯二(噁)(口英)类物质的降解作用

探讨了白腐菌射脉侧菌Phlebia radiateI-5-6对3种含氯量不同的二类物质———二苯并呋喃(DF)、2,7-二氯二苯并二(2,7-diCDD)和八氯二苯并呋喃(OCDF)的降解情况,并研究了不同培养条件对二降解的影响.在液体混合培养基中,在培养期内P.radiataI-5-6对3种二类物质的降解量分别为:DF>2,7-diCDD>OCDF;在培养的初始阶段,白腐菌对珠江江水/CEH漂白废水的加入需要一个适应期,然后开始降解这些污染物质.实验表明,在江水/CEH漂白废水处于一定浓度时,污染底物有更大的降解量;选择适当的培养基,可影响白腐菌对二类污染物的降解量.图3表3参17