黄曲霉毒素危害、检测方法及生物降解研究进展

黄曲霉毒素(AF)是由某些真菌产毒菌株产生的次生代谢产物,具有极强的毒性.论文介绍了黄曲霉毒素对畜禽的危害以及薄层色谱(TLC)检测法、高效液相色谱(HPLC)检测法、酶联免疫(ELISA)检测法和放射免疫(RIA)检测法等检测方法,并对黄曲霉毒素生物降解的研究概况做一综述.     

金沙江干热河谷区退化土壤结构的分形特征研究

分形理论是近年来兴起的一种新的研究工具。分析结果表明 :土壤粒径分布的分形维数能客观地反映退化土壤的结构状况和退化程度 ,可作为退化土壤结构评价的一项综合性定量指标。退化土壤的分形维数与土壤颗粒组成和微团聚体组成之间存在着明显的相关性。土壤中 <0 .0 0 1mm粘粒含量越高 ,>0 .2 5 mm团粒含量越低 ,则分形维数越高 ,结构性越差。对于同一土壤退化系列 ,分形维数越高 ,土壤退化越严重。     

三氯乙烯共代谢生物降解研究

采用室内培养试验方法，研究了三氯乙稀(TCE)共代谢对生物降解的影响。结果表明，作为能够支持TCE共代谢的生长基质之一的甲苯的初始浓度对TCE的生物降解影响很大，在TCE对甲苯的物质浓度比为1：23、1：115和1：230的实验中，分别有60％、95．44％和64、3％的TCE被降解了。在第二种浓度比下，TCE和甲苯的降解速率最快，降解程度最为彻底。另外，在TCE和甲苯的降解曲线中观察到了曲线振荡现象，并且两者浓度比越接近于1，其振荡越为严重。     

Remediation of amide pesticide-polluted soils by combined solarization and ozonation treatment

Agriculture has a close relationship with nature, but it can also be the source of negative and permanent environmental effects. The use of pesticides in modern agriculture is a common practice, but their side effects on the environment cannot be disregarded. In this study, we evaluated a combination of solarization and ozonation techniques for the elimination of six amide pesticides (boscalid, chlorantraniliprole, cyflufenamid, fluopyram, napropamide, and propyzamide) in soil. Initial experiments were performed with four different soils to assess the efficiency of this methodology at different soil temperatures and ozone dosages under laboratory conditions, and then a greenhouse pot experiment was conducted under controlled conditions during summer. Fifty days after the onset of the experiments, higher degradation percentages of amide pesticides were observed in ozonized soils than in other treated soils, particularly when ozone was applied at 10 cm soil depth. The results show that the utilization of ozonation, along with solarization, represents a valid method for degrading residues of the studied pesticides and suggest that this combined technology may be a promising tool for remediating pesticide-polluted soils.     

Effect of intermittent heat treatment on crystallinity in wood cellulose

The effect of intermittent heat treatment on cellulose crystallites in wood was studied to evaluate quantitatively the changes of crystallinity induced by intermittent and continuous heating. The changes in crystallinity were found to be strongly affected by the intermittent heat treatment. The increased crystallinity, the width of the crystals, and the piezoelectric properties were the same for the first intermittent heating as for continuous heating. Further intermittent heating for the same time duration and temperature had no effect on the above properties, probably due to the stopping of the thermal reaction during the interval. Our results suggested that intermittent heat treatment has certain critical cooling temperatures that stop the thermal reaction and are closely related to the duration of the interval. Samples once exposed to a certain duration of heat treatment and then cooled need more time, about twice that of the first duration of intermittent heating compared with continuous heating, to reach maximum crystallinity in wood cellulose.     

振荡发酵生产球形细菌纤维素

采用振荡发酵生产球粒形细菌纤维素,以提供外观和口感新颖独特的纤维素产品.结果表明:培养基的碳源浓度、椰子水添加量、装瓶量、振荡速度等对纤维素颗粒的形状、产量影响较大.最佳发酵工艺为:15g/L蔗糖,(NH4)2SO43 g/L,KH2PO43g/L,MgSO4·7H2O 0.2 g/L,酵母粉0.5 g/L,20%(ν/ν)椰子水,20%(ν/ν)菠萝汁,500mL三角瓶装200mL发酵液(液高3.4 cm),初始pH4.5,150 r/min,30℃振荡培养10d.在此条件下,可得到粒形均匀(φ 0.8～1.0 cm)、产量较高(3.15 g/L)的球形细菌纤维素.这种新型纤维素球粒能满足食品工业和消费者多元化的需求.     

不同腐烂程度毛竹蔸微生物变化规律

研究不同腐烂程度毛竹蔸中的微生物菌群,结果发现细菌对数值最低为5.477,最高为7.380;真菌对数值最低为5.301,最高为6.903;放线菌对数值最低为5.740,最高为7.000;纤维素降解菌对数值最低为4.301,最高为6.477;木质素降解菌最低为4.415,最高为6.799。毛竹蔸腐烂过程中,前期各菌增长较快;中期细菌、真菌、放线菌对数值不断变化;后期菌对数值都较高;各菌之间存在着一定的协助和竞争。了解竹林砍伐前期的竹蔸腐烂规律,可为砍伐后的竹蔸降解提供参考,同时为竹蔸微生物在种级单位上的分离提供依据。     

大豆油不同添加水平对瘤胃体外发酵和产气的影响

本试验通过体外培养,研究在精粗比为30:70(偏粗型)日粮类型条件下,不同大豆油添加水平对产气量、甲烷产量、pH值和纤维降解率的影响.结果表明:随着大豆油添加水平的提高,产气量和甲烷产量逐渐降低,且各添加组显著低于对照组;pH值随着培养时间的延长,各添加水平在不同培养时间点与对照组相比均上升,其中添加量为4%和6%与对照组相比差异显著(P<0.05),添加量为8%时,与对照组相比差异极显著(P<0.01);培养24 h后.纤维降解率的抑制潜力8%水平最大,与对照组相比差异极显著(P<0.01),其次是6%的添加水平.与对照组相比差异显著(P<0.05).而2%和4%添加水平对纤维降解率的抑制程度与对照组相比差异不显著(P>0.05).通过产气量、pH值和纤维降解率综合考察大豆油对瘤胃体外发酵和产气的影响,本试验得出大豆油的最适添加量为4%.     

和稀盐酸联合催化下的水解动力学研究

以微晶纤维素为原料,在1 g/L的FeCl3存在下和2%的盐酸溶液体系中进行水解,根据水解属于串联反应的特点,研究了微晶纤维素在H+和Fe3+共同作用下的水解动力学规律。研究采用目标物产率与模型函数值残差(S)为最小确定模型函数,对实验数据进行了处理。结果表明:H+和Fe3+共同作用能显著降低纤维素水解和葡萄糖降解的活化能。其中,纤维素水解成为葡萄糖的活化能为81.70 kJ/mol,葡萄糖降解成为小分子的活化能为43.85 kJ/mol,在温度为130、140和150℃时,纤维素水解速率常数分别为0.041 4、0.073 2和0.115 3 h-1,相应温度下葡萄糖降解速率常数分别为0.205 3、0.242 4和0.356 5 h-1。