东寨港红树林湿地土壤因子与酶活性的关系

[目的] 红树林是热带、亚热带典型的海岸带湿地生态系统。分析不同植物群落条件下红树林湿地的土壤活性有机碳组成、土壤酶活性现状以及两者间的相互作用,进而预测东寨港红树林片区的生态结构和功能发展趋势,为东寨港红树林湿地的生态恢复与保护提供科学依据。[方法] 通过实地采样,对9种红树植物群落类型〔红海榄(Type 1)、白骨壤(Type 2)、角果木(Type 3)、海莲+角果木(Type 4)、桐花树+海莲+秋茄(Type 5)、海莲+榄李+桐花树(Type 6)、秋茄+海莲+榄李(Type 7)、海莲+无瓣海桑+桐花树+秋茄(Type 8)、海莲+无瓣海桑(Type 9)〕的土壤酶活性、土壤活性有机碳组分含量和理化性质进行化验分析。[结果] ①该区表层土壤有机碳介于6.57~74.87 g/kg之间,在不同群落类型间以Type 7群落显著最高,Type 1群落低至6.57 g/kg。②各群落类型湿地表层土壤酶活性变化规律为：脲酶＞磷酸酶＞过氧化氢酶＞蔗糖酶,其中脲酶以Type 8群落最高,显著高于Type 1—6群落;磷酸酶以Type 8群落最高,显著高于Type 1—3群落;过氧化氢酶以Type 5最高,显著高于其余群落(Type 6和Type 7除外);蔗糖酶以Type 9群落最高,显著高于Type 2,Type 5和Type 8群落。③土壤脲酶、磷酸酶和过氧化氢酶与土壤活性有机碳各组分含量呈显著及极显著正相关;土壤脲酶、磷酸酶与土壤pH值呈极显著负相关,与全氮、全磷呈极显著正相关;土壤过氧化氢酶与全氮、全磷呈极显著正相关;土壤蔗糖酶与全氮、全磷呈显著正相关。④冗余分析结果显示：土壤轻组有机碳、土壤总有机碳、土壤颗粒有机碳和土壤微生物生物量碳是影响东寨港红树林植物群落土壤酶活性的主要因子。[结论] 土壤酶活性与多种土壤活性有机碳组分呈紧密正相关,因此可用土壤酶活来表征东寨港红树林湿地土壤碳库活跃程度。     

微生物代谢组学研究方法

代谢组学是后基因纰时代新兴的一种研究生物样品中所有小分子代谢物的技术,是系统生物学的有机组成部分,并在近年来取得很大进展.该文就微生物代谢组学研究中有关样品制备、代谢产物分析鉴定和数据分析等涉及的主要方法进行了概述,并用一些典型实例介绍微生物代谢组学的应用,对微生物代谢组学研究中潜在的问题和未来发展趋势进行了讨论.     

葡萄糖氧化酶与乳酸菌联合应用对肉鸡肠道形态及微生物菌群的影响

试验旨在研究葡萄糖氧化酶(GOD)和乳酸菌制剂联合应用对肉鸡肠道形态及微生物菌群的影响.选取1日龄AA肉鸡1200只,随机分为4组,Ⅰ组为对照组,正常饮水;Ⅱ组为GOD组,在饮水中添加0.1％ GOD;Ⅲ组为乳酸菌制剂组,在每只鸡饮水中添加1.5×105 CFU/(g·d)乳酸菌制剂;Ⅳ组为GOD与乳酸菌制剂联合应用组...     

平菇菌糠的营养价值研究

试验对不同收菇次数的平菇菌糠进行了营养成分和微生物指标分析测定。结果表明,以棉籽壳和木屑为主要栽培基质的平菇,在第4次和第5次收菇后,平菇菌糠中粗蛋白质含量分别为7.4%、8.1%,氨基酸总量分别为4.26%、5.22%,钙含量分别为1.2%、1.1%。与前三茬平菇菌糠相比,第4茬和第5茬平菇菌糠粗纤维和水含量降低,粗灰分、铁、锌、锰含量升高,并且黄曲霉毒素B1含量极低。结果提示,与前三茬平菇菌糠相比,第4茬和第5茬平菇菌糠的营养价值较理想。     

可降解甲嘧磺隆微生物的筛选及降解作用的初步研究

本研究通过富集培养技术筛选得到了19株可降解甲嘧磺隆的微生物。利用液体培养法就不同微生物菌株对甲嘧磺隆的降解能力进行了测定,结果表明,以JH3、JH2、JH10、SH3菌株的降解效果较好,其中以JH3菌株对甲嘧磺隆的降解能力最强。在此基础上,对JH3菌株的降解作用条件进行了筛选,发现JH3菌株对甲嘧磺隆降解的最适培养基为基础培养基Ⅲ,降解率高达88.66%;研究发现,在基础培养基Ⅲ中,JH3菌株对含有高浓度甲嘧磺隆的单位时间的降解量高于低浓度甲嘧磺隆。     

有机与常规种植蔬菜地土壤微生物群落特征的比较

结合有机农场土壤特性演变的长期定位研究,重点对比分析有机与常规种植蔬菜地土壤微生物群落特征的差异。结果表明:有机蔬菜地土壤微生物量,酸性磷酸酶、脲酶、过氧化氢酶活性及可培养真菌、放线菌菌落数显著高于常规蔬菜地。采用土壤磷脂脂肪酸(PLFA)分析法得到的有机、常规地块土壤细菌生物量分别为12.64 nmol.g-1和7.29 nmol.g-1,并且差异显著(P<0.05)。主成分分析结合R型聚类分析的结果表明,有机种植地块的土壤微生物群落特征的综合评分高于常规种植地块。     

不同林龄人工橘林土壤微生物区系的研究

[目的]了解三峡库区宜昌市郊区不同种植年限的人工橘林土壤微生物区系的变化。[方法]以种植年限不同的3个橘林土壤为研究对象,采用常规方法测定土壤pH、土壤微生物生物量碳、微生物生物量、氮和土壤主要养分含量,采用平板稀释法测定土壤三大类微生物区系的数量。[结果]随着种植年限的增加,不同林龄人工橘林的土壤酸化程度加剧,土壤有机质和全氮含量先增加后降低。土壤微生物总数量呈下降趋势,其中细菌数量显著降低,放线菌数量变化不大,而真菌数量显著增加,土壤中细菌和真菌的比值(B/F)呈现降低趋势。土壤微生物生物量碳在小范围内波动,而土壤微生物生物量氮显著降低。[结论]随着种植年限的增加,土壤pH降低,影响土壤微生物区系、土壤微生物生物量碳、微生物生物量氮和土壤主要养分的变化,进而影响土壤功能的正常发挥。     

微生物脂肪酶概况及其动物营养效应的研究进展

微生物脂肪酶是工业用脂肪酶的重要来源,是生物技术和有机化学应用中广泛使用的酶类之一。文章从微生物脂肪酶来源、酶学特性、在动物消化道中的营养效应和作用机理方面进行综述,主要介绍国内外关于脂肪酶应用在动物饲料方面所取得的一些研究成果,为微生物脂肪酶在饲料中的开发与应用提供参考。     

A case study of biofilter activation and microbial nitrification in a marine recirculation aquaculture system for rearing Atlantic salmon (Salmo salar L.)

Marine recirculation aquaculture system (RAS) is a prominent technology within fish farming. However, the nitrifying bacteria in the biofilter have low growth rates, which can make the biofilter activation a long and delicate process with periods of low nitrification rates and variations in water quality. More knowledge on the microbial development in biofilters is therefore needed in order to understand the rearing conditions that favour optimal activation of the biofilters. In this case study, we investigated the activation of two biofilters in a marine RAS for Atlantic salmon post‐smolt associated with either high or low stocking densities of fish by monitoring the microbial communities and chemical composition. The results showed that the microbial communities in both biofilters were similar during the first rearing cycle, despite variations in the water quality. Nitrifying bacteria were established in both biofilters; however, the biofilter associated with low stocking density had the highest relative abundance of ammonia‐oxidizing Nitrosococcus (1.0%) and nitrite‐oxidizing Nitrospira (2.1%) at the end of the first rearing cycle, while the relative abundance of ammonia‐oxidizing Nitrosomonas (2.3%–2.9%) was similar in both biofilters. Our study showed that low fish stocking density during the first rearing cycle provided low and steady concentrations of ammonium, nitrite and organic load, which can stimulate rapid development of a nitrifying population in new marine RAS biofilters.     

Dietary phytate (inositol hexaphosphate) regulates the activity of intestinal mucosa phytase

The role of dietary phytate (inositol hexaphosphate) in the regulation of intestinal mucosa phytase was investigated in chicks. Seven-day-old chicks were grouped by weight into six blocks of three cages with six birds per cage. Three purified diets [a chemically defined casein diet, a chemically defined casein diet plus sodium phytate (20 g/kg diet) and a chemically defined casein diet plus sodium phytate (20 g/kg diet) and microbial phytase (1000 units/kg diet)] were randomly assigned to cages within each block. Chicks were fed experimental diets from 8 to 22 days of age then killed, and duodenal mucosa and left tibia removed. Phytase activity in duodenal mucosa, growth performance and bone ash content were determined. Addition of phytate to the chemically defined casein diet reduced (p < 0.05) the V(max) of the duodenal brush border phytase, but the K(m) of the enzyme was not affected. Addition of phytate also reduced (p < 0.05) weight gain, feed intake, feed efficiency and percentage ash. Addition of microbial phytase fully restored the feed efficiency (p < 0.05), but V(max) and body weight gain were only partially restored (p < 0.05). In conclusion, it would seem that dietary phytates non-competitively inhibit intestinal mucosa phytase.