不同菌剂处理对玉米芯发酵过程中纤维素降解及相关酶活性的影响

以玉米芯为发酵原料,EM酵素菌、有机物料腐熟剂、金宝贝菌剂3种市售菌剂为发酵菌剂,研究了3种菌剂处理对玉米芯发酵过程中纤维素降解及相关酶活性的影响。结果表明,不同发酵菌剂处理后,纤维素降解酶的活性均增强,玉米芯基质中的纤维素、半纤维素降解率高于对照,其中EM酵素菌处理效果最佳;3种菌剂处理使木质素过氧化物酶活性增强,可有效提高玉米芯基质中的木质素降解率,其中金宝贝菌剂处理效果最佳,与对照相比降解率提高21.1%~50.5%。     

Effect of organic nitrogen fertilizers on microbial populations associated with bermudagrass putting greens

 Four natural organic fertilizers, alone or in combination with the synthetic organic fertilizer isobutylidene diurea (IBDU), were compared with IBDU alone for their effect on soil/root microbial populations associated with bermudagrass grown on a golf course putting green in southern Florida, USA. Populations of total fungi, total bacteria, fluorescent pseudomonads, Stenotrophomonas maltophilia, actinomycetes and heat-tolerant bacteria were monitored every 3 months during the 2-year study. On only one sampling date and for only one bacterial population (S. maltophilia) was a significant difference in microbial populations obtained among the fertilizer treatments. However, the S. maltophilia populations associated with the natural organic fertilizer treatments were not significantly different from the synthetic organic IBDU fertilizer treatment. Received: 4 April 1997     

不同处理牛羊粪便堆积发酵试验效果比较

利用发酵菌剂对不同处理的试验Ⅰ组、试验Ⅱ组、试验Ⅲ组、试验Ⅳ组、试验Ⅴ组和对照组进行堆积发酵试验,在发酵过程中比较了不同试验组的温度、水分、挥发性总固体、pH、细菌群落的变化,以及对牧草籽发芽率、虫卵杀除率和总养分的影响。     

对虾白黑斑病的病原病因研究

对虾白黑斑病是养殖中国对虾的常见病，曾被怀疑是细菌性疾病，本试验通过对病虾肝胰腺、血液和病灶组织的细菌分离，对正常虾用白黑斑虾的细菌注射感染等一系列试验发现：细菌或其它生物性病原与对虾白黑斑病并无直接关系。     

橡胶草种植前后土壤微生物细菌多样性研究(Ⅱ)——高级分析

[目的]研究橡胶草种植前后土壤微生物细菌的多样性。[方法]对大田种植橡胶草前后的土壤理化性质进行考察,并通过454测序技术对土壤微生物细菌多样的数据序列进行高级分析。[结果]橡胶草种植后土壤的全氮和全磷略高于种植前,有机质稍有下降。土壤细菌的OTU数在橡胶草种植前后相差不大。群落结构分析表明,橡胶草种植前后的细菌组成大致相同,但各物种所占比例有差异,大多数的细菌是不可培养的,其中与氮有关的菌属柱状区所占比例最大。PCA主成分分析表明橡胶草种植前后土壤微生物群落在细菌水平上相近,这个结果与群落分布柱状图相吻合。RDA分析表明,土壤pH值、有机质、土壤含水率、土壤全氮和全磷与细菌呈正相关,土壤容重与细菌呈负相关。[结论]试验测序数据表明,橡胶草种植前后的土壤微生物细菌在OUT水平上多样性丰富,在属的水平上群落结构组成相近,种植橡胶草后土壤理化性质发生了改变。     

Microbial community indigenous to the earthworm Eisenia foetida

 Microbial populations of the earthworm Eisenia foetida, their casts and farmyard manure (FYM) in which E. foetida had lived were enumerated with the dilution plate method using several media. The microbial community of earthworms appeared to be similar to that of the FYM in which they had lived, while that of earthworms starved in distilled water for 24 h greatly differed from that of the FYM. The community of the starved earthworms consisted exclusively (more than 90%) of fast growers, which were defined as those that formed their colonies within 2 days, unlike that of the FYM (10–30%). About 30 isolates were randomly chosen and some physiological properties were examined. The community of starved earthworms consisted exclusively of Gram-negative, oxidase-positive, fermentative bacteria, whereas bacteria from the FYM were much more diverse and there were no fermentative bacteria in the FYM. The predominant bacteria species of the starved earthworms were identified as Aeromonas hydrophila and considered to be indigenous to the earthworm E. foetida. Received: 18 June 1999     

Earthworms increase the ratio of bacteria to fungi in northern hardwood forest soils, primarily by eliminating the organic horizon

The exotic earthworm invasion in hardwood forests of the northern United States is associated with many ecosystem-level changes. However, less is known about the effects of the invasion on the composition of the soil microbial community through which ecosystem-level changes are mediated. Further, earthworm effects on soil microbial community composition have not been well studied in the field. To evaluate changes in bacterial and fungal abundance associated with the earthworm invasion we quantified bacterial and fungal biomass by microscopic counts in paired earthworm-invaded (earthworm) and earthworm-free (reference) plots in five forest stands in central New York (USA). Earthworms significantly increased the ratio of bacteria to fungi on an area basis (per m²), by more than two times in mid-summer and early autumn. While this effect was associated primarily with the lack of the fungal-dominated organic horizon in earthworm plots, a higher ratio of bacteria to fungi in the surface 5 cm mineral soil also contributed as it developed between spring and mid-summer. Earthworm reduction of fungal biomass was confirmed by substantially lower growth of fungal hyphae into mesh sand bags in earthworm compared to reference plots. Burrowing activity by the earthworm Lumbricus terrestris increased the ratio of bacteria to fungi over the short-term within earthworm plots, introducing small-scale spatial heterogeneity associated with burrows. Our study suggests that the exotic earthworm invasion in these northern hardwood forests markedly increased the ratio of bacteria to fungi by eliminating the fungal-rich organic horizon, and was associated localized increases in bacterial vs. fungal abundance in mineral soil, setting the stage for future research into linkages between the earthworm invasion, bacterial and fungal abundance, and ecosystem processes.     

日粮中添加不同纤维分解菌对鹅生产性能的影响

为研究日粮中添加不同纤维分解菌对鹅生产性能的影响,试验选用0日龄健康农安本地鹅64只,随机分成4组,每组16只。试验组从0日龄每3 d饲喂一次纤维分解菌,喂菌量为10⁹ CFU/mL,纤维分解菌分别为:从鹅肠道内分离扩增的芽孢纤维分解菌(A组);从白蚁肠道内分离扩增的芽孢纤维分解菌(B组);从牛粪中分离扩增的芽孢纤维分解菌(C组);对照组用等量的蒸馏水代替。测定鹅日增重、采食量、料重比。结果表明,A、B、C组提高了鹅的日增重、采食量,显著降低了料重比,B组作用效果较好、A组次之,C组较差。     

一株可降解苹果废弃枝条的生防细菌鉴定

筛选对废弃苹果枝条具有降解作用的细菌,为农业废弃物的资源化利用奠定基础。首先利用稀释涂布法从采集的带菌苹果枝段中分离,再通过羧甲基刚果红培养基和复筛培养基挑选出产纤维素酶的菌株,利用发酵培养基验证筛选菌株的纤维素降解能力,进行腐烂病（Valsa mali）的对峙试验并测定其生防潜力,最后通过菌落形态、显微观察和gyrA序列的16S rDNA分析对细菌进行鉴定。从采集的苹果枝条中共分离出3株细菌,其中X-2菌株对苹果枝条具有降解作用,其最适生长pH为8,最适生长温度为30 ℃左右。菌株分泌产生的滤纸酶（FPAase）、β-葡萄糖苷酶和羧甲基纤维素酶（CMCase）活力分别高达（12.78±0.03） U/mL、（8.63±0.64） U/mL和（8.36±0.02） U/mL,枝条纤维素降解率高达12.36%±0.44%,经过16S rDNA序列测定和Blast 同源序列检索,得出该生防菌株X-2为解淀粉芽孢杆菌 (Bacillus amyloliquefaciens)。菌株X-2可以满足废弃苹果枝条的降解需求,其在碱性条件下生长良好,有望应用于碱性地区废弃枝条纤维素的降解。     

A single application of Cu to field soil has long-term effects on bacterial community structure, diversity, and soil processes

Long-term diversity-disturbance responses of soil bacterial communities to copper were determined from field-soils (Spalding; South Australia) exposed to Cu in doses ranging from 0 through to 4012 mg Cu kg⁻¹ soil. Nearly 6 years after application of Cu, the structure of the total bacterial community showed change over the Cu gradient (PCR-DGGE profiling). 16S rRNA clone libraries, generated from unexposed and exposed (1003 mg Cu added kg⁻¹ soil) treatments, had significantly different taxa composition. In particular, Acidobacteria were abundant in unexposed soil but were nearly absent from the Cu-exposed sample (P<0.05), which was dominated by Firmicute bacteria (P<0.05). Analysis of community profiles of Acidobacteria, Bacillus, Pseudomonas and Sphingomonas showed significant changes in structural composition with increasing soil Cu. The diversity (Simpsons index) of the Acidobacteria community was more sensitive to increasing concentrations of CaCl-extractable soil Cu (Cu_Ext) than other groups, with decline in diversity occurring at 0.13 Cu_Ext mg kg⁻¹ soil. In contrast, diversity in the Bacillus community increased until 10.4 Cu_Ext mg kg⁻¹ soil, showing that this group was 2 orders of magnitude more resistant to Cu than Acidobacteria. Sphingomonas was the most resistant to Cu; however, this group along with Pseudomonas represented only a small percentage of total soil bacteria. Changes in bacterial community structure, but not diversity, were concomitant with a decrease in catabolic function (BioLog). Reduction in function followed a dose-response pattern with Cu_Ext levels (R²=0.86). The EC₅₀ for functional loss was 0.21 Cu_Ext mg kg⁻¹ soil, which coincided with loss of Acidobacteria diversity. The microbial responses were confirmed as being due to Cu and not shifts in soil pH (from use of CuSO₄) as parallel Zn-based field plots (ZnSO₄) were dissimilar. Changes in the diversity of most bacterial groups with soil Cu followed a unimodal response - i.e. diversity initially increased with Cu addition until a critical value was reached, whereupon it sharply decreased. These responses are indicative of the intermediate-disturbance-hypothesis, a macroecological theory that has not been widely tested in environmental microbial ecosystems.