微生物几丁质酶的分子生物学研究

几丁质酶对几丁质的生物降解具有重要作用.微生物产生的几丁质酶种类较多,彼此之间差异较大,但它们也具有一些相似的结构,如信号肽、催化区域,几丁质结合区域等.本文总结了微生物几丁质酶这些方面的特点,并对它的表达调控和应用前景进行探讨.     

高职园艺专业农业微生物学教学改革的探索

从理论教学和实验教学两方面探索了高职园艺试点专业的农业微生物学的教学改革。选定原核微生物、真核微生物、非细胞生物、微生物的营养和生长、农业生产中的微生物应用作为理论课的主讲内容。在实验教学方面 ,通过设计一个大实验 ,让学生系统掌握无菌操作技术、纯培养技术、显微技术和灭菌技术     

畦灌配施保水剂改善杨树林下土壤物理性状提高微生物活性

为指导杨树人工林节水灌溉和增产,通过大田试验,比较研究常规畦灌(720 m3/hm2)、常规畦灌量60%、常规畦灌量30%、60%常规畦灌量配施保水剂和30%常规畦灌量配施保水剂等处理对杨树林下土壤容重、微生物量碳和氮、微生物活性及生长的影响。结果表明:同常规畦灌相比,60%常规畦灌量配施保水剂处理明显降低了土壤容重,且显著增加了土壤总孔隙度和毛管孔隙度,其土壤容重分别较常规畦灌、常规畦灌量60%、常规畦灌量30%和30%常规畦灌量配施保水剂处理下降6.62%、11.19%、16.45%和7.97%;显著提高了土壤微生物量碳、氮含量,并明显增强了土壤微生物呼吸作用,其微生物呼吸速率较常规畦灌、常规畦灌量60%、常规畦灌量30%和30%常规畦灌量配施保水剂处理分别高出13.89%、24.24%、41.38%和12.33%;同时,60%常规畦灌量配施保水剂处理还降低了代谢熵,与其他4种处理相比其下降幅度分别为5.96%、8.84%、11.72%和4.78%。此外,该处理的材积生长率达到最大值,并显著大于其他处理(P0.05)。与60%常规畦灌量配施保水剂相比,30%常规畦灌量配施保水剂处理对林下土壤及材积的作用效果较小。相关分析表明,材积生长率与毛管孔隙度、代谢熵有极显著相关关系(P0.01),与土壤容重、微生物量碳和氮、微生物呼吸有显著相关关系(P0.05)。综合分析认为,适宜的节水灌溉措施(常规畦灌量60%与保水剂组合)有利于改善杨树林下土壤的物理环境,增强微生物活性,并促进杨树林木的生长。     

Housefly Larvae (Musca domestica) Vermicompost on Soil Biochemical Features for a Chrysanthemum (Chrysanthemum morifolium) Farm

ABSTRACT

The housefly larvae (Musca domestica) vermireactor is capable of highly efficient waste reduction for swine manure management; however, effectiveness of larvae-vermicompost land utilization and the associated impact on soil environment are poorly understood. This study, which integrated incubation pot experiments and field plot tests on a chrysanthemum (Chrysanthemum morifolium) farm, was designed to investigate soil biochemical and microbial functions in response to inorganic fertilizer (NPK), vermicompost (VC) application, and/or combination of inorganic fertilizer and vermicompost (I + V). Pot experiments indicated that available soil nitrogen (N), phosphorus (P), and potassium (K) were significantly higher (21%-43%, 206%-306%, and 35%-36%, respectively) with VC treatment compared to NPK treatment; meanwhile, soil organic carbon (C), N and P mineralization was increased by 46%-57%, 53%-70%, and 30%-113%, respectively. Vermicompost application increased soil highly labile organic C by 19% to 42%. Vermicompost also enhanced soil enzymatic activities: 37%-68% for dehydrogenase, 22%-107% for urease, and 3.4%-56% for phosphatases, but activities of soil β-1,4-glucosidase and β-1,4-N-acetylglucosaminidase were reduced by 17%-53% and 24%-42%, respectively. Compared to pot experiment, continuous land application of vermicompost overwhelmingly caused soil nutrient accumulation, increased soil C stock and microbial biomass, enhanced soil mineralization, and improved C-, N-, and P-related enzymatic activities. Co-inertia analysis indicated that soil fertility indices positively correlated with most microbiological indices. This work reveals VC as a new biofertilizer for crop production and highlights its merit on soil health improvement.     

Replacement of soybean oil by Hermetia illucens fat in turkey nutrition: effect on performance,digestibility, microbial community,immune and physiological status and final product quality

ABSTRACT

1. The aim of the present study was to investigate the effect of partial (50%) or total replacement of soybean oil (SO) by black soldier fly larvae (BSFL) fat on the growth performance, coefficients of apparent nutrient digestibility, selected internal organ weights and length, pancreatic enzyme activity and gastrointestinal tract (GIT) microecology modulation, as well as microbiota activity, physiological and immunological responses in young turkey poults.

2. A total of 216, seven day old female turkeys (B.U.T 6) were randomly distributed to three dietary treatments using six replicate pens per group with 12 birds per pen. The following design of the trial was applied: SO 100% soybean oil; BSFL50 a 50/50 combination of SO and BSFL fat; or 100% BSFL fat (total replacement of SO).

3. The use of BSFL fat did not affect the growth performance, nutrient digestibility, GIT morphology, or quality of the breast and thigh muscles. However, reduced trypsin activity was noticed in the BSFL100 group, but this had no effect on digestibility. Total replacement of SO reduced proliferation of potentially pathogenic bacteria, i.e., Enterobacteriaceae spp., as well as decreasing levels of IL-6, while partial substitution lowered the TNF-α concentration.

4. The replacement of commonly used SO by BSFL fat can be successfully applied in young turkey poult nutrition. BSFL fat may be considered an antimicrobial agent and support immune responses.     

External contamination of broilers by Campylobacter spp. increases from the farm to the slaughterhouse

ABSTRACT

1. In this study, classical and molecular microbiological methods for detection and quantification of Campylobacter spp. were used to estimate their prevalence in faecal samples and skin swabs collected from 31 broiler flocks (20 farms) in Portugal, and measure the impact of transport-related factors on the expected rising excretion rates from the farm to the slaughterhouse.

2. Data on husbandry practices and transport conditions were gathered, including time in transit, distance travelled or ante-mortem plant-holding time.

3. A generalised linear mixed model was used to evaluate the significance of a potential post-transport rise in Campylobacter spp. counts and to assess risk determinants.

4. At least one flock tested positive for Campylobacter spp. in 80% of the sampled farms. At the slaughterhouse, Campylobacter spp. were detected in all faecal samples, C. jejuni being the most commonly isolated.

5. A post-transport rise of Campylobacter spp. counts from skin swabs was observed using classical microbiological methods (from a mean of 1.43 to 2.40 log₁₀ CFU/cm²) and molecular techniques (from a mean of 2.64 to 3.31 log₁₀ genome copies/cm²).

6. None of the husbandry practices or transport-related factors were found to be associated with Campylobacter spp. counts.

7. This study highlights the need for more research to better understand the multi-factorial nature of Campylobacter spp., a public health threat that was found to be highly prevalent in a sample of Portuguese poultry farms.     

高职类食品微生物检验技术课程教学改革探讨

食品微生物检验技术是一门实践性和应用性很强的学科,是质检专业的职业技术核心课程之一。通过对教学内容、教学方法以及课程考试考核等方面的改革,提高食品微生物检验技术课程教学质量及学生的职业能力。使学生实践动手能力大大加强,为学生的就业奠定坚实基础。     

Cu污染条件下封闭循环水养虾系统的效能

为获得Cu2+污染对封闭循环水养虾系统的影响,选用0.3 mg/L Cu2+浓度,研究其对系统中水质、对虾生长、存活及生物滤器水处理效能的影响。结果表明,经过84 d的试验,养殖水体中Cu2+质量浓度在系统水处理单元作用下降为(0.089±0.012)mg/L,对虾能正常生长和存活,0.3 mg/L Cu2+处理质量浓度对生物滤器的化学需要量（COD）、NH4-N和NO2-N去除率及滤器中异养细菌、氨氧化菌和亚硝酸盐氧化菌的数量不造成显著影响。处理系统对虾体内Cu质量分数为(42.91±6.10)mg/kg,与对照中质量分数(29.36±4.06)mg/kg相比,具有显著差异,但均在国家无公害食品水产品中有毒有害物质限量标准（Cu≤50 mg/kg）范围内。在0.3 mg/L Cu2+质量浓度污染下,封闭循环水养虾系统仍能提供较好的水质条件,获得较高的产量和较低的饵料转化率,所养对虾符合无公害水产品要求。     

Dose-effect Study of Lipoic Acid Supplementation on Growth Performance in a Weaned Rat Model

The present study investigated the doseeffect relationship of graded levels of lipoic acid supplementation on growth performance and small intestinal development in a weaned rat model.Seventy-two weaned Sprague-Dawley rats,were fed semipurified diets(n=12),either unsupplemented(group Ⅰ)or supplemented with 12.5,25,125,or 250 mg/kg body weight(BW)fipoic acid(groups Ⅲ,Ⅳ,Ⅴ,and Ⅵ),with 200 mg/kg BW aureomycin as the antibiotic control(group Ⅱ).The experiment lasted 21 days.Growth performance was not significantly different (P＞0.05)between rats under the antibiotc control (group Ⅰ)and rats fed low levels(12.5 and 25 mg/kg BW)of lipoic acid(groups Ⅳ and Ⅳ).In contrast,high level(125 and 250 mg/kg BW)lipoic acid supplementation(groups Ⅴ and Ⅵ)(P＜0.05)reduced weight gain,feed consumption,and feed efficiency.In addition,high levels(125 and 250 mg/kg BW)of lipoic acid significantly(P＜0.05)reduced the villus height/crypt depth ratio,as well as the numbers of lactobacillus.total aerobes.and total anerobes in the gastrointestinal tract compared with the other treatments,which meant that high levels of lipoic acid impaired intestinal morphology and disordered the balance of intestinal microbiology.Furthermore,the results showed that high leveIs of lipoic acid supplementation(P＜0.05)elevated interferonγ and intefleukin-2,but dramatically(P＜0.05)depressed interleukin-4 and interleukin-10 compared with the low levels of lipoic acid supplementation and the control group,which indicated that high levels of lipoic acid would induce bias of Th1/Th2 lymphocytes.Taken together,the results indicate that lipoic acid supplementation can't improve growth performance and intestinal development of normal animals,especially,high levels(≥125 mg/kg BW)of lipoic acid supplementation restrained growth performance and intestinal development,in association with unbalance of certain cytokines.