Quantitative Risk Assessment of Listeria monocytogenes in French Cold-Smoked Salmon: I. Quantitative Exposure Assessment

A quantitative assessment of the exposure to Listeria monocytogenes from cold-smoked salmon (CSS) consumption in France is developed. The general framework is a second-order (or two-dimensional) Monte Carlo simulation, which characterizes the uncertainty and variability of the exposure estimate. The model takes into account the competitive bacterial growth between L. monocytogenes and the background competitive flora from the end of the production line to the consumer phase. An original algorithm is proposed to integrate this growth in conditions of varying temperature. As part of a more general project led by the French Food Safety Agency (Afssa), specific data were acquired and modeled for this quantitative exposure assessment model, particularly time-temperature profiles, prevalence data, and contamination-level data. The sensitivity analysis points out the main influence of the mean temperature in household refrigerators and the prevalence of contaminated CSS on the exposure level. The outputs of this model can be used as inputs for further risk assessment.     

改革微生物实验教学努力提高其教学质量

通过调整微生物学的实验内容与顺序,采用让学生参与实验准备、开放实验室及开展“第二课堂活动”等形式多样的教学方法,努力提高微生物实验课的教学质量,增强学生的微生物实验技能,培养学生发现问题、综合分析和解决问题的能力.     

微生物学及其检验实验课教学改革初探

微生物学及其检验是医学检验专业的一门重要专业课程,实验教学对于培养学生的实践能力和创新精神起着重要的作用。我们对原有的实验教学内容和教学方法进行了改革,在教学中开展了系列实验,采用了以模拟标本为形式的综合性实验,收到了较好的效果,从而提高了学生运用微生物学知识解决临床医学检验中实际问题的能力。     

食品微生物学实验课教学改革的探讨

本文结合食品微生物学实验教学的实践,针对教学过程中存在的问题,着重探讨了如何在食品微生物学实验教学改革中进行教学内容的调整和教学方法的改进,并提出了在食品微生物学实验教学过程中深化实验教学改革的设想。     

扩招后的"环境微生物学"教学改革实践与探索

近年来,学校招生人数及办学规模的不断扩大,给"环境微生物学"的理论课和实验课的教学带来了新的难题和挑战,如何在新形势下,继续提高教学质量,培养学生综合素质和创新能力是摆在高等教育和教师面前的重要任务.教学改革势在必行,有效的改革实践和探索需要教师不断总结经验,自我提高,同时也需要师生之间的友好互动.     

环境工程微生物学实验教学改革的探索与实践

环境工程微生物学是环境工程专业的主干必修课,环境工程微生物学实验是理论课的主要组成部分。结合多年教学实践,从实验教学计划、教学内容、教学手段和实验考核评价体系等多方面对环境工程微生物学实验教学进行了改革和调整,增设了综合设计性实验,研制了实验多媒体课。新的考核评价体系注重了学生动手能力、创新精神和综合运用知识的能力,切实提高了学生分析问题、解决问题的能力,激发了学生上实验课的热情,增强了学生的参与意识及语言表达能力。     

启发式教学法在"环境工程微生物学"教学中的应用

启发式教学法能有效激发学生学习兴趣和创新意识。本文探讨了多媒体形象启发、理论联系实际、课堂互动竞赛等启发式教学手段在环境工程微生物学教学中的应用,并总结作者提高教学质量的体会。     

Modeling Individual Cell Lag Time Distributions for Listeria monocytogenes

The food industry faces two paradoxical demands: on the one hand, foods need to be microbiologically safe for consumption and on the other hand, consumers want fresh, minimally processed foods. To meet these demands, more insight into the mechanisms of microbial growth is needed, which includes, among others, the microbial lag phase. This is the time needed by bacterial cells to adapt to a new environment (for example, after food product contamination) before starting an exponential growth regime. Since food products are often contaminated with low amounts of pathogenic microorganisms, it is important to know the distribution of these individual cell lag times to make accurate predictions concerning food safety. More precisely, cells with the shortest lag times (i.e., appearing in the left tail of the distribution) are largely decisive for the outgrowth of the population. In this study, an integrated modeling approach is proposed and applied to an existing data set of individual cell lag time measurements of Listeria monocytogenes. In a first step, a logistic modeling approach is applied to predict the fraction of zero-lag cells (which start growing immediately) as a function of temperature, pH, and water activity. For the nonzero-lag cells, the mean and variance of the lag time distribution are modeled with a hyperbolic-type model structure. This mean and variance allow identification of the parameters of a two-parameter Weibull distribution, representing the nonzero-lag cell lag time distribution. The integration of the developed models allows prediction of a global distribution of individual cell lag times for any combination of environmental conditions in the interpolation domain of the original temperature, pH, and water activity settings. The global fitting quality of the model is quantified using several measures indicating that the model gives accurate predictions, erring slightly on the fail-safe side when predicting the shortest lag times.     

案例教学法在医学微生物学教学中的运用

在医学微生物学教学中采用案例教学法,重点在于设计合理的案例,提出合适的问题以及对问题进行的讨论。该教学方法激发了学生的学习兴趣,也调动了教师的创造性思维,有利于培养学生分析问题和解决问题的能力。     

《微生物学》课程立体化教学模式的探索与实践

微生物学是高校许多专业必修的一门基础课程,要提高该课程的教学质量,应立足课程基本要求,紧密跟踪国际最新进展,选用和参考国内外优秀教材及教学课件,充分利用现代信息技术和教学手段,制作互动式教学课件,以实现微观世界宏观化、文字叙述图片化、平面内容立体化、图片影像真实化、静态模式动态化、复杂过程简单化、教学方法多样化的立体教学模式.