Bacterial dynamics during the spontaneous fermentation of cassava dough in gari production

The microbial dynamics and diversity during solid substrate fermentation of cassava, a case study of gari production in West Africa, was investigated. The 16S rDNA gene sequence analysis of the PCR-Denaturing Gradient Gel Electrophoresis (PCR–DGGE) analysis of microbial community DNA and Pulsed Field Gel Electrophoresis (PFGE) of selected isolates as well as culturing techniques using different selective media were used to monitor the bacterial dynamics during cassava fermentation. The V3 variable region of the 16S gene was analyzed and the closest relatives of Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus pentosus, Lactobacillus acidophilus and Lactobacillus casei were identified by sequencing of the DGGE band amplimers. The DGGE amplimers also revealed the succession and dynamics of LAB; there was a progressive increase in their population proportional to the fermentation period. The analysis of the PFGE band patterns showed that five diverse species of LAB were involved in the fermentation. The representative isolate of each of the PFGE clusters was phenotypicaly identified as L. plantarum, L. fermentum and Leuconostoc mesenteroides by the API 50 CHL sugar fermentation profile. These combinations of parameters identified heterofermentative LAB as bacteria that initiated the fermentation, reduced the pH below four and increased the acidity of the fermentation mash. Information such as this is relevant for the development of starter cultures and predictability of the process for traditional fermented foods and to aid their intermediate and large scale production.     

瓶装饮用纯净水细菌数量变化规律研究

对瓶装饮用纯净水细菌数量变化规律进行了研究。在某生产厂家采集5加仑和600ml塑料瓶（桶）装纯净水保存于室温。自生产后3h,每24～56h检验菌落总数,至保存35d止。保存过程中,所有600ml瓶装水试样的细菌数量均急剧增加,在5～7d内达到高峰,菌数范围在＜1～1．53×105ml-1之间,之后,生长曲线呈现双峰。同样情况也出现在5加仑桶装成品中。     

三碘化亚甲基蓝法测定硫酸盐还原菌菌量

三碘化亚甲基蓝(TIMB)在培养液中与维生素C反应生成亚甲基蓝氧化型,溶液呈蓝色,再遇S~(2-)则生成亚甲基蓝还原型,溶液变为无色。本文利用这一特征性变色反应,在经典绝迹稀释法(FeS法)的基础上建立了检测SRB菌量的新方法——TIMB法。此法较FeS法快速,且测定时无H_2S释出。     

江汉油田注水采油设备的腐蚀与防护

随着采出原油含水率增大,江汉油田地面和地下注水、输油管线都发生严重腐蚀。通过油田注水水质监测,大量地面、井下挂片腐蚀试验,腐蚀状况和腐蚀物分析,室内模拟试验,查明引起腐蚀的因素是 SRB、高 Cl~-含量以及溶解 O_2、CO_2和 H_2S,其中以 SRB 最为重要。讨论了各种因素引起腐蚀的机理。提出了相应的防腐蚀措施。     

油田注水系统中的细菌类型及抑制方法

详细介绍了油田注水系统中主要存在的细菌类型、生存条件、危害机理等，并总结概括了杀菌剂的种类、选用原则和投加方法，在最后，对油田注水用杀菌剂的发展方向进行了展望。     

交联黄原胶调剖引起采出水中细菌增生的研究

华北岔河集油田使用交联黄原胶调整注水井吸水剖面,发现调剖后油井采出水中SRB与TGB细菌含量增加,室内实验研究表明,在粘稠液状商品黄原胶的清水的油田污水溶液中,当黄原胶度大于500mg/L时,确有细菌增生现象发生,加入适量杀菌剂如≤mg/L甲醛液邓可抑制细菌生长,繁殖,矿场18口注水井调剖试验结果表明,使用用油田污水配制的黄原胶（2000mg/L)蜡酸铬（1000mg/L) 冻胶体系,当甲醛液另量为500mg/L时,调剖后油井采出水中细菌含量有所增加,甲醛液加量为1000mg/L时,调剖后采出水中细菌含量不变,甲醛液加量为1500mg/L时,调剖后采出水中的细菌含量有所减少。     

老河口油田注水管网管损分析及治理

桩西采油厂老河口油田于1998年12月投入注水开发。目前注水系统建有注水支干线24条长32．6km,单井注水管线78条长29．7km。由于注水时间长和注水水质不合格,注水管线存在腐蚀堵塞情况,导致单井注水压力损失（最高4．9MPa）、水井欠注等问题。针对这一现象,采用XRD分析、细菌分析、水分析、酸溶分析等方法,对注水管网的腐蚀物主要成分、生成机理进行室内实验分析,通过酸化解除管线内的堵塞物,降低单井注水压力损失（最低0．1MPa）,取得良好的效果,并提出预防堵塞物产生的建议。     

Use of MS2 Coliphage as a Surrogate for Enteric Viruses in Surface Waters Disinfected with Ozone

The purpose of this study was to determine the relative inactivation of MS2 coliphage (American Type Culture Collection strain 15597-B1) and heterotrophic plate count bacteria using raw surface water under a variety of naturally occurring conditions. It was found that the applied ozone dose and dissolved organic carbon had the most impact on ozone disinfection of MS2 coliphage and HPC bacteria. The dissolved organic carbon was found to compete for the ozone and significantly reduce the inactivation of both the coliphage and the bacteria. Furthermore, it was observed that the presence of any ozone residual inactivated greater than 4 logs MS2 coliphage and 2 logs heterotrophic plate count bacteria within a 30 second contact time. Ozone residuals greater than 0.20 mg/L inactivated greater than 5 logs MS2 coliphage and 3 logs heterotrophic plate count bacteria also within 30 second contact time. Comparison of inactivation studies indicate that MS2 coliphage is probably more sensitive to ozone than enteric viruses. It was concluded that the regulatory agencies should reevaluate their recommendations for using MS2 coliphage as an ozone disinfection indicator of enteric viruses.     

Bacteria in a water‐damaged building: associations of actinomycetes and non‐tuberculous mycobacteria with respiratory health in occupants

We examined microbial correlates of health outcomes in building occupants with a sarcoidosis cluster and excess asthma. We offered employees a questionnaire and pulmonary function testing and collected floor dust and liquid/sludge from drain tubing traps of heat pumps that were analyzed for various microbial agents. Forty‐nine percent of participants reported any symptom reflecting possible granulomatous disease (shortness of breath on exertion, flu‐like achiness, or fever and chills) weekly in the last 4 weeks. In multivariate regressions, thermophilic actinomycetes (median = 529 CFU/m²) in dust were associated with FEV₁/FVC [coefficient = ?2.8 per interquartile range change, P = 0.02], percent predicted FEF_25–75% (coefficient = ?12.9, P = 0.01), and any granulomatous disease‐like symptom [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.45?6.73]. Mycobacteria (median = 658 CFU/m²) were positively associated with asthma symptoms (OR = 1.5, 95% CI = 0.97?2.43). Composite score (median = 11.5) of total bacteria from heat pumps was negatively associated with asthma (0.8, 0.71?1.00) and positively associated with FEV₁/FVC (coefficient = 0.44, P = 0.095). Endotoxin (median score = 12.0) was negatively associated with two or more granulomatous disease‐like symptoms (OR = 0.8, 95% CI = 0.67?0.98) and asthma (0.8, 0.67?0.96). Fungi or (1→3)‐β‐D‐glucan in dust or heat pump traps was not associated with any health outcomes. Thermophilic actinomycetes and non‐tuberculous mycobacteria may have played a role in the occupants' respiratory outcomes in this water‐damaged building.     

烘烤方式及烘烤条件对烤烟烘烤中细菌变化的影响

烤烟烘烤过程中微生物的活动对烟叶质量有重要影响.为了解烘烤条件对细菌活动的影响,试验观察了不同烘烤方式和烘烤条件下细菌的变化状况.结果表明,细菌种类随烘烤时间的增加而减少,烘烤方式和烘烤条件对细菌种类的变化无明显影响.细菌数量则是在变黄期逐渐增加,烟叶变黄时达最大,以后逐渐减少.在密集烘烤中和高温高湿条件下,细菌量高于普通烘烤和低温低湿烘烤,说明采用低温低湿变黄有可能抑制细菌活动.