Development of an industrial medium for economical 2,3-butanediol production through co-fermentation of glucose and xylose by Klebsiella oxytoca

An industrial medium containing urea as a sole nitrogen source, low levels of corn steep liquor and mineral salts as nutrition factors to retain high 2,3-butanediol production through co-fermentation of glucose and xylose (2:1, wt/wt) by Klebsiella oxytoca was developed. Urea and corn steep liquor were identified as the most significant factors by the two-level Plackett–Burman design. Steepest ascent experiments were applied to approach the optimal region of the two factors and a central composite design was employed to determine their optimal levels. Under the optimal medium, the yield of 2,3-butanediol plus acetoin relative to glucose and xylose was up to 0.428 g/g, which was 85.6% of theoretical value. The cheap nitrogen source and nutrition factors combining the co-fermentation process using lignocellulose derived glucose and xylose as the carbon source in the developed medium would be a potential solution to improve the economics of microbial 2,3-butanediol production.     

肺炎链球菌SP0306蛋白的表达纯化及结晶研究

SP0306蛋白是肺炎链球菌TIGR4菌株中的一种假想的转录因子,但其蛋白三维结构及生物学功能尚未明了,生物信息学分析提示其可能调控碳水化合物代谢相关基因的表达。成功构建了SP0306蛋白的全长表达载体PET28a-sp0306,利用大肠杆菌BL21(DE3)菌株进行原核表达,获得了以可溶形式表达的目的蛋白。经Ni-NTA柱亲和层析及DEAE阴性离子交换层析纯化后,获得了高纯度的目的蛋白。采用悬滴气相扩散法获得了质量较好的SP0306蛋白晶体,并初步进行了晶体X射线衍射,为其最终的三维结构解析及生物学功能研究奠定了基础。     

多重聚合酶链反应与荚膜肿胀试验对肺炎链球菌血清分型的比较研究

为评估多重聚合酶链反应（PCR ）对肺炎链球菌血清分型的可行性,分别采用多重PCR和荚膜肿胀试验对568株肺炎链球菌进行血清分型,并对分型结果进行比较分析。结果显示,568株肺炎链球菌中,213株通过荚膜肿胀试验分出16个血清群,主要有血清群19（23．1％,131／568）、6（5．3％,30／568）、23（1．6％,9／568）、14（1．4％,8／568）、9（1．1％,6／568）、15（1．1％,6／568）等,分型率为37．5％（213／568）;356株通过多重PCR分出21个血清群,主要有血清群19（27．8％,158／568）、23（8．5％,48／568）、6（7．4％,42／568）、14（4．4％,25／568）、3（4．2％,24／568）、15（3．5％,20／568）等,分型率为62．7％（356／568）。荚膜肿胀试验鉴定出血清群4和18,但多重PCR未能鉴定;多重PCR鉴定出血清群5、12、35、16、17和22,但荚膜肿胀试验未能鉴定。多重PCR与荚膜肿胀试验对19F、19A血清型的鉴定无显著差异。结果提示,这2种方法对肺炎链球菌血清分型结果有差别,多重PCR的分型率高于荚膜肿胀试验。对来源复杂的标本进行肺炎链球菌血清分型,2种方法可相互补充,以提高分型率。     

Characterisation of 20-kDa lectin-spermagglutinin from Arum maculatum that prevents Chlamydia pneumoniae infection of L-929 fibroblast cells

A novel lectin from the root of Arum maculatum was isolated by saline extraction and purified by cold ethanol precipitation and subsequent fractionation on Superose 6 column. The lectin named A. maculatum agglutinin is a non-glycosylated protein with 20-kDa molecular mass agglutinating human ejaculated spermatozoa, but not human erythrocytes. The agglutination was blocked in the presence of N-acetylneuraminic acid indicating that the lectin is sialoglycoprotein specific. Chlamydia pneumoniae strain AR-39 showed considerable potential to grow in murine L-929 fibroblast cells. Pretreatment of the cell monolayers with purified lectin reduced the entry and intracellular replication of C. pneumoniae. These results suggest that the isolated lectin prevents attachment by binding to a C. pneumoniae specific sialoglycoprotein receptor expressed on the surface of L-929 fibroblast cells.     

The circulatory small non-coding RNA landscape in community-acquired pneumonia on intensive care unit admission

Community-acquired pneumonia (CAP) is a major cause of sepsis. Despite several clinical trials targeting components of the inflammatory response, no specific treatment other than antimicrobial therapy has been approved. This argued for a deeper understanding of sepsis immunopathology, in particular factors that can modulate the host response. Small non-coding RNA, for example, micro (mi)RNA, have been established as important modifiers of cellular phenotypes. Notably, miRNAs are not exclusive to the intracellular milieu but have also been detected extracellular in the circulation with functional consequences. Here, we sought to determine shifts in circulatory small RNA levels of critically ill patients with CAP-associated sepsis and to determine the influence of clinical severity and causal pathogens on small RNA levels. Blood plasma was collected from 13 critically ill patients with sepsis caused by CAP on intensive care unit admission and from 5 non-infectious control participants. Plasma small RNA-sequencing identified significantly altered levels of primarily mature miRNAs in CAP relative to controls. Pathways analysis of high or low abundance miRNA identified various over-represented cellular biological pathways. Analysis of small RNA levels against common clinical severity and inflammatory parameters indices showed direct and indirect correlations. Additionally, variance of plasma small RNA levels in CAP patients may be explained, at least in part, by differences in causal pathogens. Small nuclear RNA levels were specifically altered in CAP due to Influenza infection in contrast to Streptococcus pneumoniae infection. Pathway analysis of plasma miRNA signatures unique to Influenza or Streptococcus pneumoniae infections showed enrichment for specific proteoglycan, cell cycle, and immunometabolic pathways.     

肺炎支原体肺炎患儿外周血白介素的表达与肺功能变化的相关性

目的:探讨肺炎支原体(MPP)肺炎患儿外周血中IL-10、IL-17的表达水平与肺功能变化的相关性。方法:选取70例肺炎支原体肺炎患儿为研究对象,以是否有哮鸣音分为喘息组和非喘息组,以30例健康儿童为对照组,空腹采血5ml,分离血清,ELISA检测血清中IL-10、IL-17的表达水平,肺功能检测仪检测受检者的第一秒用力呼气容积(PEV1),最大呼气流量(PEF),用力肺活量(FEV1/FVC)。结果:喘息组中IL-10的表达水平与对照组相比差异显著(P0.05),喘息组中IL-10的表达水平与非喘息组相比差异显著(P0.05),喘息组中IL-17的表达水平与对照组相比差异显著(P0.05),喘息组中IL-17的表达水平与非喘息组相比差异显著(P0.05)。喘息组和非喘息组中IL-10水平均低于对照组,喘息组和非喘息组中IL-17水平均高于于对照组。非喘息组较喘息组PEV1、PEF、PVE1/FVC值高,差异显著(P0.05)。肺炎支原体肺炎患儿血清中的IL-10的水平与PEV1、PEF、PVE1/FVC呈正相关,肺炎支原体肺炎患儿血清中的IL-17的水平与PEV1、PEF、PVE1/FVC呈负相关。结论:肺炎支原体肺炎患儿血清中IL-10、IL-17的表达水平与肺功能密切相关。     

Invasive pneumococcal disease in Portugal prior to and after the introduction of pneumococcal heptavalent conjugate vaccine

The rates of invasive pneumococcal disease (IPD), serotype distribution and antimicrobial susceptibility prior to and after the introduction of the heptavalent pneumococcal conjugate vaccine in Portuguese children were evaluated. The changes in incidence of IPD in children under 1 year old between the two periods of the study was not significant (P=0.53), despite the 21% decline. In children under 18 years old there was a 27.7% decrease in vaccine serotypes. All nonvaccine serotypes increased 71.4%. The decrease in vaccine serotypes was more impressive during the first year of life (-54.8%) than for children between 1 and 5 years of age (-19.1%). Among children under 1 year old, penicillin nonsusceptible isolates declined between the two periods of the study (47.2% vs. 25.0%) (P=0.03), as did those of cefotaxime and ceftriaxone nonsusceptible isolates. No changes were observed for isolates nonsusceptible to tetracycline and macrolides. The serotypes of these nonsusceptible isolates differed after the introduction of vaccine (P=0.01). Multiresistance increased 57.1% after the introduction of vaccine. Multiresistant isolates with vaccine serotype declined 42.9% (P<0.001), and nonvaccine serotypes appeared during the vaccination period (P<0.001). These findings suggest a replacement of vaccine serotypes by nonvaccine serotypes, mainly among nonsusceptible isolates.     

Uptake of extracellular DNA: Competence induced pili in natural transformation of Streptococcus pneumoniae

Transport of DNA across bacterial membranes involves complex DNA uptake systems. In Gram‐positive bacteria, the DNA uptake machinery shares fundamental similarities with type IV pili and type II secretion systems. Although dedicated pilus structures, such as type IV pili in Gram‐negative bacteria, are necessary for efficient DNA uptake, the role of similar structures in Gram‐positive bacteria is just beginning to emerge. Recently two essentially very different pilus structures composed of the same major pilin protein ComGC were proposed to be involved in transformation of the Gram‐positive bacterium Streptococcus pneumoniae – one is a long, thin, type IV pilus‐like fiber with DNA binding capacity and the other one is a pilus structure that was thicker, much shorter and not able to bind DNA. Here we discuss how competence induced pili, either by pilus retraction or by a transient pilus‐related opening in the cell wall, may mediate DNA uptake in S. pneumoniae.