猪源肠球菌的分离及生物特性的初报

本研究从猪粪便中分离了肠球菌两珠,经菌种鉴定两珠菌均为屡肠球菌。其生物特性的研究表明：可耐受15的胆盐和6％NaCI高盐,在pH3．0条件下可存活,对绝大多数抗生素耐药。     

Effects of low temperature, cold shock, and various carbon sources on esterase and lipase activities and exopolysaccharide production by a psychrotrophic Acinetobacter sp

The activities of isocitrate lyase, esterase, and lipase by the psychrotrophic Acinetobacter sp. strain HH1-1 were monitored during incubation at 25 degreesC, 5 degreesC, and after a 25 degreesC to 5 degreesC down shift in growth temperature. During growth at 25 degreesC, isocitrate lyase activity was detected in cell-free extracts, but at 5 degreesC and after cold shock, activity was measured primarily in the cell culture supernatant. Strain HH1-1 produced two cell-associated esterases and an extracellular esterase and lipase. Activities of the extracellular esterase and lipase were reduced when cells were grown at 5 degreesC and after cold shock. In contrast, an increased synthesis of a 53-kDa cell-associated esterase was observed 50 h after cold shock. An extracellular polysaccharide was also produced, indicated by a decrease in surface tension in cell culture supernatant when cells were incubated at 25 degreesC; but like extracellular enzyme activity, production of the exopolymer was reduced when cells were subjected to low temperatures. These results indicated that the intracellular enzyme, isocitrate lyase, leaked out of the cell after cold shock and during growth at 5 degreesC. The increased activity of a cell-associated esterase suggested this enzyme is required for growth at low temperatures. In contrast, activities of extracellular lipolytic enzymes and production of an extracellular polysaccharide were negatively affected at the lower temperatures.     

Replacing the general energy-coupling proteins of the phospho-enol-pyruvate: sugar phosphotransferase system of Salmonella typhimurium with fructose-inducible counterparts results in the inability to utilize nonphosphotransferase system sugars

A Salmonella typhimurium mutant lacking Enzyme I and HPr, general proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), but producing homologues EI(Fructose) and FPr constitutively, did not grow in minimal medium supplemented with non-PTS sugars (melibiose, glycerol, and maltose) in the absence of any trace of Luria-Bertani broth; adding cyclic AMP allowed growth. On melibiose, rapid growth began only when melibiose permease activity had reached a threshold level. Wild-type cultures reached this level within about 2 h, but the mutant only after a 12-14 h lag period, and then only when cyclic AMP had been added to the medium. On a mixture of melibiose and a PTS sugar, permease was undetectable in either the wild type or mutant until the PTS sugar had been exhausted. Permease then appeared, increasing with time, but in the mutant it never reached the threshold allowing rapid growth on melibiose unless cyclic AMP had been added. On rich medium supplemented with melibiose or glycerol, the mutant produced lower (30%) levels of melibiose permease or glycerol kinase compared with the wild type. We propose that poor phosphorylation of the regulatory protein Enzyme IIA(Glucose), leading to constitutive inducer exclusion and catabolite repression in this strain, accounts for these results.     

Clinical patterns in asthma based on proximal and distal airway nitric oxide categories

Background

The exhaled nitric oxide (eNO) signal is a marker of inflammation, and can be partitioned into proximal [J''aw_NO (nl/s), maximum airway flux] and distal contributions [CA_NO (ppb), distal airway/alveolar NO concentration]. We hypothesized that J''aw_NO and CA_NO are selectively elevated in asthmatics, permitting identification of four inflammatory categories with distinct clinical features.

Methods

In 200 consecutive children with asthma, and 21 non-asthmatic, non-atopic controls, we measured baseline spirometry, bronchodilator response, asthma control and morbidity, atopic status, use of inhaled corticosteroids, and eNO at multiple flows (50, 100, and 200 ml/s) in a cross-sectional study design. A trumpet-shaped axial diffusion model of NO exchange was used to characterize J''aw_NO and CA_NO.

Results

J''aw_NO was not correlated with CA_NO, and thus asthmatic subjects were grouped into four eNO categories based on upper limit thresholds of non-asthmatics for J''aw_NO (≥ 1.5 nl/s) and CA_NO (≥ 2.3 ppb): Type I (normal J''aw_NO and CA_NO), Type II (elevated J''aw_NO and normal CA_NO), Type III (elevated J''aw_NO and CA_NO) and Type IV (normal J''aw_NO and elevated CA_NO). The rate of inhaled corticosteroid use (lowest in Type III) and atopy (highest in Type II) varied significantly amongst the categories influencing J''aw_NO, but was not related to CA_NO, asthma control or morbidity. All categories demonstrated normal to near-normal baseline spirometry; however, only eNO categories with increased CA_NO (III and IV) had significantly worse asthma control and morbidity when compared to categories I and II.

Conclusions

J''aw_NO and CA_NO reveal inflammatory categories in children with asthma that have distinct clinical features including sensitivity to inhaled corticosteroids and atopy. Only categories with increase CA_NO were related to poor asthma control and morbidity independent of baseline spirometry, bronchodilator response, atopic status, or use of inhaled corticosteroids.     

石耳科(子囊菌亚门)的间断分布和替代现象

本文报道了石耳科的两个亚洲的,也是美洲以外的新记录种,即角石耳与深色石耳。进一步证实了单果石耳在南大西洋的,即南美洲和南部非洲的间断分布。对于上述种类以及本科其它一些种类的间断分布和替代现象进行了分析讨论。     

Microbial decomposition of leaf material at 0°C

The microbial decomposition of leaves (both fresh and autumnshed) at 0°C using stream sediment-water was investigated. The maximum rates of loss of leaf carbohydrate and protein at 0°C were considerable, being about 40% of those at 20°C. These rates were only slightly affected by the type of leaf material present being 1.3-fold higher with fresh leaves as compared with autumn-shed leaves. In addition, an epifluorescence microscopic counting technique was developed and utilized to enumerate the microbial populations colonizing the decomposing leaves. The average microbial densities on fresh and autumn-shed leaves after 35 days of incubation were 1.3 × 10⁶ and 9.0 × 10⁵ microorganisms cm^?2 at 0°C as compared with 5.5 × 10⁶ and 3.3 × 10⁶ microorganisms cm^?2 at 20°C, respectively. Antibacterial and antifungal antibiotics were used to estimate the comparative involvement of sediment bacteria and fungi in leaf degradation.     

Aerobic acetylene utilization by stream sediment and isolated bacteria

Current Microbiology - Acetylene (C2H2) uptake by stream sediment and by washed cell suspensions of an enrichment culture in the presence of air was studied. Complete disappearance of added C2H2...     

A rapid, simple method for staining bacterial flagella.

A simple modification of Gray's flagellar staining procedure is described. It can be used on air-dried smears or directly on wet mounts of motile bacteria. The stained bacterial flagella can be observed with phase-contrast or bright-field optics. No rigorous cleaning of slides, counterstains, or any washing procedures are required with the staining method, making it very suitable for routine examinations.