Factors influencing attachment of thermophilic bacilli to stainless steel

AIMS: This project aimed to investigate the mechanism of attachment of the vegetative cells and spores of thermophilic bacilli to stainless steel with a view to devising strategies to limit biofilm development and survival. METHODS AND RESULTS: Spores and vegetative cells of bacterial isolates were exposed to protein denaturing agents (sodium dodecyl sulphate (SDS) and trypsin) and polysaccharide removing agents (sodium metaperiodate, trichloroacetic acid (TCA) and lysozyme). Treatment with sodium metaperiodate, TCA and lysozyme increased the number of vegetative cells attaching in many of the strains studied, while SDS and trypsin decreased attachment. Spores attached to stainless steel in greater numbers than vegetative cells, and the various treatments had less effect on this attachment than for vegetative cells. Viability of the cells or spores was not an important factor in attachment, as cells and spores rendered non-viable also attached to stainless steel in similar numbers. Coating the stainless steel with skim milk proteins decreased the attachment of both vegetative cells and spores. There was no correlation between the degree of attachment and the amount of extracellular polysaccharide (EPS) produced by each strain, surface hydrophobicity or zeta potential of vegetative cells or spores, though spores were found to be more hydrophobic than vegetative cells. CONCLUSIONS: The results suggest that biofilm formation by these thermophilic bacilli is probably a multifactorial process, and that cell-surface proteins play a very important role in the initial process of attachment during the formation of biofilms by these bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This information will provide direction for developing improved cleaning systems to control biofilms of thermophilic bacilli in dairy manufacturing plants.     

Comparison of in vitro models to study bacterial adhesion to the intestinal epithelium

Aims:  To evaluate the adhesion ability of intestinal bacteria to different in vitro models of intestinal epithelia, and to estimate the suitability of these models and the type of interactions involved.
Methods and results:  The adhesion of probiotic ( Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp . lactis Bb12), commensal ( B. animalis IATA-A2 and B. bifidum IATA-ES2) and potentially pathogenic bacteria ( E. coli and L. monocytogenes ) was determined. The adhesion models used were polycarbonate-well plates, with or without mucin, and different configurations of Caco-2 and/or HT29-MTX cell cultures. All bacteria adhered to wells without mucin (2·6–27·3%), the values being highly variable depending on the bacterial strain. Adhesion percentages of potentially probiotic bacteria to Caco-2 cultures were remarkably lower ( P  <   0·05) than those to mucin, and more similar to those of pathogenic strains. The lowest adhesion of different bacterial strains was detected on HT29-MTX (0·5–2·3%) cultures and Caco-2/HT29-MTX (0·6–3·2%) cocultures, while these values were increased in Caco-2 cultures plus mucin.
Conclusions:  The results suggested that bacterial strains exhibit different capacities to adhere to cellular components and several types of mucin present in different models, showing preferences for intestinal MUC2.
Significance and impact of the study:  The use of Caco-2 cells monolayer plus mucin (type II) better approaches the physiological characteristics of in vivo situation, providing a reliable and suitable in vitro model to evaluate bacterial adhesion.     

Issues in determining factors influencing bacterial attachment: a review using the attachment of Escherichia coli to abiotic surfaces as an example

The emergence of an increasing number of antibiotic resistant human clinical bacteria has been a great cause of concern for the last decades. As an example, Staphylococcus aureus isolates in the hospital environment are becoming more and more resistant to antibiotics including vancomycin which is considered as a last line of defence in treatment of Staphylococcus aureus -resistant methicillin. On the other hand, food safety is threatened by development of pathogenic bacteria including Listeria monocytogenes, Campylobacter jejuni, Salmonella enteritidis, Escherichia coli O157:H7 and Staphylococcus aureus. The use of antimicrobial peptides such as glycopeptides, semi-synthetic peptides, bacteriocins including lantibiotics offers a hope to face these clinical and food microbiology concerns. Clinical approval of new chemotherapeutic agents requires a long period of time. Research on bacteriocins has demonstrated potential use to fight against undesired foodborne pathogens but the use industrial use of bacteriocins is limited. To date only lantibiotic nisin and in class IIa bacteriocin Pediocin PA-1 are legally used as food preservative in many countries. The present minireview is focused on divercin V41 (DvnV41), a class IIa bacteriocin naturally produced by Carnobacterium divergens V41. The last decade has been the witness of intensive investigations carried out on this cationic peptide tempting to answer multiple questions covering basic and applied aspects. DvnV41 has shown a wide spectrum of activity either alone or in combination with nisin and/or polymixins (synergistic effect). This outcome indicates that Cb. divergens V41 could potentially be used for safe and efficient prevention of L. monocytogenes growth in cold smoked salmon.     

Comparative studies of the composition of bacterial microbiota associated with the ruminal content,ruminal epithelium and in the faeces of lactating dairy cows

The objective of this research was to compare the composition of bacterial microbiota associated with the ruminal content (RC), ruminal epithelium (RE) and faeces of Holstein dairy cows. The RC, RE and faecal samples were collected from six Holstein dairy cows when the animals were slaughtered. Community compositions of bacterial 16S rRNA genes from RC, RE and faeces were determined using a MiSeq sequencing platform with bacterial‐targeting universal primers 338F and 806R. UniFrac analysis revealed that the bacterial communities of RC, RE and faeces were clearly separated from each other. Statistically significant dissimilarities were observed between RC and faeces (P = 0.002), between RC and RE (P = 0.003), and between RE and faeces (P = 0.001). A assignment of sequences to taxa showed that the abundance of the predominant phyla Bacteroidetes was lower in RE than in RC, while a significant higher (P < 0.01) abundance of Proteobacteria was present in RE than in RC. When compared with the RC, the abundance of Firmicutes and Verrucomicrobia was higher in faeces, and RC contained a greater abundance of Bacteroidetes and Tenericutes. A higher proportions of Butyrivibrio and Campylobacter dominated RE as compared to RC. The faecal microbiota was less diverse than RC and dominated by genera Turicibacter and Clostridium. In general, these findings clearly demonstrated the striking compositional differences among RC, RE and faeces, indicating that bacterial communities are specific and adapted to the harbouring environment.     

Adrenoceptor heterogeneity in the ruminal epithelium of sheep

The pre-gastric rumen of sheep plays a crucial role in the fermentation of nutrients and in the absorption of nutrients and minerals. Adrenaline has been shown previously to increase ruminal absorption of glucose and water. The present study was intended to elucidate whether ruminal ion transport is also altered by adrenaline. In Ussing chambers, changes of I_sc were recorded in isolated ovine ruminal epithelia after the serosal additions of adrenoceptor agonists or antagonists. I_sc increased after the addition of adrenaline (10^–4 M) or clonidine (₂-agonist, 10^–4 M), but decreased after the addition of isoproterenol (-agonist, 10^–4 M) or terbutaline (₂-agonist, 10^–5 M). The effect of adrenaline on I_sc was augmented by the adrenoceptor antagonists prazosin (₁, 10^–4 M) and bupranolol (, 10^–6 M), but inversed by yohimbine (₂, 10^–5 M). Adrenaline induced an increase in Na⁺ net flux across the epithelium that was larger than the increase in equivalent current flow. It is concluded that adrenaline differentially regulates ion transport across the ruminal epithelium via ₁-, ₂-, and ₂-receptors. The main effect is a stimulation of electroneutral and electrogenic Na⁺ absorption. This stimulated Na⁺ absorption might be causative of increased water absorption from the rumen as described previously.     

影响山羊体外受精的因素

以屠宰山羊卵母细胞为材料研究了公羊个体、附睾不同部位精子、成熟培养和受精时卵丘存在与否、卵丘扩展程度及卵龄对山羊体外受精的影响。结果表明 :1)不同公羊精液在受精、卵裂和桑椹 /囊胚率上都有显著差异 ;2 )附睾尾精子和鲜精的受精、卵裂和桑椹 /囊胚率无显著差异 ,但显著高于附睾体和附睾头精子 ;3)成熟培养 2 4和 2 7h卵母细胞的的桑椹胚 /囊胚率显著高于培养 2 1和 30h卵母细胞 ;4 )卵丘扩展 3和 4级卵母细胞受精和桑椹胚 /囊胚率显著高于扩展 0和 1级卵母细胞 ;5 )成熟培养前机械去卵丘严重影响卵母细胞体外受精和桑椹胚 /囊胚率 ;6 )受精前完全去掉卵丘显著影响桑椹胚 /囊胚率     

Factors influencing the attachment strength of Dreissena polymorpha (Bivalvia)

Abstract

The effects of several factors (shell length, exposure time, substratum orientation in space, illumination, temperature, conspecifics) upon the attachment strength (measured with a digital dynamometer) of the freshwater, gregarious bivalve Dreissena polymorpha were studied under laboratory conditions. A rapid increase in attachment strength was observed on resocart (a thermosetting polymer based on phenol-formaldehyde resin, with paper as filler) substrata during the first 4-d exposure, after which it stabilised at ca 1 N. The attachment strength increased also with mussel size. Mussel adhesion on variously oriented surfaces (vertical, upper horizontal and lower horizontal) was similar. Illumination inhibited attachment strength, as expected for a photophobic species, but only after a 2-d exposure. After 6 d, no effects of light were detected. Thus, illumination seemed to influence the attachment rate, rather than the final strength. The optimum temperature for mussel attachment was 20 – 25°C. At lower and higher temperatures (5 – 15°C and 30°C), their adhesion strength decreased. The presence of conspecifics stimulated mussel attachment strength.     

Factors influencing the attachment strength of Dreissena polymorpha (Bivalvia)

The effects of several factors (shell length, exposure time, substratum orientation in space, illumination, temperature, conspecifics) upon the attachment strength (measured with a digital dynamometer) of the freshwater, gregarious bivalve Dreissena polymorpha were studied under laboratory conditions. A rapid increase in attachment strength was observed on resocart (a thermosetting polymer based on phenol-formaldehyde resin, with paper as filler) substrata during the first 4-d exposure, after which it stabilised at ca 1 N. The attachment strength increased also with mussel size. Mussel adhesion on variously oriented surfaces (vertical, upper horizontal and lower horizontal) was similar. Illumination inhibited attachment strength, as expected for a photophobic species, but only after a 2-d exposure. After 6 d, no effects of light were detected. Thus, illumination seemed to influence the attachment rate, rather than the final strength. The optimum temperature for mussel attachment was 20- 25 degrees C. At lower and higher temperatures (5-15 degrees C and 30 degrees C), their adhesion strength decreased. The presence of conspecifics stimulated mussel attachment strength.     

Factors affecting adhesion of bacterial to a tooth in vitro

The initial adhesion of oral bacteria to a tooth in vitro was examined. The organisms were grown in broth with and without sucrose, and suspensions made either in broth or a modified Ringer's solution. The tooth used was either dry or coated with natural or synthetic saliva. Adhesion was determined by counting organisms removed from the tooth surface by simple washing or by sonication. It was found that the firmest bonding occurred when a dry tooth was immersed in a suspension of bacteria in Ringer's solution; the prior growth of the organisms in the presence of sucrose did not affect adhesion. It was concluded that instantaneous irreversible adhesion of bacteria to a tooth occurs without the need for active metabolism, and that this process is inhibited by the presence of competing organic substances which probably produce a surface-conditioning film.     

Factors influencing human leukocyte adherence in vitro

Studies were performed on factors influencing leucocyte adherence in vitro. Blood condensation was found to increase leukocyte adherence. Addition of heparin, dextran or ethanol caused a significant reduction of white blood cell count in blood samples in comparison with blood mixed with sodium EDTA or ACD solution. This suggests the existence of two granulocyte subpopulations; viz, rapidly adhering and slowly adhering. Heparin enhanced granulocyte adherence, while dextran and ethanol decreased it. Five-day storage of ACD blood led to a decrease in granulocyte adherence, while addition of heparin or histamine to ACD blood prevented this change to occur. The glucose concentration of 1,000 mg/dl augmented granulocyte adherence, while higher glucose concentrations induced its progressive fall below the control values. There was no significant change of lymphocyte adherence during the experiments.     

Factors influencing the in vitro hatching of mouse blastocysts

The influence of bovine serum albumin (BSA) concentration on embryo hatching and the number of embryos cultured per drop of culture medium was examined in F1 (C57BL/6J × DBA/2J), C3HeB/FeJ strain and Line E mice. Embryos collected from F1 and Line E mice exhibited uniform hatching rates at BSA concentrations between 1 and 10 mg/ml, and embryo numbers ranging from 1 to 10 per 3 μ1 of culture medium. The hatching of C3HeB/FeJ blastocysts was greater at the higher concentrations of BSA and higher embryo densities. When the C3HeB/FeJ embryos were grown at high densities until morula and then cultured singly in fresh media they hatched at a low rate. However, when allowed to develop until the blastocyst stage before replotting, the embryos hatched at a high rate. C3HeB/FeJ embryos cultured singly until morula and then placed in groups of 10 hatched at a high rate. Single C3HeB/FeJ embryos, cultured in medium conditioned by the prior presence of embryos at high densities, hatched at a slightly higher frequency than those cultured in fresh medium. There was no tendency of embryos developing from the two-cell to the eight-cell stages to hatch when cultured in the presence of high densities of hatching blastocysts.