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Feeding of infant formula using contaminated bottles may be an important transmission pathway of enteric pathogens during early life. Determinants of suboptimal bottle hygiene and the feasibility and acceptability of intervention strategies have not been well assessed. We evaluated the extent of bottle contamination, its contributing factors, and options for promoting improved bottle hygiene in a Peruvian shantytown. During Phase 1, we sampled from bottles and caregiver hands (n = 48) and processed for enumeration of total coliform and Escherichia coli colony-forming units. A semi-structured questionnaire captured bottle use and hygiene practices. Phase 2 involved the identification of candidate practices to recommend to caregivers. Phase 3 consisted of a behavioral trial in which 14 caregivers were educated about improved practices for bottle disinfection and later reported on their experiences implementing them. Fecal bacteria were detected in 43.8% of bottles sampled during Phase 1 and in 21.7% of hands. Caregivers overall did not use effective methods for disinfecting bottles, displayed misunderstandings surrounding hygienic practices, and few had ever discussed bottle hygiene with a health provider. Findings from the behavioral trial indicated that the improved practice of brushing the bottle with dish detergent for 30 seconds after every use is preferable to boiling the bottle for several minutes daily as caregivers reported that the brush was simple to use, efficient, and practical. The promotion of a bottle brush and detergent is a feasible and acceptable intervention strategy in peri-urban settings, and future research should evaluate its long-term effectiveness for reducing bottle contamination.

The efficiency of ultraviolet (UV) disinfection and the regrowth potential of total coliforms were investigated in humic waters. Experiments were conducted according to an experimental design in which a UV radiation dose range of 68-681 mW s/cm(2) was applied to waters containing various concentrations (0-10 mg/L) of fulvic acid. Experimental results strongly suggested that the harmful effect of UV radiation on bacteria was diminished in humic waters due to absorption of UV light. Increasing concentrations of fulvic acid appeared to enhance its influence with elevated doses of UV radiation. Measured inactivation responses were on the order of 1-6 log(10) units for the UV dose range used. Comparison of k (inactivation coefficient) values for nonhumic water to highly humic water indicated that k decreased proportionally as the fulvic acid concentration of water was increased. The results of dark-incubation tests indicated significant regrowth of bacteria in fulvic acid-containing waters.

In this study, the possibility of using lignite fly ash in low doses for reducing the pathogen levels in wastewater sludge was investigated. The results showed that using fly ash alone in doses of 40%, 80% and 120% (on a dry weight basis), did not produce an alkaline environment for an efficient removal of pathogens. However, using fly ash in conjunction with the minimum amount of quicklime may act as an effective way of fecal coliform removal in both alkaline stabilisation and pasteurisation processes. It was shown that using fly ash in doses of 80% and 120% in alkaline stabilisation and pasteurisation processes prevented the pH decays and regrowth of pathogens during 60 days of storage period. The results of the study confirmed that alkaline pasteurisation process produces a product which is more resistant to pH decays and regrowth of fecal coliforms compared to that of alkaline stabilisation. Consequently, the overall results of this study indicated that the minimum lime and fly ash dosages required to generate a Class B biosolid were 10-15% and 80%, respectively. On the other hand, heating sludge to 50°C prior to the addition of 10-15% quicklime and 80% fly ash followed by further heating to 70°C and then sustaining at this temperature for 30 minutes were sufficient to generate a Class A biosolid.

Citrobacter rodentium is a natural mouse pathogen widely used as a model for enteropathogenic and enterohemorrhagic Escherichia coli infections in humans. While C. rodentium causes self-limiting colitis in most inbred mouse strains, it induces fatal diarrhoea in susceptible strains. The physiological pathways as well as the genetic determinants leading to susceptibility have remained largely uncharacterized. Here we use a forward genetic approach to identify the R-spondin2 gene as a major determinant of susceptibility to C. rodentium infection. Robust induction of R-spondin2 expression during infection in susceptible mouse strains causes a potent Wnt-mediated proliferative response of colonic crypt cells, leading to the generation of an immature and poorly differentiated colonic epithelium with deficiencies in ion-transport components. Our data demonstrate a previously unknown role of R-spondins and Wnt signalling in susceptibility to infectious diarrhoea and identify R-spondin2 as a key molecular link between infection and intestinal homoeostasis. © 2013 Macmillan Publishers Limited. All rights reserved.

Bioprocesses conducted under conditions with restricted O2 supply are increasingly exploited for the synthesis of reduced biochemicals using different biocatalysts. The model facultative anaerobe Escherichia coli has elaborate sensing and signal transduction mechanisms for redox control in response to the availability of O2 and other electron acceptors. The ArcBA two-component system consists of ArcB, a membrane-associated sensor kinase, and ArcA, the cognate response regulator. The tripartite hybrid kinase ArcB possesses a transmembrane, a PAS, a primary transmitter (H1), a receiver (D1), and a phosphotransfer (H2) domain. Metabolic fluxes were compared under anoxic conditions in a wild-type E. coli strain, its ΔarcB derivative, and two partial arcB deletion mutants in which ArcB lacked either the H1 domain or the PAS-H1-D1 domains. These analyses revealed that elimination of different segments in ArcB determines a distinctive distribution of D-glucose catabolic fluxes, different from that observed in the ΔarcB background. Metabolite profiles, enzyme activity levels, and gene expression patterns were also investigated in these strains. Relevant alterations were observed at the P-enol-pyruvate/pyruvate and acetyl coenzyme A metabolic nodes, and the formation of reduced fermentation metabolites, such as succinate, D-lactate, and ethanol, was favored in the mutant strains to different extents compared to the wild-type strain. These phenotypic traits were associated with altered levels of the enzymatic activities operating at these nodes, as well as with elevated NADH/NAD+ ratios. Thus, targeted modification of global regulators to obtain different metabolic flux distributions under anoxic conditions is emerging as an attractive tool for metabolic engineering purposes. © 2012, American Society for Microbiology. Fil:Ruiz, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:de Almeida, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Méndez, B.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Phasins (PhaP) are proteins normally associated with granules of poly(3-hydroxybutyrate) (PHB), a biodegradable polymer accumulated by many bacteria as a reserve molecule. These proteins enhance growth and polymer production in natural and recombinant PHB producers. It has been shown that the production of PHB causes stress in recombinant Escherichia coli, revealed by an increase in the concentrations of several heat stress proteins. In this work, quantitative reverse transcription (qRT)-PCR analysis was used to study the effect of PHB accumulation, and that of PhaP from Azotobacter sp. strain FA8, on the expression of stress-related genes in PHB-producing E. coli. While PHB accumulation was found to increase the transcription of dnaK and ibpA, the expression of these genes and of groES, groEL, rpoH, dps, and yfiD was reduced, when PhaP was coexpressed, to levels even lower than those detected in the non-PHB-accumulating control. These results demonstrated the protective role of PhaP in PHB-synthesizing E. coli and linked the effects of the protein to the expression of stress-related genes, especially ibpA. The effect of PhaP was also analyzed in non-PHBsynthesizing strains, showing that expression of this heterologous protein has an unexpected protective effect in E. coli, under both normal and stress conditions, resulting in increased growth and higher resistance to both heat shock and superoxide stress by paraquat. In addition, PhaP expression was shown to reduce RpoH protein levels during heat shock, probably by reducing or titrating the levels of misfolded proteins. © 2011, American Society for Microbiology. Fil:Catone, M.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Pettinari, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Bioreactor cultures of Escherichia coli recombinants carrying phaBAC and phaP of Azotobacter sp. FA8 grown on glycerol under low-agitation conditions accumulated more poly(3-hydroxybutyrate) (PHB) and ethanol than at high agitation, while in glucose cultures, low agitation led to a decrease in PHB formation. Cells produced smaller amounts of acids from glycerol than from glucose. Glycerol batch cultures stirred at 125 rpm accumulated, in 24 h, 30.1% (wt/wt) PHB with a relative molecular mass of 1.9 MDa, close to that of PHB obtained using glucose. Copyright © 2010, American Society for Microbiology. All Rights Reserved. Fil:De Almeida, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Pettinari, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Ice cream is a food commodity consumed widely during summer. The aim of this research is to determine the microbiological contamination sources during ice cream production. The samples were collected from four different pastry shops in Denizli area in Turkey. Samples were taken for microbial analyses from six points (premix, fresh ice cream, sold ice cream, ice cream cabinet, firming dish, scoop water and the hands of factory and sales department personnel). The results showed that premix had low levels of coliforms, Staphylococcus aureus, total aerobic mesophilic bacteria (TAMB) and yeast and mould. The levels of these microorganisms were higher in the fresh ice cream than their corresponding premixes. Moreover, sold ice cream had the highest levels of all microorganism groups. The samples taken from ice cream cabinet and firming dishes contained low levels of TAMB and yeast-mould but no coliform, faecal coliform or S. aureus. On the contrary, high levels of coliforms, faecal coliform and S. aureus, TAMB and yeast-mould were found in the samples collected from factory/sales department personnel hands and scoop water. Overall results showed that cooling method, personnel hands and scoop water were the main sources of the microbial contamination of ice cream produced and sold in pastry shops. © 2003 Elsevier Ltd. All rights reserved.

In this study, frozen anchovies (Engraulis enchrasicholus), which were going to be used for marination, were dissolved and cleared from heads, inner organs and fishbones, and then were ripened in marination solution with 4% acidity and 7.5% salt content at 4°C for 24 h. After marination, anchovies were processed with different vegetable additives and sauces including marinaded garlic, pasteurized hot pepper sauce, marinaded green olive with toothpick. Then, they were vacuum packed, stored at 4°C for 24 h. Samples were taken from these marinated anchovy fillets, and were examined microbiologically for total mesophilic aerobic bacteria, coliforms, coagulase positive staphylococci, Salmonella spp., sulfite reducing anaerobic bacteria, yeast and mold; and chemically for pH, total acidity and total salt content. In addition, ingredients and materials used for processing anchovy fillets after marination process such as vegetable additives, sauce and toothpick, were also examined microbiologically. Our results revealed that vegetable additives and sauces had no adverse effects on the microbiological quality of the final product and the anchovy fillets carried no pathogenic microorganisms that might danger public health. Therefore, we conclude that marinated anchovies are safe for consumption, if they are stored under proper conditions.

In this study, which was conducted to detect the critical control points and to investigate the direct and cross-contamination sources in white pickled cheese production, 21 control points were examined for aerobe mesophilic counts, staphylococcus-micrococcus, coagulase-positive staphylococcus, enterobacteriaceae, coliform bacteria, E. coli, enterococcus, yeast and mould counts. It was determined that the high microbiological load of raw milk affected the microbiological quality of pasteurized milk negatively, and that the production pipe-line after pasteurization, and equipment such as vats, plastic wraps, pressing cloths. starter culture and the hands of the workers, were direct contamination sources. In addition, the hands of workers and the water used in the facility played a role in direct and cross contamination, and the air in the facility was a critical control point for yeast and mould contamination.