P.J. Bremer

Numbers and transported state of Escherichia coli in runoff direct from fresh cowpats under simulated rainfall

Aims:  To investigate the number of Escherichia coli in runoff derived directly from fresh cowpats and to determine if the E. coli are attached to dense particles, in flocs or as individual cells.

Evaluation of the effectiveness of a commercially available defined substrate medium and enumeration system for measuring Escherichia coli numbers in faeces and soil samples

Aims:  To determine if a commercially available defined substrate medium and enumeration system could be utilized as an effective and accurate means of enumerating Escherichia coli in environmental samples containing faeces and soil.

Adsorption of enterobactin to metal oxides and the role of siderophores in bacterial adhesion to metals.

The potential contribution of chemical bonds formed between bacterial cells and metal surfaces during biofilm initiation has received little attention. Previous work has suggested that bacterial siderophores may play a role in bacterial adhesion to metals. It has now been shown using in situ ATR-IR spectroscopy that enterobactin, a catecholate siderophore secreted by Escherichia coli, forms covalent bonds with particle films of titanium dioxide, boehmite (AlOOH), and chromium oxide-hydroxide which model the surfaces of metals of significance in medical and industrial settings. Adsorption of enterobactin to the metal oxides occurred through the 2,3-dihydroxybenzoyl moieties, with the trilactone macrocycle having little involvement. Vibrational modes of the 2,3-dihydroxybenzoyl moiety of enterobactin, adsorbed to TiO(2), were assigned by comparing the observed IR spectra with those calculated by the density functional method. Comparison of the observed adsorbate IR spectrum with the calculated spectra of catecholate-type [H(2)NCOC(6)H(3)O(2)Ti(OH)(4)](2-) and salicylate-type [H(2)NCOC(6)H(3)O(2)HTi(OH)(4)](2-) surface complexes indicated that the catecholate type is dominant. Analysis of the spectra for enterobactin in solution and that adsorbed to TiO(2) revealed that the amide of the 2,3-dihydroxybenzoylserine group reorientates during coordination to surface Ti(IV) ions. Investigation into the pH dependence of enterobactin adsorption to TiO(2) surfaces showed that all 2,3-dihydroxybenzoyl groups are involved. Infrared absorption bands attributed to adsorbed enterobactin were also strongly evident for E. coli cells attached to TiO(2) particle films. These studies give evidence of enterobactin-metal bond formation and further suggest the generality of siderophore involvement in bacterial biofilm initiation on metal surfaces.

Understanding the Needs of Food-Allergic Adults

Food allergies are a growing issue, yet society’s understanding of how individuals’ lives are affected is limited. We conducted four focus groups with food-allergic adults in New Zealand to gain an in-depth understanding of the issues that impacted their quality of life. Key themes identified included allergen-free eating issues, health care system issues, costs of having a food allergy, effects on well-being, external influences (e.g., others’ lack of awareness), and internal influences (personal growth and adaptation). The unmet needs of food-allergic adults led to risk taking, increased stress, and social isolation. A lack of awareness in others (including medical professionals, food service providers, and the general public) had a negative impact, suggesting that an intervention targeting awareness would be beneficial. Adaptation, particularly in terms of assertiveness and organizational skills, was important for coping, so we suggest training in these skills be made available for food-allergic patients.

Prediction of the amount and rate of histamine degradation by diamine oxidase (DAO)

Histamine is a biogenic amine that forms in a variety of foods and can cause food poisoning at high concentrations (>500 ppm). In situations where the formation of histamine in food cannot be prevented through refrigeration, diamine oxidase (DAO) enzyme may be used to degrade histamine to safe levels. The aims of this work were to apply DAO in model (buffer) and real (cooked tuna soup used in the manufacture of a fish paste product, Rihaakuru) systems, in order to obtain predictions for the rates and amounts of histamine degradation. The two systems were set up with a constant concentration of histamine (500 mg/L) and the DAO enzyme (2534 units/L) at a temperature of 37°C, agitation at 100 rpm and an incubation time of 10h with variable pH (5-7) and salt concentrations (1-5%). A total of 15 experiments were designed for each system using central composite design (CCD). The data from these experiments were fitted into regression models; initially the data were used to generate an exponential decline model and then the data from this were fitted into a secondary response surface model (RSM) to predict the rate and amount of histamine degradation by DAO. The model system results indicated that DAO activity was not significantly affected by salt (p>0.05), and that activity reached a maximum within the pH range of 6-6.5 with an optimum at pH 6.3. However, the results obtained with the tuna soup model showed that the optimum oxidation of histamine using DAO occurred between pH 6-7 and salt 1-3%. This study defined the conditions for the use of DAO to degrade 500 mg/L of histamine in tuna soup used to manufacture Rihaakuru. The models generated could also be used to predict the rate and amount of histamine degradation in other foods that have similar characteristics to tuna soup.

Seasonal changes in the biochemical composition of Evechinus chloroticus gonads (Echinodermata: Echinoidea)

Abstract The influence of season, gender and sexual maturity on the biochemical composition (moisture, protein, total lipids, triglycerides, cholesterol, phospholipids, free amino acids, glucose and glycogen) of gonads from the endemic New Zealand sea urchin Evechinus chloroticus was investigated. Gonads were obtained from urchins during the austral autumn, winter, summer and spring, over a 23-month period. Biochemical differences between genders were less pronounced in autumn (March to May) and winter (June to August) when more nutritive cells were present in the gonads, and more distinct over spring (September to November) and summer (December to February) months as the gametogenic cells matured, thus highlighting the importance of assessing testes and ovaries separately during biochemical analysis. Differences in the biochemical composition of testes and ovaries were the least pronounced during autumn, which suggests this will be the best season to harvest E. chloroticus in order to enhance taste and flavour, and reduce variability.

Bacteria and chromium in marine sediments

Chromium (Cr), atomic number 24 and mass 52.01, is one of the most widely used metals in industry (Stern, 1982; Kimbell and Panulas, 1984; Moore and Ramamoorthy, 1984) and its use is increasing (Papp, 1983). Since many Cr-containing effluents are discharged into bodies of water (Moore and Ramamoorthy, 1984), the possibility that the discharged Cr interacts with the biota immediately or subsequently has to be considered. From the literature there is little evidence that consideration has been given to this possibility (Moore and Ramamoorthy, 1984).

Effect of NaOH (caustic wash) on the viability, surface characteristics and adhesion of spores of a Geobacillus sp. isolated from a milk powder production line

Aim:  To investigate the viability, surface characteristics and ability of spores of a Geobacillus sp. isolated from a milk powder production line to adhere to stainless steel surfaces before and after a caustic (NaOH) wash used in clean‐in‐place regimes.

The stress of food allergy issues in daily life

Objective: Food allergies are a growing health concern, but their implications for daily psychological functioning are unknown. This micro-longitudinal study investigated the daily frequency of food allergy issues and how this related to experiences of stress, mood and physical energy. Design: One hundred and eight adults with physician-diagnosed food allergies completed an initial Internet survey followed by a 2-week Internet daily diary survey. Main outcome measures: The initial survey collected socio-demographic and food allergy information. The daily survey collected information about the participants’ experiences of stress, mood, physical energy and food allergy issues during that day. Results: Commonly experienced allergy issues included negative physical symptoms, higher food prices, anxiety about safety of food, trouble maintaining a healthy diet and anxiety/stress at social occasions. Furthermore, multilevel modelling analyses showed that stress and negative mood were significantly higher on days with more allergy issues. Older adults experienced lower positive mood and physical energy on days with more issues. Conclusion: This is the first study to incorporate near to real-time tracking to examine the frequency of food allergy issues and the implications for daily psychological functioning. Targeting the issues we identified could reduce stress in patients with food allergies and improve their overall quality of life.

Measuring textile adsorption of body odor compounds using proton-transfer-reaction mass spectrometry

This paper describes a method for determining the differential adsorption of body odor compounds by three types of yarn/fiber (cotton, polyester, wool) using proton-transfer-reaction mass spectrometry (PTR-MS). Each type exhibited different adsorption profiles. Decanal and cyclohexanone adsorbed more to wool than to either cotton or polyester. Ethylbenzene and butanoic acid methyl ester adsorbed more to polyester than to either cotton or wool. Cotton was a weaker adsorbent than polyester and wool for all odor compounds tested. Phenol was adsorbed highly by all three yarns. The study validated the use of PTR-MS to assess the adsorption of volatile compounds by textile fibers/yarns, and demonstrated its potential to be used as a rapid means of assessing the kinetics of odor adsorption and release by existing and modified materials.