This study aims to undertake hydroxyl ( . OH) radical-based preliminary investigations with a view to utilising seawater as a viable alternative to freshwater for the treatment of amoebic gill disease (AGD) in aquaculture industries. The study presents in vitro viability studies of clonal amoebae species to examine the effects of . OH radicals on both parasites and hosts. The study also assesses the toxicity to Chinook salmon cell lines (CHSE-214) in freshwater and 35 ppt seawater via continuous dosing of 35 mM . OH radicals and hydrogen peroxide (H 2 O 2 ) for 1.5 to 4 hr, separately at 18°C and 15°C. Comparatively high viability of CHSE-214 (60% in . OH and 50% in H 2 O 2 ) for a prolonged treatment of up to 4 hr in seawater at 15°C indicates suitability of low seawater temperature while using either . OH or H 2 O 2 during bathing. The viability of CHSE-214 remained relatively stable in seawater (55%–60% in . OH and 50%–60% in H 2 O 2 ), at both temperatures of 18°C and 15°C. However, at 15°C, a drastic reduction of viability of CHSE-214 in freshwater (from 80% to 48% in . OH and from 70% to 58% in H 2 O 2 ) has indicated high variations in toxicity levels in freshwater at low temperature. Using DNA staining agents in flow cytometry, the in vitro viability study results in >22.5% mortality of clonal Neoparamoeba perurans (NP), an AGD causative agent, in 35 ppt seawater containing 35 mM . OH radicals via one-off dosing for 1 hour at 15°C. In addition, fast radical consumption is more pronounced in the case of . OH radicals as compared to H 2 O 2 in both freshwater and seawater due to extreme reactivity of the former. Hence, this study suggests that . OH radicals are detrimental to the viability of NP in seawater, and thereby, establishes grounds for further in vivo investigations of using seawater supplemented with continuous dosing of . OH radicals for Atlantic salmon bathing as a treatment of AGD.

The rise of antibiotic resistance has increased the need for alternative ways of preventing and treating enteropathogenic bacterial infection. Various probiotic bacteria have been used in animal and human. However, Saccharomyces boulardii is the only yeast currently used in humans as probiotic. There is scarce research conducted on yeast species commonly found in kefir despite its claimed potential preventative and curative effects. This work focused on adhesion properties, and antibacterial metabolites produced by Kluyveromyces lactis and Saccharomyces unisporus isolated from traditional kefir grains compared to Saccharomyces boulardii strains. Adhesion and sedimentation assay, slide agglutination, microscopy and turbidimetry assay were used to analyze adhesion of Salmonella Arizonae and Salmonella Typhimurium onto yeast cells. Salmonella growth inhibition due to the antimicrobial metabolites produced by yeasts in killer toxin medium was analyzed by slab on the lawn, turbidimetry, tube dilution and solid agar plating assays. Alcohol and antimicrobial proteins production by yeasts in killer toxin medium were analyzed using gas chromatography and shotgun proteomics, respectively. Salmonella adhered onto viable and non-viable yeast isolates cell wall. Adhesion was visualized using scanning electron microscope. Yeasts-fermented killer toxin medium showed Salmonella growth inhibition. The highest alcohol concentration detected was 1.55%, and proteins with known antimicrobial properties including cathelicidin, xanthine dehydrogenase, mucin-1, lactadherin, lactoperoxidase, serum amyloid A protein and lactotransferrin were detected in yeasts fermented killer medium. These proteins are suggested to be responsible for the observed growth inhibition effect of yeasts-fermented killer toxin medium. Kluyveromyces lactis and Saccharomyces unisporus have anti-salmonella effect comparable to Saccharomyces boulardii strains, and therefore have potential to control Salmonella infection.

The rise of antibiotic resistance in Salmonella has necessitated the need for alternative ways of preventing and controlling infections. Fermented products have been recognised to have prophylactic and therapeutic properties against diseases. This study focused on the analysis of antagonistic effect of two different traditional kefir grains on Salmonella Arizonae and Salmonella Typhimurium after 24 and 48 h fermentation. Kefir supernatants were analysed for ethanol, organic acid and protein composition using gas chromatography, high performance liquid chromatography and shotgun proteomics, respectively. Salmonellae were rapidly eradicated in kefir possibly due to action of lactic acid as kefir cell-free supernatant contained high concentrations of lactic acid ranging from 83.59 to 229.92 mM. Other molecules with recognised antibacterial activities including carbonyl compounds, histone and cathelicidin were detected in the soluble phase that could have provided synergistic effect with the organic acids. (C) 2021 Elsevier Ltd. All rights reserved.

We establish the fact that in a continuous-flow scalable photoreactor system employed for the homogeneous photolysis of H2O2 into (OH)-O-center dot radicals, the quantum yield of photolytic conversion in aqueous solution cannot be regarded as a linear function of H2O2 initial concentration. We were successful in repeatedly producing high concentrations of (OH)-O-center dot radical (between 40 and 90 mM) from relatively low concentrations of hydrogen peroxide (between 0.1 M - 5 M) in aqueous solution in a scalable manner using our serially connected photoreactor system. Our investigation demonstrates that merely selecting a very high initial concentration of H2O2 will not necessarily result in the highest conversion into (OH)-O-center dot radical. We also developed a simple and in-situ acid-base titrimetric method for quantitation of (OH)-O-center dot radicals and demonstrated an accuracy of our method within similar to +/- 6.6% of a 31P NMR method. Hence, our proposed scalable (OH)-O-center dot radical production method via continuous flow photoreactors can be regarded as a safe, simple, accurate and cost-effective technique for various industrial processes, particularly in aquaculture and swimming pool disinfection, as a replacement of high concentrations of hazardous oxidisers.

Kefir is an acidic and low alcoholic beverage produced by fermentation of milk, fruit juice or sugary water with kefir grains and its consumption is associated with prophylactic and therapeutic properties including its antagonistic effect on enteric pathogenic bacteria. Kefir grains have several bacteria and yeast species encased in an extracellular polysaccharide matrix. The beverage is consumed due to its attributed health benefits conferred by probiotics. Kefir drink has bactericidal and bacteriostatic effects on enteric bacterial pathogens. The mechanisms of kefir on bacterial pathogens involve destabilisation of the cell membrane, cell lysis, degradation of nucleic acid, inhibition of protein synthesis and binding onto yeasts. Exopolysaccharides, organic acids, peptides, S-layer proteins, and others are responsible for these antagonistic mechanisms. Other prophylactic and therapeutic properties of kefir include anti-inflammatory, constipation-alleviating, reversal of lactose intolerance and general gastrointestinal tract improvement. This can lead to better health, and consequently resistance to infection.

Kefir is a mixed fermented product with numerous attributed health benefits due to presence of a complex culture composed of bacteria and yeasts in an exopolysaccharide matrix. This work aimed at isolating and identifying yeast species from two types of traditional kefir grains and establishing some potential probiotic properties including survival in the gastrointestinal tract, auto-aggregation, hydrophobicity and hydrolytic enzymes production. All the isolates showed good survival rates in simulated gastrointestinal tract solution, with <0.5 log10 reduction. Kluyveromyces lactis was characterized with a high level of hydrophobicity (88.75%) but moderate auto-aggregation whereas S. unisporus showed moderate hydrophobicity and auto-aggregation. Indicator enteric bacteria adhered onto both viable and non-viable yeast isolates and controls. In comparison to Saccharomyces boulardii strains used as controls, both kefir yeast strains showed low alpha hemolytic and proteolytic activities, but exhibited no phospholipase activity. Kluyveromyces lactis and Saccharomyces unisporus isolated, were identified on the basis of 26s rDNA and ITS region sequencing. Overall, the yeast isolates showed some potential probiotic properties.

Global Salmonella infection, especially in developing countries, is a health and economic burden. The use of antibiotic drugs in treating the infection is proving less effective due to the alarming rise of antibiotic-resistant strains of Salmonella, the effects of antibiotics on normal gut microflora and antibiotic-associated diarrhoea, all of which bring a growing need for alternative treatments, including the use of probiotic micro-organisms. However, there are issues with probiotics, including their potential to be opportunistic pathogens and antibiotic-resistant carriers, and their antibiotic susceptibility if used as complementary therapy. Clinical trials, animal trials and in vitro investigations into the prophylactic and therapeutic efficacies of probiotics have demonstrated antagonistic properties against Salmonella and other enteropathogenic bacteria. Nonetheless, there is a need for further studies into the potential mechanisms, efficacy and mode of delivery of yeast probiotics in Salmonella infections. This review discusses Salmonella infections and treatment using antibiotics and probiotics.

Conspicuousness towards predators may influence escape behaviour (or fearfulness') among animals, with more conspicuous species initiating escape behaviour earlier. Among birds, for example, body size and colour may influence differences in escape behaviour between species, and possibly between the sexes of dimorphic species. We examined 19 bird species with varying degrees of body size and colour dimorphism (including individually marked and sexed monomorphic species), to examine whether these two potential measures of conspicuousness influence sex differences in flight-initiation distance (FID). Starting Distance (the distance at which an observer commenced approaching a bird, which is an artefact of investigator behaviour; SD) was not correlated with dimorphism, so we used phylogenetically controlled models which explored the correlation between dimorphism and FID. Modelling indicated that only sex differences in SD correlated with sex differences in FID in these birds, and that dimorphism in either plumage or body size does not apparently correlate with sex differences in FID. These results suggest that, among the 19 bird species investigated, apparent differences in the conspicuousness to predators between the sexes do not influence escape behaviour. This suggests that either conspicuousness to predators does not influence escape distances in these species, or that sex differences in conspicuousness were too subtle to result in variation in FIDs.

CaCO3precipitation profiles, tracked by absorbance at 350 nm, showing accelerated precipitation upon exposure of the parent solutions to a pulsed electromagnetic field (PEMF) from a commercially available device.

Scaling and biofouling are two major problems in the operation of reverse osmosis (RO) membranes. A variety of control measures are employed in practice, including the use of pulsed electromagnetic fields (EMF), which can avoid the use of chemical anti-fouling agents (e.g. halogen-based biocides) that may be toxic to humans or the environment. This is a fairly recent and controversial technology and, from the available documentation and literature, it is clear that the scientific basis for its purported effectiveness is not yet firmly established, although some studies suggest that beneficial effects could be possible. In particular, the various conditions under which EMF technologies are likely to be effective for real world applications have not been scientifically established. This review collates the relevant literature on the problem of scaling and biofouling in RO membranes and heat exchangersystems (e.g. cooling towers), with a particular focus on the application of pulsed EMF technologies, including the broad documentation, relevant scientific studies, proposed mechanisms of action and further research directions. This review demonstrates that a lot more systematic scientific research is needed in order to validate the application and commercialization of EMF technologies as a pretreatment to control fouling in RO membrane systems.

BACKGROUNDPulsed-electromagnetic field (PEMF) devices are marketed and utilized for the non-chemical management of biofouling, with little scientific validation of their effectiveness. Proof-of-principle studies were carried out previously to systematically investigate the effect of two such commercial devices on the culturability of bacteria under controlled static (i.e. non-flowing) conditions and anti-microbial effects were demonstrated. However, such effects were small and an expanded investigation, using these devices and including the effect of flow, was deemed necessary. RESULTSThe effect of the electromagnetic fields generated by the same two commercial devices on the bacterial culturability of Escherichia coli and Pseudomonas fluorescens under flow conditions has been contrasted with previous static results. It has been found that the effectiveness of PEMF exposure depends on waveform, extent of flow, type of bacteria and PEMF exposure duration. CONCLUSIONBoth stimulatory and inhibitory effects are observed that are uniquely dependent upon device type (i.e. a range of parameters including waveform), species of microorganism, presence and degree of flow and PEMF exposure time. For both devices and both microorganisms, stimulatory effects are uniformly observed for one device under static conditions and inhibitory effects are uniformly observed for the other device at low flow and for the former at high flow. (c) 2017 Society of Chemical Industry

Identification of psychrotrophic pathogenic and spoilage Gram-negative bacteria using rapid and reliable techniques is important in commercial milk processing, as these bacteria can produce heat-resistant proteases and act as postprocessing contaminants in pasteurized milk. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a proven technology for identification of bacteria in food, however, may require optimization for identification of pathogenic and spoilage bacteria in milk and dairy products. The current study evaluated the effects of various culture conditions and sample preparation methods on assigning of raw milk isolates to the species level by MALDI-TOF MS. The results indicated that culture media, incubation conditions (temperature and time), and sample preparation significantly affected the identification rates of bacteria to the species level. Nevertheless, the development of spectral libraries of isolates grown on different media using a web tool for hierarchical clustering of peptide mass spectra (SPECLUST) followed by a ribosomal protein based bioinformatics approach significantly enhanced the assigning of bacteria, with at least one unique candidate biomarker peak identified for each species. Phyloproteomic relationships based on spectral profiles were compared to phylogenetic analysis using 16S rRNA gene sequences and demonstrated similar clustering patterns with significant discriminatory power. Thus, with appropriate optimization, MALDI-TOF MS is a valuable tool for species-level discrimination of pathogenic and milk spoilage bacteria.

Refrigerated storage of raw milk is a prerequisite in dairy industry. However, temperature abused conditions in the farming and processing environments can significantly affect the microbiological quality of raw milk. Thus, the present study investigated the effect of different refrigeration conditions such as 2, 4, 6, 8, 10 and 12 °C on microbiological quality of raw milk from three different dairy farms with significantly different initial microbial counts. The bacterial counts (BC), protease activity (PA), proteolysis (PL) and microbial diversity in raw milk were determined during storage. The effect of combined heating (75 ± 0·5 °C for 15 s) and refrigeration on controlling those contaminating microorganisms was also investigated. Results of the present study indicated that all of the samples showed increasing BC, PA and PL as a function of temperature, time and initial BC with a significant increase in those criteria ≥6 °C. Similar trends in BC, PA and PL were observed during the extended storage of raw milk at 4 °C. Both PA and PL showed strong correlation with the psychrotrophic proteolytic count (PPrBC: at ≥4 °C) and thermoduric psychrotrophic count (TDPC: at ≥8 °C) compared to total plate count (TPC) and psychrotrophic bacterial count (PBC), that are often used as the industry standard. Significant increases in PA and PL were observed when PPrBC and TDPC reached 5 × 104 cfu/ml and 1 × 104 cfu/ml, and were defined as storage life for quality (S LQ), and storage life for safety (S LS) aspects, respectively. The storage conditions also significantly affected the microbial diversity, where Pseudomonas fluorescens and Bacillus cereus were found to be the most predominant isolates. However, deep cooling (2 °C) and combination of heating and refrigeration (≤4 °C) significantly extended the S LQ and S Ls of raw milk.