Detection of Metabolic Key Enzymes of Methane Turnover Processes in Cold Seep Microbial Biofilms

In anoxic environments, methane oxidation is conducted in a syntrophic process between methanotrophic archaea (ANME) and sulfate reducing bacteria (SRB). Microbial mats consisting of ANME, SRB and other microorganisms form methane seep-related carbonate buildups in the anoxic bottom waters of the Black Sea Crimean shelf. To shed light on the localization of the biochemical processes at the level of single cells in the Black Sea microbial mats, we applied antibody-based markers for key enzymes of the relevant metabolic pathways. The dissimilatory adenosine-5′-phosphosulfate (APS) reductase, methyl-coenzyme M reductase (MCR) and methanol dehydrogenase (MDH) were selected to localize sulfate respiration, reverse methanogenesis and aerobic methane oxidation, respectively. The key enzymes could be localized by double immunofluorescence and immunocytochemistry at light- and electron microscopic levels. In this study we show that sulfate reduction is conducted synchronized and in direct proximity to reverse methanogenesis of ANME archaea. Microcolonies in interspaces between ANME/SRB express methanol dehydrogenase, which is indicative for oxidation of C₁ compounds by methylotrophic or methanotrophic bacteria. Thus, in addition to syntrophic AOM, oxygen-dependent processes are also conducted by a small proportion of the microbial population.     

Evaluation of Aerated Steam Treatment of Alfalfa and Mung Bean Seeds To Eliminate High Levels of Escherichia coli O157:H7 and O178:H12, Salmonella enterica,and Listeria monocytogenes

Sprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated with Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Weltevreden, and Listeria monocytogenes Scott A. In addition, a recently collected E. coli O178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations of E. coli O157:H7 and S. enterica on alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies. L. monocytogenes and E. coli O178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).     

Q Fever Knowledge,Attitudes and Vaccination Status of Australia’s Veterinary Workforce in 2014

Q fever, caused by Coxiella burnetii, is a serious zoonotic disease in humans with a worldwide distribution. Many species of animals are capable of transmitting C. burnetii, and consequently all veterinary workers are at risk for this disease. An effective Q fever vaccine has been readily available and used in Australia for many years in at-risk groups, and the European Centre for Disease Prevention and Control has recently also called for the use of this vaccine among at-risk groups in Europe. Little is known about attitudes towards this vaccine and vaccine uptake in veterinary workers. This study aimed to determine the Q fever vaccination status of veterinarians and veterinary nurses in Australia and to assess and compare the knowledge and attitudes towards Q fever disease and vaccination of each cohort. An online cross-sectional survey performed in 2014 targeted all veterinarians and veterinary nurses in Australia. Responses from 890 veterinarians and 852 veterinary nurses were obtained. Binary, ordinal and multinomial logistic regression were used to make comparisons between the two cohorts. The results showed that 74% of veterinarians had sought vaccination compared to only 29% of veterinary nurses. Barriers to vaccination among those not vaccinated did not differ between cohorts, and included a lack of perceived risk, financial expense, time constraints, and difficulty in finding a vaccine provider. Poor knowledge and awareness of Q fever disease and vaccination were additional and notable barriers for the veterinary nursing cohort, suggesting veterinary clinics and veterinarians may not be meeting their legal responsibility to educate staff about risks and risk prevention. Further evaluation is needed to identify the drivers behind seeking and recommending vaccination so that recommendations can be made to improve vaccine uptake.     

Mapping the Influence of Food Waste in Food Packaging Environmental Performance Assessments

Scrutiny of food packaging environmental impacts has led to a variety of sustainability directives, but has largely focused on the direct impacts of materials. A growing awareness of the impacts of food waste warrants a recalibration of packaging environmental assessment to include the indirect effects due to influences on food waste. In this study, we model 13 food products and their typical packaging formats through a consistent life cycle assessment framework in order to demonstrate the effect of food waste on overall system greenhouse gas (GHG) emissions and cumulative energy demand (CED). Starting with food waste rate estimates from the U.S. Department of Agriculture, we calculate the effect on GHG emissions and CED of a hypothetical 10% decrease in food waste rate. This defines a limit for increases in packaging impacts from innovative packaging solutions that will still lead to net system environmental benefits. The ratio of food production to packaging production environmental impact provides a guide to predicting food waste effects on system performance. Based on a survey of the food LCA literature, this ratio for GHG emissions ranges from 0.06 (wine example) to 780 (beef example). High ratios with foods such as cereals, dairy, seafood, and meats suggest greater opportunity for net impact reductions through packaging‐based food waste reduction innovations. While this study is not intended to provide definitive LCAs for the product/package systems modeled, it does illustrate both the importance of considering food waste when comparing packaging alternatives, and the potential for using packaging to reduce overall system impacts by reducing food waste.     

Host genetic requirements for DNA release of lactococcal phage TP901-1

The first step in phage infection is the recognition of, and adsorption to, a receptor located on the host cell surface. This reversible host adsorption step is commonly followed by an irreversible event, which involves phage DNA delivery or release into the bacterial cytoplasm. The molecular components that trigger this latter event are unknown for most phages of Gram-positive bacteria. In the current study, we present a comparative genome analysis of three mutants of Lactococcus cremoris 3107, which are resistant to the P335 group phage TP901-1 due to mutations that affect TP901-1 DNA release. Through genetic complementation and phage infection assays, a predicted lactococcal three-component glycosylation system (TGS) was shown to be required for TP901-1 infection. Major cell wall saccharidic components were analysed, but no differences were found. However, heterologous gene expression experiments indicate that this TGS is involved in the glucosylation of a cell envelope-associated component that triggers TP901-1 DNA release. To date, a saccharide modification has not been implicated in the DNA delivery process of a Gram-positive infecting phage.     

Production of yoghurt with mild taste by a Lactobacillus delbrueckii subsp. bulgaricus mutant with altered proteolytic properties

In this communication, we describe the isolation of a Lactobacillus delbrueckii subsp. bulgaricus 92063 mutant strain named pH-P11, which differed from the parent strain by low proteolytic activity and altered regulation of expression of lacZ in the presence of glucose or lactose. In the presence of lactose, beta-galactosidase activity was approximately twice as high in pH-P11 than in the wild type. pH-P11 exhibited protosymbiosis together with Streptococcus thermophilus. Yoghurt produced with pH-P11 was characterized by low acidity and little post-acidification during storage. The organoleptic properties (absence of bitterness and other off-flavors, weak sourness, and clear yoghurt taste) were those of a typical "yoghurt mild". This mild flavor was achieved at rather high cell counts of lactobacilli even at the end of shelf-life. High cell counts in conjunction with high beta-galactosidase activity make pH-P11 an interesting strain for application in yoghurt especially designed for consumers with lactose malabsorption. In contrast to "yoghurt mild", which is predominantly produced with Lactobacillus acidophilus together with Streptococcus thermophilus, the product obtained by fermentation with pH-P11 and Streptococcus thermophilus concurs with international standards for yoghurt. During frequent sub-culturing, strain pH-P11, which is supposed to differ from the wild type by one or a few so-far-not-characterized mutations, showed sufficient stability for application in industrial production.     

Electrophoretic mobility of DNA in gels. III. Experimental study on band inversion

A series of experiments has been undertaken to study the phenomenon of band inversion that can occur during the separation of linear double-stranded DNA in agarose gels under constant electric field. We found that there can be a considerable band inversion when the DNA fragments are moving as a single species. When separating mixtures of fragments, as it is usually done in routine experiments, the band inversion effect is strongly reduced. Our data support the assumption that DNA–DNA interactions can play an important role in electrophoretic separations. © 1995 John Wiley & Sons, Inc.