The shelf life of fresh fish and meat transported over long distances could be extended by using plant-based extracts to control spoilage bacteria. The goals of the present study were to identify plant-based extracts that effectively suppress the main spoilage bacteria of chilled fish and lamb and to assess their antioxidant capacity. The phenolic compounds in wood-based tannins and extracts isolated from byproducts of the fruit processing industry were identified and/or quantified. The total phenol content, but not the flavonoid to total phenol ratio, was strongly associated with higher antibacterial activity against several fish and lamb spoilage bacteria in zone of inhibition and minimum inhibitory concentration assays as well as greater antioxidant capacity in the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical assay. The most promising compounds in both cases, and thus good candidates for antibacterial packaging or antioxidant dietary supplements, were mango seed extract and tannic acid containing mostly polygalloyl glucose type phenols.

BackgroundBiofilms are formed by a complex bacterial community encapsulated by a polymeric matrix, with strong adherent properties and persistent phenotype. Biofilms are considered one of the most challenging areas of modern medicine. Existing antibiotics have been developed against free-floating bacterial cells, and thus, many treatments of biofilm-related infection fail. In this study, we compared the effects of different media on biofilm growth of clinical reference strains of Staphylococci and Enterococci, including multi-drug resistant representatives. Further, we optimized the resazurin-based assay for determining the minimal biofilm inhibitory concentration (MBIC) of standard antibiotics, and evaluated its use for the determination of minimal biofilm eradication concentration (MBEC).ResultsWe showed that tryptic soy broth supplemented with 1% glucose was an optimal media for maximum biofilm growth of all strains tested, with an extended incubation time for Enterococci. A range of parameters were tested for the resazurin assay, including concentration, temperature and time of incubation. Using quality parameters to analyze the assay’s performance, the conditions for the resazurin assay were set as follows: 4 μg/mL and 8 μg/mL, with incubation at 25 °C for 20 min and 40 min for Staphylococci and Enterococci, respectively.ConclusionsIn summary, we defined conditions for optimal biofilm growth and for standardized resazurin assay for MBIC determination against six Gram-positive clinical reference strains. We also observed that MBEC determination by the resazurin-based assay is limited due to the poor detection limit of the assay. Complementary cell counting data is needed for precise determination of MBEC.Electronic supplementary materialThe online version of this article (10.1186/s12866-018-1321-6) contains supplementary material, which is available to authorized users.

Members of the HERC (domain homologous to E6 associated protein carboxy-terminus and RCC1 domain protein) family may function both as guanine nucleotide exchange factors and E3 ubiquitin ligases. Here we identify an unstudied member, HERC3. This protein was recognized by specific antibodies in different cell types. HERC3 was located in the cytosol and in vesicular-like structures containing L L-COP, ARF and Rab5 proteins. Involvement of HERC3 in the ubiquitin system was suggested by its ability to interact with ubiquitin. The conserved cysteine in HECT proteins was not essential for this non-covalent binding. Moreover, HERC3 was a substrate of ubiquitination being degraded by the proteasome. These observations indicate a fine regulation of HERC3 and suggest a role in vesicular traffic and ubiquitin-dependent processes. ß

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bThe food-borne pathogen Vibrio parahaemolyticus has been reported as being present in New Zealand (NZ) seawaters, but there have been no reported outbreaks of food-borne infection from commercially grown NZ seafood. Our study determined the current incidence of V. parahaemolyticus in NZ oysters and Greenshell mussels and the prevalence of V. parahaemolyticus tdh and trh strains. Pacific (235) and dredge (21) oyster samples and mussel samples (55) were obtained from commercial shellfish-growing areas between December 2009 and June 2012. Total V. parahaemolyticus numbers and the presence of pathogenic genes tdh and trh were determined using the FDA most-probable-number (MPN) method and confirmed using PCR analysis. In samples from the North Island of NZ, V. parahaemolyticus was detected in 81% of Pacific oysters and 34% of mussel samples, while the numbers of V. parahaemolyticus tdh and trh strains were low, with just 3/215 Pacific oyster samples carrying the tdh gene. V. parahaemolyticus organisms carrying tdh and trh were not detected in South Island samples, and V. parahaemolyticus was detected in just 1/21 dredge oyster and 2/16 mussel samples. Numbers of V. parahaemolyticus organisms increased when seawater temperatures were high, the season when most commercial shellfish-growing areas are not harvested. The numbers of V. parahaemolyticus organisms in samples exceeded 1,000 MPN/g only when the seawater temperatures exceeded 19°C, so this environmental parameter could be used as a trigger warning of potential hazard. There is some evidence that the total V. parahaemolyticus numbers increased compared with those reported from a previous 1981 to 1984 study, but the analytical methods differed significantly. Because of the halophilic nature and marine habitat of Vibrio parahaemolyticus, raw seafood can naturally harbor this microorganism and is the main food source responsible for the gastroenteritis the microorganism causes (1). A recent report released by the U.S. Centers for Disease Control and Prevention estimated that the average annual incidence of Vibrio species infections in the United States increased by 43% from the 2006 to 2008 period to 2012 (2). The incidence rate of V. parahaemolyticus infection in New Zealand (NZ) is calculated to be 1.6/100,000, increasing to 15.3/100,000 in the Pacific Islander population, with most cases linked to imported seafood (3).An international risk assessment of V. parahaemolyticus in raw seafood highlighted the importance of exposure to raw oysters based on the incidence of V. parahaemolyticus harboring the thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh) genes at harvest (4).NZ has two main islands (Fig. 1) that extend from latitudes 34°t o 47°south. This means that there are diverse habitats and significant differences in water temperature along the length of the country, with cooler waters in the south. The first reported NZ isolation of V. parahaemolyticus was from Bay of Islands' shellfish (5). Subsequently, Fletcher (6) conducted a 3-year surve...

HERC proteins are characterized by having one or more RCC1-like domains as well as a C-terminal HECT domain in their amino acid sequences. This has led researchers to suggest that they may act as both guanine nucleotide exchange factors and E3 ubiquitin ligases. Here we describe a physical interaction between the HECT domain of HERC1, a giant protein involved in intracellular membrane tra⁄c, and the M2 isoform of glycolytic enzyme pyruvate kinase (M2-PK). Partial colocalization of endogenous proteins was observed by immuno£uorescence studies. This interaction neither induced M2-PK ubiquitination nor a¡ected its enzymatic activity. The putative signi¢cance of the association is discussed.

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