Bacteriocins of gram-positive bacteria.

Bacteriocins are bacterially produced antimicrobial peptides with narrow or broad host ranges. Many bacteriocins are produced by food-grade lactic acid bacteria, a phenomenon which offers food scientists the possibility of directing or preventing the development of specific bacterial species in food. This can be particularly useful in preservation or food safety applications, but also has implications for the development of desirable flora in fermented food. In this sense, bacteriocins can be used to confer a rudimentary form of innate immunity to foodstuffs, helping processors extend their control over the food flora long after manufacture.

Bacteriocins: developing innate immunity for food

Lactic acid bacteria produce a variety of bacteriocins that have recently come under detailed investigation. The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.

Genetics of bacteriocins produced by lactic acid bacteria

http://www.dejongeakademie.nl/shared/resources/documents/bacteriocins-safe-for-food-preservation-cleveland-1.pdf

Bacteriocins: Safe, natural antimicrobials for food preservation

Vision for Transformation Strengths: The SHSIP describes a holistic transformation plan and ensures connections between various plan components. The State’s Plan seeks to reward health care providers for better care, smarter spending, and healthier people through higher quality, instead of quantity of services by utilizing valuebased purchasing across public and private payers. The SHSIP provides a well-detailed description of the proposed value-based models of care through the Patient-Centered Medical Home (PCMH) model, resulting in the statewide implementation of Accountable Health Communities (AHCs). The SHSIP outlines a long-term vision of building and expanding the PCMH model into a Community Centered Health Homes (CCHHs) model, which will focus on prevention and collaboration with other communitybased organizations. Another strength identified is the amount of existing PCMHs operating within the State. The SHSIP provides a course of action to assist non-PCMH practices to become nationally certified, as well as, goals for a single, statewide PCMH model to be used by all providers and payers within the state. The implementation of the AHCs will be key in addressing social determinants of health within various communities and seems to align well with the PCMH goals. This focus on population and community health will enable the State to make a broader impact and support the long-term goal of moving towards a CCHH model. The focus on the improvement of clinical, behavioral, and oral health care within the urban, rural, and frontier communities is well aligned and consistent with the SIM goals and the overall Triple Aim initiative. Figure 18: Driver Diagram clearly shows how the State plans to achieve the Triple Aim by 2020.

Department of health & human services

Mutational, nucleotide sequence, and transcriptional analyses of a 10-kb fragment (carnobacteriocin locus) from the 61-kb plasmid of Carnobacterium piscicola LV17B demonstrated the presence of two gene clusters (cbnXY and cbnSKRTD) upstream of the previously sequenced carnobacteriocin B2 structural and immunity genes (cbnB2 and cbiB2). Deduced products of cbnK and cbnR have sequence similarity to proteins of Agr-type two-component signal transduction systems, and those of cbnT and cbnD have sequence similarity to proteins of signal sequence-independent secretion systems. Deduced products of cbnX, cbnY, and cbnS are class II-type bacteriocin precursors with potential leader peptides containing double-glycine cleavage sites. Genetic analysis indicated that the 10-kb locus contains information required for the production of, and immunity to, the plasmid-encoded carnobacteriocin B2 and the chromosomally encoded carnobacteriocin BM1. In addition, this locus is involved in the production of at least one additional antimicrobial compound and an inducer factor that plays a role in the regulation of carnobacteriocin B2. Transcription analysis indicated that the operons cbnXY, cbnB2-cbiB2, and cbnBM1-cbiBM1 (with the latter encoding carnobacteriocin BM1 and its immunity protein on the chromosome) and two small transcripts containing cbnS are transcribed only in induced cultures. These transcripts are coregulated and subject to inducer-mediated transcriptional control. Similar regulation of the cbn operons is mirrored by the similarity in the nucleotide sequence of their promoter regions, all of which contain two imperfect direct repeats resembling those in Agr-like regulated promoters upstream of the transcription start sites.

Characterization of a Locus from Carnobacterium piscicola LV17B Involved in Bacteriocin Production and Immunity

Microcin N is a low-molecular weight, highly active antimicrobial peptide produced by uropathogenic E. coli . In this study, the native peptide was expressed and purified from pGOB18 plasmid carrying E. coli in low yield. The pure peptide was characterized using mass spectrometry, N-terminal sequencing by Edman degradation as well as trypsin digestion. We found that the peptide is 74-residue long, cationic (+2 total charge), highly hydrophobic, and consists of glycine as the first N-terminal residue. The minimum inhibitory concentration (MIC) of the peptide against Salmonella enteritidis was found to be 150 nM. Evaluation of the solution conformation of the peptide using circular dichroism spectroscopy showed that the peptide is well folded in 40% trifluoroethanol with helical structure whereas the folded structure is lost in aqueous solution. In order to increase the yield of this potent peptide, we overexpressed GST-tagged microcin N using E. coli BL21. Recombinant GST-tagged microcin N was successfully expressed in E. coli BL21, however, the cleaved mature microcin N did not show activity against the indicator strain ( Salmonella enterica ) most likely due to the extreme hydrophobic nature of the peptide. Efforts to produce active microcin N in large scale are discussed as this peptide has huge potential to be the next generation antimicrobial agent.

Characterization of a highly potent antimicrobial peptide microcin N from uropathogenic Escherichia coli.

Presumptive Escherichia coli counts for 312 samples of non-frozen ground beef were determined and compared with proposed Canadian standards. Results for frozen pork sausages, packaged at manufactur...

Michael E. Stiles

Papers

Characterization of a Locus from Carnobacterium piscicola LV17B Involved in Bacteriocin Production and Immunity

Characterization of a highly potent antimicrobial peptide microcin N from uropathogenic Escherichia coli.

Enterobacteriaceae in ground meats.

Growth and Activity of Lactococcus lactis ssp. cremoris in Ultrafiltered Skim Milk

Efficacy of Germicidal Hand Wash Agents in Use in a Meat Processing Plant.