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

Bacteriocins: Safe, natural antimicrobials for food preservation

The 3,308,274-bp sequence of the chromosome of Lactobacillus plantarum strain WCFS1, a single colony isolate of strain NCIMB8826 that was originally isolated from human saliva, has been determined, and contains 3,052 predicted protein-encoding genes. Putative biological functions could be assigned to 2,120 (70%) of the predicted proteins. Consistent with the classification of L. plantarum as a facultative heterofermentative lactic acid bacterium, the genome encodes all enzymes required for the glycolysis and phosphoketolase pathways, all of which appear to belong to the class of potentially highly expressed genes in this organism, as was evident from the codon-adaptation index of individual genes. Moreover, L. plantarum encodes a large pyruvate-dissipating potential, leading to various end-products of fermentation. L. plantarum is a species that is encountered in many different environmental niches, and this flexible and adaptive behavior is reflected by the relatively large number of regulatory and transport functions, including 25 complete PTS sugar transport systems. Moreover, the chromosome encodes >200 extracellular proteins, many of which are predicted to be bound to the cell envelope. A large proportion of the genes encoding sugar transport and utilization, as well as genes encoding extracellular functions, appear to be clustered in a 600-kb region near the origin of replication. Many of these genes display deviation of nucleotide composition, consistent with a foreign origin. These findings suggest that these genes, which provide an important part of the interaction of L. plantarum with its environment, form a lifestyle adaptation region in the chromosome.

/pdf/complete-genome-sequence-of-lactobacillus-plantarum-wcfs1-3i6pkrsthv.pdf

Complete genome sequence of Lactobacillus plantarum WCFS1

http://people.physik.hu-berlin.de/~lindner/PDF/physreport.pdf

Effects of noise in excitable systems

Large amounts of antibiotics used for human therapy, as well as for farm animals and even for fish in aquaculture, resulted in the selection of pathogenic bacteria resistant to multiple drugs. Multidrug resistance in bacteria may be generated by one of two mechanisms. First, these bacteria may accumulate multiple genes, each coding for resistance to a single drug, within a single cell. This accumulation occurs typically on resistance (R) plasmids. Second, multidrug resistance may also occur by the increased expression of genes that code for multidrug efflux pumps, extruding a wide range of drugs. This review discusses our current knowledge on the molecular mechanisms involved in both types of resistance.

Multidrug Resistance in Bacteria

Membrane proteins, lipids and detergents: not just a soap opera

Handbook of Biological Physics

In extreme environments, mainly Archaea are encountered. The archaeal cytoplasmic membrane contains unique ether lipids that cannot easily be degraded, are temperature- and mechanically resistant, and highly salt tolerant. Moreover, thermophilic and extreme acidophilic Archaea possess membrane-spanning tetraether lipids that form a rigid monolayer membrane which is nearly impermeable to ions and protons. These properties make the archaeal lipid membranes more suitable for life and survival in extreme environments than the ester-type bilayer lipids of Bacteria or Eukarya.

The essence of being extremophilic: the role of the unique archaeal membrane lipids.

Nisin is a cationic polycyclic bacteriocin secreted by some lactic acid bacteria. Nisin has previously been shown to permeabilize liposomes. The interaction of nisin was analyzed with liposomes prepared of the zwitterionic phosphatidylcholine (PC) and the anionic phosphatidylglycerol (PG). Nisin induces the release of 6-carboxyfluorescein and other small anionic fluorescent dyes from PC liposomes in a delta psi-stimulated manner, and not that of neutral and cationic fluorescent dyes. This activity is blocked in PG liposomes. Nisin, however, efficiently dissipates the delta psi in cytochrome c oxidase proteoliposomes reconstituted with PG, with a threshold delta psi requirement of about -100 mV. Nisin associates with the anionic surface of PG liposomes and disturbs the lipid dynamics near the phospholipid polar head group-water interface. Further studies with a novel cationic lantibiotic, epilancin K7, indicate that this molecule penetrates into the hydrophobic carbon region of the lipid bilayer upon the imposition of a delta psi. It is concluded that nisin acts as an anion-selective carrier in the absence of anionic phospholipids. In vivo, however, this activity is likely to be prevented by electrostatic interactions with anionic lipids of the target membrane. It is suggested that pore formation by cationic (type A) lantibiotics involves the local perturbation of the bilayer structure and a delta psi-dependent reorientation of these molecules from a surface-bound into a membrane-inserted configuration.

/pdf/mechanistic-studies-of-lantibiotic-induced-permeabilization-2w8q97r457.pdf

Mechanistic studies of lantibiotic-induced permeabilization of phospholipid vesicles.

Protons and sodium ions are the most commonly used coupling ions in energy transduction in bacteria and archaea. At their growth temperature, the permeability of the cytoplasmic membrane of thermophilic bacteria to protons is high compared with that of sodium ions. In some thermophiles, sodium is the sole energy-coupling ion. To test whether sodium is the preferred coupling ion at high temperatures, the proton- and sodium permeability was determined in liposomes prepared from lipids isolated from various bacterial and archaeal species that differ in their optimal growth temperature. The proton permeability increased with the temperature and was comparable for most species at their respective growth temperatures. Liposomes of thermophilic bacteria are an exception in the sense that the proton permeability is already high at the growth temperature. In all liposomes, the sodium permeability was lower than the proton permeability and increased with the temperature. The results suggest that the proton permeability of the cytoplasmic membrane is an important parameter in determining the maximum growth temperature.

/pdf/ion-permeability-of-the-cytoplasmic-membrane-limits-the-21bofu8lpg.pdf

Ion permeability of the cytoplasmic membrane limits the maximum growth temperature of bacteria and archaea

Picrophilus oshimae is an extremely acidophilic, thermophilic archaeon that grows optimally at 60°C and at pH 0.7. It is an obligatory acidophile that does not grow at pH values above 4.0. The proton motive force in respiring cells is composed of a large transmembrane pH gradient, inside less acid, and a reversed transmembrane electrical potential, inside positive. Cells maintain an intracellular pH at around 4.6 at extracellular pH values ranging from 0.8 to 4.0. Above pH 4.0 cells lyse rapidly and lose their viability. Liposomes prepared from lipids derived from P. oshimae have an extremely low proton permeability at acidic pH. However, at neutral pH, the lipids are unable to assemble into regular liposomal structures. These observations suggest that the loss of viability and cell integrity above pH 4.0 is due to an impairment of the barrier function of the cytoplasmic membrane.

W.N Konings

Papers

Handbook of Biological Physics

The essence of being extremophilic: the role of the unique archaeal membrane lipids.

Mechanistic studies of lantibiotic-induced permeabilization of phospholipid vesicles.

Ion permeability of the cytoplasmic membrane limits the maximum growth temperature of bacteria and archaea

Bioenergetics and cytoplasmic membrane stability of the extremely acidophilic, thermophilic archaeon Picrophilus oshimae.