60 rats were trained in a runway at 1 trial each day through 4 phases of 15 trials each. In each phase reward was either large (24 pellets) or small (2 pellets). Rats were shifted from one reward magnitude to the other in the absence of previous experience with the shift magnitude (nontransfer shift) and following experience with the shift magnitude (transfer shift). A positive contrast effect was not obtained under either condition. A negative contrast effect was obtained under nontransfer shift conditions but not under transfer shift conditions. Transfer upshifts (small reward to large) were faster than nontransfer upshifts and transfer downshifts were slower than nontransfer downshifts.

Glucan plays a central role in sucrose-dependent biofilm formation by the dental pathogen Streptococcus mutans. This organism synthesizes several proteins capable of binding glucan. These are divided into the glucosyltransferases that catalyze the synthesis of glucan and the nonglucosyltransferase glucan-binding proteins (Gbps). The biological significance of the Gbps has not been thoroughly defined, but studies suggest that these proteins influence virulence and play a role in maintaining biofilm architecture by linking bacteria and extracellular molecules of glucan. We engineered a panel of Gbp mutants, targeting GbpA, GbpC, and GbpD, in which each gene encoding a Gbp was deleted individually and in combination. These strains were then analyzed by confocal microscopy and the biofilm properties were quantified by the biofilm quantification software comstat. All biofilms produced by mutant strains lost significant depth, but the basis for the reduction in height depended on which particular Gbp was missing. The loss of the cell-bound GbpC appeared dominant as might be expected based on losing the principal receptor for glucan. The loss of an extracellular Gbp, either GbpA or GbpD, also profoundly changed the biofilm architecture, each in a unique manner.

The survival and growth of Bacillus stearothermophilus and Bacillus licheniformis, naturally present (30–300 colony forming units/ml) in late season skim milk, was monitored in a three effect evaporator during low heat skim milk powder manufacture. Substantial growth was shown to occur in the preheating stages prior to direct steam heating. A typical heat treatment (77°C, 15 s) used in the manufacture of low heat powder did not inactivate the bacteria, which continued to grow in the heater. The importance of preheaters in influencing thermophile growth in the evaporator is demonstrated by the finding that growth in the preheater stages was accompanied by growth in subsequent evaporator effects which significantly exceeded that observed when the final two preheaters were bypassed. A mid‐run mini‐clean procedure incorporating 0.2% hydrogen peroxide for decontaminating the evaporator was tested and may prove useful in extending evaporator run times

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One hundred human-derived coagulase negative staphylococci (CoNS) were screened for antimicrobial activity using agar-based deferred antagonism assays with a range of indicator bacteria. Based on the findings of the screen and subsequent well assays with cell free supernatants and whole cell extracts, one strain, designated CIT060, was selected for further investigation. It was identified as Staphylococcus capitis and herein we describe the purification and characterisation of the novel bacteriocin that the strain produces. This bacteriocin which we have named capidermicin was extracted from the cell-free supernatant of S. capitis CIT060 and purified to homogeneity using reversed-phase high performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometric (MS) analysis revealed that the capidermicin peptide has a mass of 5,464 Da. Minimal inhibitory concentration (MIC) experiments showed that capidermicin was active in the micro-molar range against all the Gram-positive bacteria that were tested. Antimicrobial activity was retained over a range of pHs (2–11) and temperatures (10–121°C x 15 mins). The draft genome sequence of S. capitis CIT060 was determined and the genes predicted to be involved in the biosynthesis of capidermicin were identified. These genes included the predicted capidermicin precursor gene, and genes that are predicted to encode a membrane transporter, an immunity protein and a transcriptional regulator. Homology searches suggest that capidermicin is a novel member of the family of class II leaderless bacteriocins.