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Aims The aim of this study is to evaluate the capacity of three bacteriocin producers, namely Lactococcus lactis subsp. lactis biovar diacetylactis UL719 (nisin Z producer), L. lactis ATCC 11454 (nisin A producer) and Pediococcus acidilactici UL5 (pediocin PA-1 producer), and to grow and produce their active bacteriocins in Macfarlane broth, which mimics the nutrient composition encountered in the human large intestine. Methods and Results The three bacteriocin-producing strains were grown in Macfarlane broth and in De Man- Rogosa- Sharpe ( MRS) broth. For each strain, the bacterial count, p H drop and production of organic acids and bacteriocins were measured for different period of time. The ability of the probiotic candidates to inhibit Listeria ivanovii HPB 28 in co-culture in Macfarlane broth was also examined. Lactococcus lactis subsp. lactis biovar diacetylactis UL719, L. lactis ATCC 11454 and Ped. acidilactici UL5 were able to grow and produce their bacteriocins in MRS broth and in Macfarlane broth. Each of the three candidates inhibited L. ivanovii HPB 28, and this inhibition activity was correlated with bacteriocin production. The role of bacteriocin production in the inhibition of L. ivanovii in Macfarlane broth was confirmed for Ped. acidilactici UL5 using a pediocin nonproducer mutant. Conclusions The data provide some evidence that these bacteria can produce bacteriocins in a complex medium with carbon source similar to those found in the colon. Significance and Impact of the Study This study demonstrates the capacity of lactic acid bacteria to produce their bacteriocins in a medium simulating the nutrient composition of the large intestine. [ABSTRACT FROM AUTHOR]

Background and Aims Plants are sessile organisms that face selection by both herbivores and pollinators. Herbivores and pollinators may select on the same traits and/or mediate each others' effects. Erysimum capitatum (Brassicaceae) is a widespread and variable plant species with generalized pollination that is attacked by a number of herbivores. The following questions were addressed. (a) Are pollinators and herbivores attracted by similar plant traits? (b) Does herbivory affect pollinator preferences? (c) Do pollinators and/or herbivores affect fitness and select on plant traits? (d) Do plant compensatory responses affect the outcome of interactions among plants, pollinators and herbivores? (e) Do interactions among E. capitatum and its pollinators and herbivores differ among sites and years? Methods In 2005 and 2006, observational and experimental studies were combined in four populations at different elevations to examine selection by pollinators and herbivores on floral traits of E. capitatum. Key Results Pollinator and herbivore assemblages varied spatially and temporally, as did their effects on plant fitness and selection. Both pollinators and herbivores preferred plants with more flowers, and herbivory sometimes reduced pollinator visitation. Pollinators did not select on plant traits in any year or population and E. capitatum was not pollen limited; however, supplemental pollen resulted in altered plant resource allocation. Herbivores reduced fitness and selected for plant traits in some populations, and these effects were mediated by plant compensatory responses. Conclusions Individuals of Erysimum capitatum are visited by diverse groups of pollinators and herbivores that shift in abundance and importance in time and space. Compensatory reproductive mechanisms mediate interactions with both pollinators and herbivores and may allow E. capitatum to succeed in this complex selective environment. [ABSTRACT FROM PUBLISHER]

Background and Aims: Variability in embryo development can influence the rate of seed maturation and seed size, which may have an impact on offspring fitness. While it is expected that embryo development will be under maternal control, more controversial hypotheses suggest that the pollen donor and the embryo itself may influence development. These latter possibilities are, however, poorly studied. Characteristics of 10-d-old embryos and seeds of wild radish (Raphanus sativus) were examined to address: (a) the effects of maternal plant and pollen donor on development; (b) the effects of earlier reproductive events (pollen tube growth and fertilization) on embryos and seeds, and the influence of embryo size on mature seed mass; (c) the effect of water stress on embryos and seeds; (d) the effect of stress on correlations of embryo and seed characteristics with earlier and later reproductive events and stages; and (e) changes in maternal and paternal effects on embryo and seed characteristics during development. [ABSTRACT FROM PUBLISHER]

Aim: To investigate the nisin Z innocuity using normal human gingival fibroblast and epithelial cell cultures, and its synergistic effect with these gingival cells against Candida albicans adhesion and transition from blastospore to hyphal form. Methods and Results: Cells were cultured to 80% confluence and infected with C. albicans in the absence or presence of various concentrations of nisin Z. Our results indicate that only high concentrations of nisin Z promoted gingival cell detachment and differentiation. Determination of the LD50 showed that the fibroblasts were able to tolerate up to 80 μg ml−1 for 24 h, dropping thereafter to 62 μg ml−1 after 72 h of contact, compared to 160 μg ml−1 after 24 h, and 80 μg ml−1 after 72 h recorded by the gingival epithelial cells which displayed a greater resistance to nisin Z. The use of nisin Z even at low concentration (25 μg ml−1) at appropriate concentrations with gingival cells significantly reduced C. albicans adhesion to gingival monolayer cultures and inhibited the yeast’s transition. Conclusion: These findings show that when used at non-toxic levels for human cells, nisin Z can be effective against C. albicans adhesion and transition and may synergistically interact with gingival cells for an efficient resistance against C. albicans. Significance and Impact of the Study: This study suggests the potential usefulness of nisin Z as an antifungal agent, when used in an appropriate range. [ABSTRACT FROM AUTHOR]

Aims: To investigate the efficacy of nisin Z, an antimicrobial peptide produced by certain strains of Lactococcus lactis against Candida albicans growth and transition. Methods and Results: Candida albicans was cultured in the presence of various concentrations of nisin Z (1000, 500, and 100 μg ml−1) for different time points. Candida albicans growth was determined using the Alamar Blue assay. The yeast’s transition from blastospore to hyphal form was assessed through optical microscope observations. The effect of nisin Z on C. albicans ultrastructure was followed by scanning and transmission electron microscopy. Our results show that nisin Z inhibited C. albicans growth beginning at 500 μg ml−1. This inhibition was both time- and dose-dependent. Nisin Z was also active against C. albicans transition by significantly inhibiting the transformation of C. albicans from the blastospore to hyphal form. Treatments with nisin Z lead to ultrastructural disturbances of C. albicans. Conclusion: Our findings indicate that nisin Z significantly reduced C. albicans growth and transition. These effects may have occurred through ultrastructural modifications of this yeast. Significance and Impact of the Study: For the first time, effect of nisin Z on C. albicans was investigated. These results therefore suggest that nisin Z may have antifungal properties, and could be used as an antifungal molecule. [ABSTRACT FROM AUTHOR]