Increased Zinc Availability Enhances Initial Aggregation and Biofilm Formation of Streptococcus pneumoniae.

Bacteria growing within biofilms are protected from antibiotics and the immune system. Within these structures, horizontal transfer of genes encoding virulence factors, and promoting antibiotic resistance occurs, making biofilms an extremely important aspect of pneumococcal colonization and persistence. Identifying environmental cues that contribute to the formation of biofilms is critical to understanding pneumococcal colonization and infection. Iron has been shown to be essential for the formation of pneumococcal biofilms; however, the role of other physiologically important metals such as copper, zinc, and manganese has been largely neglected. In this study, we investigated the effect of metals on pneumococcal aggregation and early biofilm formation. Our results show that biofilms increase as zinc concentrations increase. The effect was found to be zinc-specific, as altering copper and manganese concentrations did not affect biofilm formation. Scanning electron microscopy analysis revealed structural differences between biofilms grown in varying concentrations of zinc. Analysis of biofilm formation in a mutant strain lacking the peroxide-generating enzyme pyruvate oxidase, SpxB, revealed that zinc does not protect against pneumococcal H2O2. Further, analysis of a mutant strain lacking the major autolysin, LytA, indicated the role of zinc as a negative regulator of LytA-dependent autolysis, which could affect biofilm formation. Additionally, analysis of cell-cell aggregation via plating and microscopy revealed that high concentrations of zinc contribute to intercellular interaction of pneumococci. The findings from this study demonstrate that metal availability contributes to the ability of pneumococci to form aggregates and subsequently, biofilms.

Yeast Autolysis in Sparkling Wine Aging: Use of Killer and Sensitive Saccharomyces cerevisiae Strains in Co-Culture.

BACKGROUND: Sparkling wines produced by traditional method owe their characteristics to secondary fermentation and maturation that occur during a slow ageing in bottles. Yeast autolysis plays an important role during the sparkling wine aging. Using a combination of killer and sensitive yeasts is possible to accelerate yeast autolysis and reduce maturing time. METHODS: killer and sensitive Saccharomyces cerevisiae strains, separately and in co-cultures, were inoculated in base wine and bottled on pilot-plant scale. Commercial Saccaromyces bayanus strain was also investigated. Protein free amino acid and polysaccharides contents and sensory analysis were determined on the wine samples at 3, 6 and 9 months of aging. Yeast autolysis that occurs during the production of sparkling wines, obtained with co-cultures of killer and sensitive strains, has influenced free amino acids, total protein and polysaccharides content after 3 months aging time: sparkling wines, produced without the use of these yeasts, have reached the same results only after 9 months aging time. RESULTS: These results demonstrate that killer and sensitive yeasts in co-culture can accelerate the onset of autolysis in enological conditions, and has a positive effect on the quality of the aroma and flavor of sparkling wine. CONCLUSION: This paper offers an interesting biotechnological method to reduce production time of sparkling wine with economical benefits for the producers. We revised all patents relating to sparkling wine considering only those of interest for our study.

The natural decomposition of adipocere.

Adipocere is a waxy substance which sometimes forms from the adipose tissue of dead bodies, especially when they are under water. A disinterment in southern Ontario lead to the recovery of extensive adipocere from an interment which occurred in AD 1869. Subsequent laboratory research was designed to explore the conditions under which adipocere will disappear, the goal being to identify strategies for estimating a range of time since death in cases where adipocere is present. Varieties of aerobic or facultatively anaerobic microorganisms from the surface of the adipocere were separated and identified. In culture, the gram positive bacteria were able to degrade the adipocere. We propose that the persistence of adipocere is related to the exclusion of gram positive bacteria from the burial environment. The role of bacteria in adipocere formation and degradation must be understood before we can use the presence of adipocere to extrapolate information about the post-death interval.

Adipocere--problems in estimating the length of time since death.

Establishing the length of time since death is particularly difficult in corpses showing advanced autolysis. One sign of advanced decay is the formation of adipocere. In this state bodies show evidence of a partly wax-like and partly pasty condition. Continued storage ultimately results, among other things, in further decomposition due to the action of micro-organisms from the surrounding area-even if this is chronologically delayed. An exception is provided by the formation of adipocere under air-tight conditions. Initially, autolysis and heterolysis also occur, involving the release of fatty acids. As a result of the subsequent hydrogenation of the fats under the influence of bacterial enzymes, the unsaturated fatty acids are partially converted into saturated fatty acids. As the fatty acids clearly have a bactericidal effect, further bacterial decomposition is stopped at this early adipocere stage. Additional micro-organisms from outside can no longer penetrate when this hermetic seal is in place. In addition, the lack of calcium (e.g. from water or moist earth) can be a reason for the fact that further adipocere development, leading to wax-like hardening of the fat, is arrested. Thus the condition of the body can remain constantly preserved over many years and it no longer allows a reliable estimate to be made of the period of time since death.

Penicillin amidohydrolases in fungal autolysis.

The production of penicillin G and penicillin V amidohydrolases or acylases (E.C.3.5.1.11) was studied during the autolysis of filamentous fungi in a mineral medium, and in the same medium with phenoxyacetic acid as inducer. In all the studied fungi, enzymes showing penicillin G and penicillin V amidohydrolase activities were found. Generally, an increase of these activities during fungal autolysis was observed. The presence of phenoxyacetic acid in the medium did not increase these activities. The activities found in the culture fluids were generally higher than that found in the mycelial extracts. Under these conditions, beta-lactamases (penicillinases) were not found. The fungi Alternaria alternata, Fusarium culmorum, Penicillium oxalicum, and the species Penicillium 222 were chosen to study penicillin G and penicillin V acylases. The enzymes were precipitated with tannic acid from the culture fluid of their autolyzed cultures. Some kinetic constants of these activities were determined.