Glycogen, the preferred energy source for extracellular protein formation and growth of Aeromonas salmonicida

A study was made of the effect of supplementing a rich 3% (w/v) tryptone soya broth (TSB) medium and a poorer 1.7% (w/v) tryptone-based medium with glucose, maltose and glycogen, as carbon sources, on growth and exoprotein formation by Aeromonas salmonicida. In TSB, glucose inhibited growth and repressed exoprotein formation whilst maltose and glycogen had little effect, up to 20 h, when compared with an unsupplemented control. By contrast, in the poorer medium, over a 24-h incubation period, growth was stimulated three-fold by glycogen, and whilst exoprotein formation was low in comparison with that observed in TSB, the greatest production was observed in the presence of glycogen. Extracellular alpha-amylase was measured in the tryptone medium in the presence of the three carbon sources and the highest level, produced in the presence of glycogen, was 1.6 times that with added maltose whilst none was detectable with glucose present. This pattern was repeated in the case of the maltose-inducible porin, LamB, of the outer membrane.

Toward bacterial protein sub-cellular location prediction:single-class discrimminant models for all gram- and gram+ compartments

Based on Bayesian Networks, methods were created that address protein sequence-based bacterial subcellular location prediction. Distinct predictive algorithms for the eight bacterial subcellular locations were created. Several variant methods were explored. These variations included differences in the number of residues considered within the query sequence - which ranged from the N-terminal 10 residues to the whole sequence - and residue representation - which took the form of amino acid composition, percentage amino acid composition, or normalised amino acid composition. The accuracies of the best performing networks were then compared to PSORTB. All individual location methods outperform PSORTB except for the Gram+ cytoplasmic protein predictor, for which accuracies were essentially equal, and for outer membrane protein prediction, where PSORTB outperforms the binary predictor. The method described here is an important new approach to method development for subcellular location prediction. It is also a new, potentially valuable tool for candidate subunit vaccine selection.