A novel binary biofilm model for the study of the development of antimicrobial tolerance in Pseudomonas aeruginosa PAO1 and Escherichia coli

The primary aim of this study was to investigate the effect of species interactions on biofilm formation and the investigation of the susceptibility of component species towards BIT in binary biofilms (Ps. aeruginosa PAO1and E. coli ATCC 10000). The Sorbarod biofilm model (Hodgson et al. 1995) was used to establish monospecies and binary species biofilms under conditions of growth rate control by the utilisation of a modified Chemically Defined Medium (MCDM). This MCDM was designed to allow the growth of both species (Ps. aeruginosa PAO1and E. coli ATCC 10000) in the same biofilm, without allowing either to have a growth rate advantage over the other. The results from these experiments suggest that it is possible to use this model to investigate the results of environmental exposure of bacteria to sub-MICs of biocides and develop an understanding of their subsequent tolerance and resistance characteristics. These results indicate that it is possible to establish a binary biofilm in chemically defined media, under growth rate control and to induce tolerance in dual species (binary) biofilms towards BIT. The mechanism of tolerance in binary biofilms towards this biocide was a gradual adaptive process, dependent upon the presence of biocide. This study elucidates a novel technique for the establishment, control and operation of binary biofilms. It has yielded information regarding the use of passage approaches to develop antimicrobials tolerance in both monospecies and binary species biofilms of medically important bacteria

Inhibition of dye-coupling in Patella (mollusca) embryos by microinjection of antiserum against Nephrops (arthropoda) gap junctions

Antiserum raised against Nephrops gap junctions was injected into single cells of the 2-, 4-, 8-, 16-, and 32-cell stage of the Patella vulgata embryos. The pattern of junctional communication by iontophoresis of Lucifer Yellow CH was tested at the 32-cell stage. The results show that the normal pattern of dye-coupling at the 32-cell stage is disrupted in greater than 65% of embryos previously injected with antisera. In contrast, less than 15% of embryos injected with preimmune serum exhibited disrupted patterns of dye-coupling. Up to the late 32-cell stage no effect of the antiserum on the pattern of cleavage was detected. This antiserum may provide a powerful tool to investigate the role of junctional communication in later stages of development of Patella embryos