Biomedical subjects
Publications and source records attributed to E H Boykin.
A compact multichannel unit for electrochemical detection of microorganisms that automatically displays detection time length is described. This unit was successfully tested with various members of the Enterobacteriaceae group.
A compact housing unit for low-power (X6 to X50) cinemicrographic studies of microbial specimens in the vertical plane is described. This unit was used successfully to record the development of a "halo" of cells around subsurface colonies of Escherichia coli.
A simple method for detecting bacteria, based on the time of hydrogen evolution, was developed and tested against various members of the Enterobacteriaceae group. The test system consisted of (i) two electrodes, platinum and a reference electrode, (ii) a buffer amplifier, and (iii) a strip-chart recorder. Hydrogen evolution was measured by an increase in voltage in the negative (cathodic) direction and recorded on a strip-chart recorder. Hydrogen response curves consisted of (i) a lag period, (ii) a period of rapid buildup in potential due to hydrogen, and (iii) a period of decline in potential. A linear relationship was established between inoculum size and the time hydrogen was detected (lag period). Lag times ranged from 1 h for 10(6) cells/ml to 7 h for 10(0) cells/ml. For each 10-fold decrease in inoculum, length of the lag period increased 60 to 70 min. Mean cell concentrations at the time of hydrogen evolution were 10(6)/ml. Based on the linear relationship between inoculum size and lag period, these results indicate the potential application of the hydrogen-sensing method for rapidly detecting coliforms and other gas-producing microorganisms in a variety of clinical, food, and other samples.
Cinemicrographic studies revealed that the development of elongated subsurface colonies of Staphylococcus aureus in soft agar (<0.2% agar) originated with a colony-forming unit of about 10 to 20 cells. It was then observed that small clusters of 3 to 12 cells broke off from the main colony unit and drifted away under the combined influence of gravity and Brownian motion. Once the downward or slightly sideward motion of the small clusters ceased, the clusters would continue to increase in size; at the same time, additional small clusters broke off, and the cycle was repeated until the entire colony was formed. Displacement and velocity measurements were made on the drifting small clusters. When compared with the dimensional growth rate and geometry of the subsurface colony, these showed that a correlation existed between the movement and velocity of the small clusters and the subsequent colony development. A relationship between the role of gravity reported in these results and the development of spherical colonies after rotation on a clinostat is suggested.