Cryopreservation of Bacterial Vegetative Cells Used in Antibiotic Assay

Abstract

A long-term cryopreservation study of vegetative cells of Micrococcus lutea ATCC 9341a, Micrococcus lutea ATCC 15957, and Staphylococcus epidermidis ATCC 12228 cells, used in our antibiotic bioassay procedure, was conducted. The cryoprotective abilities of 1% methylcellulose solution and a 15% glycerol solution at −14°C were determined. More organisms remained viable in 1% methylcellulose than in 15% glycerol. Overall survival of Staphylococcus epidermidis ATCC 12228 after 365 days was 1.5 logs lower than the other 2 organisms. The sensitivity and the resistance of the preserved organisms to various antibiotics did not change: The methodology is simple and inexpensive, saves analytical time, and avoids risk of contamination and sudden loss of a well-characterized culture.

Adhesion of a Monolayer of Fibroblast Cells to Fibronectin under Sonic Vibrations in a Bioreactor

“…These phenomena were easily observed by use of phase contrast inverted microscopy (images not shown). The results coincided with findings from other laboratories, in which cells responded positively to solutions containing up to 2% MC [19][20][21][22] and MC prevented human skin fibroblast cells from losing their adhesive properties. 23 Having balanced the trade-offs between viscosity, gap size, and cell viability, we could meet the stress linearity criterion to the extent that less than a quarter-wavelength existed between the plates.…”