Paraformaldehyde in the plant biotechnology laboratory: disinfestation of heat-sensitive utensils

Abstract

Aiming at adapting an easily executed, low-cost technique for the disinfestation of hcat-sensitive utensils, research was developed using plastic Petri pintes (diameter=6cm) submitted to different times of cxposure to paraformaldehyde tablets. During the disinfestation period, thc material remained at 25±2°C and RI-1-50%. Two experimento v,•erc carricd out, with limes of exposurc varying from zero (control) to 32 hours. After disinfestation, 5m1 of lhe cultura medium MS-1962 wcrc poured onto cach plate in a sterile cnvironment. The material was kept in the dark at 25±2 °C, and evalualed weekly unti I the 28th day, as to perecntage of contamination, numbcr ofcolonies per plate and size of the colonics. In the control treatment, 100% ofcontamination was observed. The regression equation of both experimento aliou , the conelusion that. under the conditions tested, the minimum time for satisfactory disinfestation (0% of contamination) is 10h of exposurc to 0.2% paraformaldehyde and 5:30h to 0.4% (m/ v). The treatments allowcd reuse of discardable material, saving rcsourccs and reducing volumes of %vasta.