Redução de esporos de Bacillus subtilis e Bacillus thuringiensis após tratamento com ortoftalaldeído por fumigação a seco ou solução de amônia e glutaraldeído por spray

Abstract

Bacillus spores are used as indicators to assess the quality of disinfection and sterilization. Formaldehyde is a highly efficient disinfectant, but it has several disadvantages during its use, such as a strong odor and carcinogenic property. Orthophthalaldehyde (ORT) and ammonia and glutaraldehyde (AG) solution are alternatives to formaldehyde. The work in question sought to evaluate the reduction of spores of Bacillus subtilis (BS) and Bacillus thuringiensis (BT) after treatment with ORT by dry fumigation and AG solution by spray. In the test performed initially, BT and BS spores were treated with 500uL/m3 of ORT (which is equivalent to 22.5mg of active product/m3 ) or AG by aspersion (500ug per gauze) for 20 minutes. In the second test, BS and BT spores were treated with (2.5mL/m3 of ORT (which equals 112.5mg/m3 of the active product) for 40 minutes. Spores treated with ORT (1.405 mg/mL) for 20 minutes by dry fumigation showed 82.01% and 99.09% inhibition in BS and BT spores, respectively. When we treated BS and BT spores for 40 minutes at (~2.5mL/m3 ) with ORT the reduction was 93. 5% and 100%, respectively. After carrying out the tests, the minimum bactericidal concentration (MBC) of ORT and AG in spores of BT and BS was performed by the microdilution method in plates. The MBC of AG was 15.62mg/mL and 7.81mg/mL in BS and BT spores, respectively. ORT CBM was 11.25mg/mL and 5.62mg/mL in BS and BT spores, respectively. Although the MIC result of AG was similar compared to ORT, ORT was more efficient in inhibiting spores when we simulated the conditions indicated for use in the field. For BT, ORT (~2.5mL/ for 40 minutes which is equivalent to 112.5mg/m3 of the active product) showed a sporicidal effect showing the high disinfection efficiency of this disinfectant. ORT can be used in disinfection processes in laboratories or aviculture, replacing the already known disinfectants. However, studies must be carried out by increasing the ORT time or AG dose to evaluate the sporicidal effect on BS.