Abstract
The objective of this study was to evaluate the efficacy of cleaning and decontamination procedures in liquid nitrogen tanks. We evaluated 151 canisters and 133 bottoms from 133 nitrogen tanks of companies or farms for the presence of bacteria and fungi. Samples were collected from the canisters and the bottom of tanks containing liquid nitrogen. Tanks were divided into Group 1 (G1): tanks decontaminated with 2% glutaraldehyde - Glutaron® II (n = 16 canisters in 8 tanks); Group 2 (G2): decontamination with 70% ethanol (n = 20 canisters in 10 tanks); and Group 3 (G3): decontamination with 70% ethanol (n = 115 canisters in 115 tanks). Tanks in Groups 1 and 2 belonged to companies; Group 3 tanks belonged to farms. The culture of canisters showed twelve genera of bacteria and five genera of fungi. Bacillus cereuswas the most prevalent bacterial contaminant (42/133) in liquid nitrogen tanks (31.57%). Decontamination by 2% glutaraldehyde plus 70% ethanol was effective and no difference was found between the decontamination methods of Groups 1 and 2. In Group 3 the decontamination method was considered effective. Handling procedures with high hygienic standards should be recommended to avoid contamination of liquid nitrogen tanks on farms.
Highlights
Liquid nitrogen usually exhibits a very low microbial count during production, but during its storage and distribution it may become an effective media for the cryopreservation of fungal spores, yeasts, bacteria, and viruses (Grout and Morris, 2009)
We evaluated 151 canisters and 133 bottoms from 133 nitrogen tanks of companies or farms for the presence of bacteria and fungi
Tanks were divided into Group 1 (G1): tanks decontaminated with 2% glutaraldehyde - Glutaron® II (n = 16 canisters in 8 tanks); Group 2 (G2): decontamination with 70% ethanol (n = 20 canisters in 10 tanks); and Group 3 (G3): decontamination with 70% ethanol (n = 115 canisters in 115 tanks)
Summary
Liquid nitrogen usually exhibits a very low microbial count during production, but during its storage and distribution it may become an effective media for the cryopreservation of fungal spores, yeasts, bacteria, and viruses (Grout and Morris, 2009). It is known that contamination can occur during tissue, semen or embryo storage in liquid nitrogen and the cryopreservation of external microorganisms can occur by extravasation of cryoprotectors used in semen from damaged straws (Piaseka-Serafin, 1972; Bielansky et al, 2003; Bielanski, 2005a; Morris, 2005). The efficacy of cleaning and decontamination procedures was evaluated by collecting samples before and after decontamination of the tanks These samples were used to identify bacteria and fungi contaminants
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