Avaliação da adesão bacteriana em polímeros empregados na indústria de alimentos irradiados com cobalto 60 / Evaluation of the bacterial adhesion in polymers employed in the food industry irradiated with cobalt 60

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The adhesion of Pseudomonas fluorescens ATCC 13525 to low density polyethylene after irradiation with 0, 5, 10, 20 and 25 kGy was evaluated by the technique of standard counting in plaques (SCP) and epifluorescense microscopy (MEF). It was found that, regardless of the dose of irradiation and the employed technique the adhesion did not exhibit significant difference (p≥0.05) In the evaluation of the adhesion of Staphylococcus aureus ATCC 6523 and of Pseudomonas fluorescens ATCC 13525 in poly-nylon, PEBD and poly (vinyldene chloride) (PVDC) irradiated with cobalt60 in the doses 0, 50, 100, 200, 300 and 400 kGy significant differences were observed (p<0.05) between the microorganisms, polymers, degrees of irradiation and also in the interaction between the microorganisms and the polymers. The adhesion of S. aureus varied from 1,40 to 14,5 UFC.cm-2 per 104 UFC.mL-1 by the SCP technique and from 14,3 to 55,62 UFC.cm-2 per 104 UFC.mL-1 by the MEF, values superior to those found for P. fluorescens, 0.15 to 7,94 and 4,93 to 24,97 UFC.cm-2 per 104 UFC.mL-1, respectively. The process of adhesion of the S. aureus might be explained by the alterations that occurred in the structure of the polymers due to the irradiation. For P. fluorescens adhesion was associated with the alterations in the structures of the polymers due to the irradiation, which suggest, in this case, that other factors contributed to the adhesion process. In the study of the rugosity of the polymers by atomic force microscopy (AFM), and maximum charge of rupture, it was found that that the irradiation altered the micro topography and the resistance of the polymers. These techniques were better than electronic scanning microscopy to evaluate alterations in the rugosity of the polymers. The results indicated that the increase in the irradiation dose on the polymers resulted in a larger microbial adhesion due to physical alterations in the polymeric structure of the polymers.

ASSUNTO(S)

irradiação polímeros bacterial adhesion polymers cobalto 60 irradiation ciencia de alimentos adesão bacteriana cobalt 60

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