Biofilm-producing ability and efficiency of sanitizing agents against Prototheca zopfii isolates from bovine subclinical mastitis

Autor(es)

Goncalves, Juliano Leonel ^[1] ; Lee, Sarah Hwa In ^[2] ; Arruda, Eurico de Paula ^[3] ; Galles, Debora Pedroso ^[2] ; Caetano, Vincius Camargo ^[3] ; Fernandes de Oliveira, Carlos Augusto ^[2] ; Fernandes, Andrezza Maria ^[3] ; dos Santos, Marcos Veiga ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Anim Sci, BR-13635900 Pirassununga, SP - Brazil

^[2] Univ Sao Paulo, Sch Anim Sci & Food Engn, Dept Food Engn, BR-13635900 Pirassununga, SP - Brazil

^[3] Univ Sao Paulo, Sch Anim Sci & Food Engn, Dept Vet Med, BR-13635900 Pirassununga, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF DAIRY SCIENCE; v. 98, n. 6, p. 3613-3621, JUN 2015.
• Citações Web of Science: 9

Resumo

The objectives of the present study were to evaluate (1) the capacity of the microalga Prototheca zopfii isolated from subclinical bovine mastitis cases to form biofilms; and (2) the resistance of these isolates to sanitizing agents. Ten isolates of P. zopfii from cows with subclinical mastitis (somatic cell count >200 x 103 cells/mL), distributed in 5 dairy farms, were evaluated for their capacity to form biofilms in polystyrene microplate assays and stainless steel coupons, at 25 degrees C and 37 degrees C +/- 1 degrees C. Prototheca zopfii were isolated from milk samples via microbiological culture and analyzed by 18S rRNA gene sequencing. Biofilm formation on the coupons was observed by scanning electron microscopy. The resistance to sanitizing agents was assessed using the biofilm-forming P. zopfii isolates in stainless steel coupon assays, which were subjected to 3 sanitizers: peracetic acid, sodium hypochlorite, and iodine solution. To evaluate resistance to the sanitizers, the minimum inhibitory concentration (MIC) technique was performed using decreasing concentrations of the sanitizing agents (20, 10, 5, 2.5, 1.25, 0.625, 0.312, 0.156, 0.078, 0.039, and 0.019 g/L). After inoculating the isolates, all concentrations were evaluated at 3 distinct incubation periods (24, 48, and 72 h) to assess the effect of incubation time on the MIC. Using the polystyrene microplate assays, 1 isolate showed weak biofilm production, 5 moderate, and 4 strong, when incubated at 25 degrees C +/- 1. For isolates incubated at 37 degrees C +/- 1, 6 showed weak biofilm production and 4 moderate. All P. zopfii isolates (n = 10) had the capacity to form biofilms on stainless steel coupons. The longer the incubation period of the P. zopfii isolates at different dilutions, the greater the concentrations of sanitizer needed to prevent growth of the microalgae under the tested conditions. We detected a significant effect of sanitizer and time of incubation (24, 48, and 72 h) on MIC values against P. zopfii isolates. The isolates were sensitive in vitro to peracetic acid (MIC90 >= 0.019 g/L), sodium hypochlorite (MIC90 >= 0.312 g/L), and iodine solution (MIC90 >= 0.625 g/L), after 24 h of incubation (where MIC90 = concentration needed to inhibit 90% of isolates). Of the tested sanitizers, peracetic acid had the greatest efficiency against P. zopfii. We conclude that P. zopfii isolates are capable of biofilm production, which may contribute to their persistence in a milking and dairy environment. (AU)

• Processo FAPESP: 13/23613-8 - Impacto da mastite subclínica sobre custo de produção e qualidade do leite em rebanhos leiteiros
• Beneficiário: Juliano Leonel Gonçalves
• Modalidade de apoio: Bolsas no Brasil - Doutorado