Identificação De Bactérias Psicrotróficas Proteolíticas Isoladas De Leite Cru Refrigerado E Caracterização Do Seu Potencial Deteriorador

Abstract

RESUMOOs objetivos deste estudo foram identificar bactérias psicrotróficas proteolíticas isoladas de leite cru refrigerado, avaliar o seu poder deteriorador e a sua capacidade de adesão em superfícies de aço inoxidável sob temperaturas de refrigeração. Dentre as bactérias gram-positivas, 23,81% e 33,33% dos isolados pertenciam aos gêneros Bacillus e Paenibacillus respectivamente. No grupo de bactérias gram-negativas fermentadoras de glicose foram identificados os gêneros Cedecea, Enterobacter, Hafnia, Klebsiella, Pantoea, Providencia, Rhanella e Serratia e dentre as bactérias gram-negativas não-fermentadoras, os gêneros Acinetobacter, Aeromonas, Burkholderia, Chryseobacteriun (Flavobacterium), Chryseomonas, Moraxella e Pseudomonas. O gênero Pseudomonas foi predominante entre as bactérias identificadas e representou 33,98% do total de isolados. Dentre as bactérias fermentadoras de glicose 14,6%, 15,3% e 20,8% dos isolados apresentaram predominantemente atividade proteolítica a 6,5 ºC, 21 ºC e 35 ºC, respectivamente, enquanto as bactérias gram-negativas não-fermentadoras apresentaram 25% e 23,6% dos isolados com atividades associadas de proteases, lipases e lecitinases a 6,5 ºC e 21 ºC, respectivamente, o que indicou maior potencial deteriorador. Em espécies de bactérias gram-negativas e gram-positivas, constatou-se a produção de enzimas termorresistentes e adesão à superfície de aço inoxidável a 6,5 ºC. Os resultados deste estudo reforçaram a importância da implementação das boas ABSTRACTThis study aimed to identify proteolytic psychrotrophic bacteria isolated from refrigerated raw milk, to evaluate their spoilage potencial and their capability of adhesion to stainless steel surfaces at cold temperatures. Among gram-positive bacteria, 23.81% and 33.33% of isolates belonged to Bacillus and Paenibacillus genera. In the gram-negative glucose fermentative bacteria group, the genera Cedecea, Enterobacter, Hafnia, Klebsiella, Pantoea, Providencia, Rhanella and Serratia were identified, while the genera Acinetobacter, Aeromonas, Burkholderia, Chryseobacteriun (Flavobacterium), Chryseomonas, Moraxella and Pseudomonas were identified among gram-negative non fermentative microorganisms. The genus Pseudomonas, which was predominant, represented 33.98% of total isolates. Among fermenters of glucose bacteria, 14.6%, 15.3% and 20.8% of isolates showed predominantly proteolytic activity at 6.5, 21 and 35 ºC, respectively, while 25% e 23.6% of isolates belonging the gram-negative non-fermenting microorganisms showed associated activities of proteases, lipases and lecithinases at 6.5 and 21 ºC, respectively, emphasizing their greatest spoilage potential. Gram-positive and gram-negative bacteria produced heat resistant proteolytic enzymes and adhesion to stainless steel surfaces at 6.5 ºC. The results of this study reinforce the importance of the implementation of good manufacturing practices in order to prevent milk spoilage and minimize economic and quality losses.

Caracterização e perfil de resistência de bactérias Gram-positivas em tanques de expansão

“…Ao avaliar bactérias psicrotróficas em leite cru refrigerado e seu poder de adesão em aço inoxidável, Oliveira Pinto et al (2015), encontraram em seus estudos que 23,81% dos isolados pertenciam ao gênero Bacillus e 33,33% Paenibacillus, demonstrou que todos os isolados, produziam proteases, lipases e lecitinases, e verificou adesão na superfície de aço inoxidável. Ressaltou a importância das boas práticas no campo e na indústria para que dessa forma minimize a perda econômica.…”

Proteolytic potential of psychrotrophic microorganisms isolated from fresh cheese

“…Sample preparation was performed according to the procedures described by Frank et al (1992). The counting of proteolytic psychrotrophic and psychrotrophic microorganisms was performed according to Pinto et al (2015) with changes in the incubation conditions. After serial dilutions in peptone-salt solution (0.85% w/v NaCl; 0.1% w/v bacteriological peptone), samples were plated onto Plate Count Agar (PCA) supplemented with 2% w/v skimmed milk powder.…”

Diversidade e controle de biofilme formado pela microbiota do leite cru

“…The dominant genera observed during the days of the three treatments belonged to two classes, Gammaproteobacteria and Bacilli, with the class Gammaproteobacteria being dominant in almost every day, with an approximate average of 85% of the relative abundance (Figure 5A). The contaminating microbiota of refrigerated raw milk includes both Gram-positive and Gram-negative microorganisms, but the latter represents more than 75%, among which a large part belong to the Gammaproteobacteria class (Nörnberg et al 2011;Pinto et al 2015). observed that in the biofilms formed by the microbiota of raw milk at 7 ºC, Gammaproteobacteria and Bacilli represented about 50% each of the microorganisms identified.…”

“…Due to the high microbial diversity in raw milk, biofilms on the surfaces of equipment and pipes in the dairy industries can be formed by more than one species interacting in a microbial community (Latorre et al 2010;. It is known that the Gram-negative bacteria represent more than 75% of the microbiota of refrigerated raw milk (Pinto et al 2015;. However, cells adhered to stainless steel (SS) surfaces in the pre-pasteurization and post-pasteurization ducts of a milk processing plant were identified as 56% Gram-positive, while the other 44% were Gram-negative (Cherif-Antar et al 2016).…”