Fermentação de lactobacilos para aplicação no tratamento de biofilmes de Candida albicans

• Ano de defesa: 2025
• Autor(a) principal: Tissiani, Ana Caroline
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade de Passo Fundo; Brasil; UPF; Programa de Pós-Graduação em Envelhecimento Humano; Instituto da Saúde
• Palavras-chave em Português: Envelhecimento; Biofilme; Candida albicans; Lactobacilo; Probióticos; Soro de leite; Ciências da Saúde
• Link de acesso: https://repositorio.upf.br/handle/123456789/9638

Human aging is associated with physiological changes, including shifts in the microbiota and increased susceptibility to infections, such as those caused by Candida albicans. This opportunistic microorganism forms biofilms that are highly resistant to antifungals, especially in the elderly. C. albicans' resistance to conventional treatments drives the search for more effective therapeutic alternatives. Probiotics are microorganisms that, when administered in adequate quantities, offer health benefits to the host, such as immune modulation, pathogen inhibition, and infection prevention. Among probiotics, lactic acidproducing bacteria, such as Lactobacillus lactis, L. fermentum, and L. reuteri, stand out for their ability to synthesize bacteriocins, such as nisin, which has antimicrobial and antibiofilm properties. In article 1, a systematic review was conducted, including research on articles in the Web of Science, PubMed, and Scopus databases between 2012 and 2023. The objective was to review the different cultivation conditions for lactic acid bacteria to optimize the production of the bacteriocin nisin, as well as chromatographic purification methods. The results indicated that MRS medium, at temperatures of 30–37°C for 24–48 hours, is the most commonly used for cultivating lactic acid bacteria, with nisin production enhanced by supplements such as powdered milk, peptone, and NaCl. Bacteriocin purification involves centrifugation and analysis by liquid chromatography. Although these conditions are effective, there is a lack of studies exploring more varied and sustainable parameters, in addition to the difficulty in establishing chromatographic standards due to the diversity of bacteriocins produced by different lactobacilli. Chapter 2 aimed to optimize the culture conditions for the probiotics L. fermentum, L. lactic acid, and L. reuteri in whey and to evaluate their antifungal and antibiofilm potential against C. albicans under different conditions. The research was conducted in vitro using activated lactobacillus cultures in conventional MRS broth and subsequently grown in whey with different concentrations of sucrose (0.5%, 1.5%, and 2.5% w/v), NaCl (1%, 2.5%, and 4% w/v), and pH variations (5%, 6%, and 7%). A complete factorial experimental design evaluated the impact of these variables on microbial growth and the production of antimicrobial compounds. The results showed that all strains displayed antifungal activity against C. albicans, with similar inhibition zones and no statistically significant differences. Antibiofilm activity was most significant for L. fermentum and L. lactis, while L. reuteri showed low efficacy. Strain growth was favored by acidic pH conditions, high NaCl concentrations, and sucrose, especially for L. reuteri and L. lactis. Increased sucrose and decreased NaCl significantly influenced the growth of L. fermentum, while pH was decisive for L. lactis. For L. reuteri, increased NaCl also favored biomass production. Furthermore, whey reduced the pH throughout fermentation, favoring the 14 production of antimicrobial metabolites. Whey has proven to be a sustainable and economically viable alternative for the cultivation of probiotics with antifungal and antibiofilm activity. For the first time, the potential of L. fermentum and L. lactis grown in whey to inhibit C. albicans biofilms has been demonstrated, indicating a promising path for the development of new, natural, low-cost therapies against fungal infections. The study reinforces the biotechnological value of reusing industrial waste such as whey, contributing to sustainability and innovation in healthcare.