Author, as appears in the article.: Terrones-Fernandez I; Casino P; López A; Peiró S; Ríos S; Nardi-Ricart A; García-Montoya E; Asensio D; Marqués AM; Castilla R; Gamez-Montero PJ; Piqué N

Department: Bioquímica i Biotecnologia

URV's Author/s: Rios Azuara, Santiago

Keywords: Vrbg Tsa Survival Separation of components Selectivity Sda Recovery Pour plate method Pour plate Agar vrbg tsa separation of components selectivity sda recovery pour plate count agar

Abstract: Although the pour plate method is widely employed in microbiological quality control, it has certain drawbacks, including having to melt the culture medium before seeding. In this study, the preparation of the culture medium was modified by using a lower concentration of agar (10 g/L), which was separated from the nutrients during sterilization. The new protocol was assessed in media frequently used in microbiological quality control of food, cosmetics, and pharmaceutical products, with tryptic soy agar (TSA), Sabouraud 4% dextrose agar (SDA), and violet red bile glucose agar (VRBG). In comparison with the conventionally produced media, the modifications significantly improved the growth of Saccharomyces cerevisiae in SDA, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Typhimurium, and Candida albicans in TSA and Escherichia coli ATCC 8739 and ATCC 25922 and S. Typhimurium in VRBG. The modified VRBG was also more selective for Pseudomonas aeruginosa. Regarding physicochemical properties, a significantly lower pH was observed in TSA and VRBG and lower strength values in TSA. Sterilizing agar separately from the other components of the medium and reducing the agar concentration to 10 g/L can improve microorganism growth and enhance the selectivity of differential media in the pour plate method. These modifications could facilitate the automation of this culture technique. IMPORTANCE In the era of rapid microbiological methods, there is a need to improve long-established culture techniques. Drawbacks of the pour plate method include having to melt each medium separately before seeding. For this technique, we demonstrate that separating the agar from the other components of commonly used media during sterilization and reducing the agar concentration to 10 g/L can enhance microbial growth. The new protocol could have advantages in routine laboratory practice because less agar is required and the same molten agar suspension can be used to prepare different media. Moreover, these modifications could facilitate the automation of the pour plate method.

Thematic Areas: Physiology Microbiology (medical) Microbiology Infectious diseases Immunology and microbiology (miscellaneous) Immunology and microbiology (all) Genetics General medicine General immunology and microbiology Ecology Ciências agrárias i Cell biology

licence for use: https://creativecommons.org/licenses/by/3.0/es/

Author's mail: santiago.rios@urv.cat

Author identifier: 0000-0003-2492-9247

Record's date: 2023-02-23

Papper version: info:eu-repo/semantics/publishedVersion

Link to the original source: https://journals.asm.org/doi/10.1128/spectrum.03161-22

Licence document URL: http://repositori.urv.cat/ca/proteccio-de-dades/

Papper original source: Microbiology Spectrum. 11 (1): e0316122-e0316122

APA: Terrones-Fernandez I; Casino P; López A; Peiró S; Ríos S; Nardi-Ricart A; García-Montoya E; Asensio D; Marqués AM; Castilla R; Gamez-Montero PJ; Piqué (2023). Improvement of the Pour Plate Method by Separate Sterilization of Agar and Other Medium Components and Reduction of the Agar Concentration. Microbiology Spectrum, 11(1), e0316122-e0316122. DOI: 10.1128/spectrum.03161-22

Article's DOI: 10.1128/spectrum.03161-22

Entity: Universitat Rovira i Virgili

Journal publication year: 2023

Publication Type: Journal Publications