All experimental work was performed at the University of Latvia, Institute of Microbiology and Biotechnology, following established institutional biosafety standards. Activities with Escherichia coli competent cells (BL21(DE3) and XL1-blue) and bacteriopages (T4, T7, λ) were strictly segregated to preserve correct containment and avoid cross-contamination. Procedures involving phages were conducted exclusively within Class II (BSL-2) biological safety cabinets, providing a controlled, aseptic environment and additional protection for both personnel and surroundings.
Before being granted independent access to the laboratory, every team member completed formal biosafety instruction and practical onboarding. Key requirements included:
1.
Maintaining professional conduct and aseptic technique at all times;
2.
Documenting all experimental steps in the laboratory record;
3.
Wearing appropriate protective clothing — laboratory coats strongly recommended, gloves mandatory when handling chemicals or biological material, protective eyewear recommended for corrosive reagents;
4.
Changing outdoor to indoor footwear before entry and keeping the working area organized and clean.
In our tests, antifungal activity was evaluated on the yeast strain Saccharomyces cerevisiae CEN.PK113-7D. This strain is haploid (MATa) (Nijkamp et al., 2012), and sporulation in S. cerevisiae requires a diploid a/α genotype; haploid cells do not undergo meiosis and spore formation under standard laboratory conditions (Neiman, 2011). Consistent with this, sporulation-specific programs are inactive in haploid CEN.PK113-7D (e.g., sporulation septin gene expression is absent) (Tai et al., 2007). Therefore, CEN.PK113-7D does not produce spores, and spore-related allergen exposure is not expected during our laboratory work.
All chemical and biological waste was handled in accordance with the University of Latvia’s safety regulations
Biohazardous materials — including culture plates, pipette tips and bacterial suspensions — were autoclaved prior to disposal.
Hazardous reagents such as ethidium bromide were collected separately and disposed of via approved chemical waste streams.
Antibiotics and antimicrobial agents were neutralized and discarded through controlled channels to avoid environmental contamination and the emergence of resistance.
The project aims to create casein–hyaluronic acid biomaterials and examine laboratory-safe phage interactions for wound-care applications. All work remains fully contained and poses no risk to human health or the environment. Casein is sourced from standard commercial suppliers with documented origin and licensing compliance. Use of hazardous chemicals was minimized, monitored and managed through approved disposal pathways. No gain-of-function studies, dual-use research concerns or activities enhancing virulence, host range or persistence were undertaken.
[1] Nijkamp, J.F., van den Broek, M., Datema, E. et al. De novo sequencing, assembly and analysis of the genome of the laboratory strain Saccharomyces cerevisiae CEN.PK113-7D, a model for modern industrial biotechnology. Microb Cell Fact 11, 36 (2012). https://doi.org/10.1186/1475-2859-11-36
[2] Neiman A. M. (2011). Sporulation in the budding yeast Saccharomyces cerevisiae. Genetics, 189(3), 737–765. https://doi.org/10.1534/genetics.111.127126
[3] Tai, S. L., Snoek, I., Luttik, M. A. H., Almering, M. J. H., Walsh, M. C., Pronk, J. T., & Daran, J. M. (2007). Correlation between transcript profiles and fitness of deletion mutants in anaerobic chemostat cultures of Saccharomyces cerevisiae. Microbiology (Reading, England), 153(Pt 3), 877–886. https://doi.org/10.1099/mic.0.2006/002873-0