Knowledge about the correlations between the composition of the gut microbiome and a wide range of diseases has substantially increased in recent years. Nonetheless, there is no reference set of information about the microbiome in Poland. The development of such a reference will allow polish scientists conducting research in the field of interaction between gut flora components and such characteristics as lifestyle, certain diseases or patient's responses for treatment. Following the example of such countries as the United States, investigators propose to build a unique set of scientific processed information describing the variability of the polish population microbiome (Polish Microbiome Map). The investigators will provide a reliable dataset that will characterize the gut microbiomes and their diversity in the polish population. Additionally, thanks to the creation of the standard protocol for microbiome data collection the research conducted by the MMP users will be comparable with the information deposited in MMP.

Inclusion Criteria for Healthy Volunteers group:

• Men or women ≥18 years of age
• Patients with informed consent to participate in the study.

Inclusion Criteria for Melanoma group:

• Men or women ≥18 years of age
• Patients with melanoma
• Patients with informed consent to participate in the study.
• Patients receiving routine treatment (immunotherapy using anti-PD1 / anti-PDL1 and / or anti CTLA4 antibodies), financed by the Polish National Health Fund (NFZ).
• The applied immunotherapy should be the first or second line of treatment.

Exclusion Criteria:

• Patients or Healthy Volunteers who are unable to understand, read and / or sign the informed consent
• Patients or Healthy Volunteers who can not collect stools
• Patients with a fecal transplant
• The applied immunotherapy is not the first or second line of treatment.

Healthy volunteers or oncology patients with primary care clinic