Isolation of Bacteria and Fungi from Human Pancreatic Tumors and Duodenum.

Pancreatic ductal adenocarcinoma has a unique tumor microbiome, and the depletion of gut bacteria or fungi using antibiotic/antifungal cocktails has been shown to decrease pancreatic tumor burden in mice. However, functional studies evaluating the role of tumor-associated microbes are few due to the limited availability of clinically relevant microbiota. Here, we describe in detail an effective workflow for the isolation of bacteria and fungi from the duodenum and tumor of pancreatic cancer patients, specifically optimized for cryopreserved, low biomass samples. Using this workflow we also isolated microbiota from normal pancreatic tissue and duodenum from organ donors, and we confirmed the presence of bacteria and fungi isolated from tissue samples with 16S and ITS sequencing analysis. Isolation and sequencing results show distinct similarities between the pancreatic and duodenal microbiomes and highlight unique bacterial strains that survive in the tumor microenvironment. As a proof of concept, we characterized a select Klebsiella oxytoca strain (UMKO1) isolated from a pancreatic tumor, using whole genome sequencing, metabolomics, and ex- vivo tumor cultures to determine its potential impact on the pancreatic tumor microenvironment. In summary, this optimized workflow allows for the isolation of a variety of bacteria and fungi from low biomass, cryopreserved pancreatic and duodenal tissues, which can then be used for functional studies characterizing clinically relevant tumor-associated microbiota.