Table 1.

Representative applications and strategies of microorganism-based oxygen shuttles in the treatment of hypoxic tumors.

Microorganism type	O2 generation mechanism	Mode of cancer therapy	References
Cyanobacteria	Photosynthesis	PDT SDT RT	[6,64,65,67,68,71,79,80,82] [83] [88,89]
Chlorella	Photosynthesis	PTT and Chemotherapy PDT RT CDT	[96] [99] [101,102] [105]
Escherichia coli	Engineered E. coli overexpressed CAT to catalyze endogenous O2 production by H2O2. Magnetic Fe3O4 nanoparticles on the surface of E. coli would catalyse O2 production by H2O2 in situ. E. coli was directly used as the reducing agent to react with the KMnO4 aqueous solution via ultrasonication, and the generated MnOX can react with H2O2 to produce O2.	PDT and PTT RT CDT PDT and Chemotherapy	[110] [111] [116] [120]
Shewanella oneidensis	The MnO2 nanosheets were modified on the MR-1 surface to catalyze the endogenous H2O2.	Immunotherapy	[114]
Spirulina platensis	Photosynthesis	RT and PDT	[117]