Biofilms chemistry within

Microorganisms and Effects on Solution Chemistry within Regions of the Biofilm (Ref72, 73)... 

Biofilms are capable of maintaining environments at biofihn/surface interfaces that are radically different from the bulk fluid in terms of pH, dissolved oxygen, and other organic and inorganic species (Fig. 3). In some cases, these interfacial conditions could not be maintained in the bulk medium at room temperature near atmospheric pressure. The consequence is that microorganisms within biofilms facilitate reactions that are not predicted by thermodynamic arguments based on the chemistry of the bulk medium. 

---