“…Creating a partial anaerobic biofilm as bacterial habitat is important for bacterial nitrogen fixation, which may augment the nitrogen budget in lichens lacking a N-compound-donating cyanobiont. Several lichen-associated bacteria, like Alphaproteobacteria ( Grube et al, 2009 ; Almendras et al, 2018 ), Gammaproteobacteria ( Liba et al, 2006 ), Firmicutes ( Grube et al, 2009 ; Almendras et al, 2018 ) and Actinobacteria ( Almendras et al, 2018 ) contain nifH genes. In the case of N-limiting conditions, bacterial N-fixation, by e.g., Azotobacter , Betaproteobacteria or Alphaproteobacteria, could be of considerable importance for the vitality of lichens ( Leveau and Preston, 2008 ; Grube and Berg, 2009 ; Grube et al, 2009 ; Bates et al, 2011 ; Erlacher et al, 2015 ).…”