Global analyses imply that Stenotrophomonas maltophilia biofilms are phenotypically highly diverse despite a common transcriptome profile

Stenotrophomonas maltophilia is one of the most frequently isolated multidrug resistant opportunistic pathogens. It contributes to disease progression in cystic fibrosis patients and is found in wounds, other infected tissues and on catheter surfaces. Only little is known on key processes linked to biofilm formation of S. maltophilia on a broader basis. Thus the aim of this study was the identification of key processes involved in biofilm formation of S. maltophilia on a global level. Therefore, we analyzed biofilm profiles of 300 globally collected clinical and environmental isolates of the main and recently identified lineages Sgn3, Sgn4 and Sm2 - Sm18 (Groeschel et al., 2020). These data together with the 3D structural analysis of a subset of clinical 40 clinical isolates revealed an unexpectedly high phenotypic variability on a strain specific level. Further transcriptome analysis of seven clinical isolates using biofilm grown cells identified a set of 106 shared and coexpressed genes and roughly 30-35 strain-specific genes. Based on these findings S. maltophilia employs a mostly fermentative growth modus under the biofilm conditions and uptake of iron, phosphorous and other metals appears to be of high relevance. Surprisingly, the transcriptome profiles of biofilm versus planktonic cells revealed that only 8.6% of all genes were differentially regulated when both conditions were compared.  This implies that only relatively few genes contribute to the change from planktonic to biofilm life style. Thereby iron uptake appears to be a key factor involved in this metabolic shift. The transcriptome data generated in this study together with the phenotypic and metabolic analysis represent so far the largest data set on S. maltophilia biofilm versus planktonic grown cells. This study now lays the foundation for the identification of new strategies in fighting S. maltophilia infections in clinical settings.

Ref:  Gröschel et al., 2020 ,The phylogenetic landscape and nosocomial spread of the multidrug-resistant opportunist Stenotrophomonas maltophilia. Nature Commun. 2020 Apr 27;11(1):2044. doi: 10.1038/s41467-020-15123-0.