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Spontaneous loss of quorum sensing control selects a new high cellulose producing Ancylobacter strain

Year: 2025

Type: article

Abstract: In recent years the number of non- Acetobacteraceae strains shown to produce nanofibrillar cellulose at the levels of the known Acetobacteraceae producers has increased considerably. The Ancylobacter sp. STN1B isolate capable of cellulose production from naphthalene has previously been described. In this study, Ancylobacter sp. STN1A, a spontaneous STN1B mutant able to produce 1.7 to 9.7 times higher levels of cellulose, has been isolated. The STN1A genome showed a 62 kb deletion encompassing a modified rpf quorum sensing signalling system that included a diguanylate cyclase-phosphodiesterase gene. A knock-out mutant of STN1B rpfC sensor kinase gene produced similarly high cellulose levels than STN1A. This confirmed that the overproducing phenotype resulted from the loss of the rpf system, which resulted in three-time higher c -di-GMP levels. The strains were able to grow on several carbon sources and produce cellulose with properties similar to those of K. xylinus processed similarly, as determined using ATR-FTIR, CP/MAS, 13 C NMR, XRD, TGA and SEM, although with higher thermal resistance and water holding capacity. Production was higher under static conditions, rendering 2.5 g/L with glycerol. Interestingly, in this strain cellulose is synthesized from a type-III bcs cluster, which lacks BcsC, BcsD and BcsH sub-units. This first thorough characterization of cellulose produced from a type III cellulose synthesis complex reveals its excellent properties. • The non- Acetobacteraceae Starkeya sp. STN1A produces quality crystalline cellulose. • The rpf quorum sensing system controls cellulose synthase in Starkeya sp. STN1B. • Crystalline cellulose is synthesized by a type III bcs cluster, where bcsD is absent.

Source: International Journal of Biological Macromolecules

DOI: 10.1016/j.ijbiomac.2025.140620