Unraveling the extracellular polysaccharide utilization system of Cellulomonas sp. B6

TOPALIAN JULIANA; ONTAÑON ORNELLA M; VALACCO MARIA PIA; GARRIDO MERCEDES M; CAMPOS ELEONORA

virtual

Simposio; 43rd Symposium on Biomaterials, Fuels and Chemicals; 2021

One of the main features of species from Cellulomonas genus is their ability to secrete (hemi)cellulolytic enzymes. We havestudied the exo-proteome of two Cellulomonas isolates, Cellulomonas sp. B6, and C. fimi B-402 when grown on differentlignocellulosic carbon sources and the genetic distribution of the genes encoding for the secreted proteins. Both isolatespresented mainly xylanase activity, although the highest activity was observed by growth on different substrates: wheat bran(WB) for Cellulomonas sp. B6 (3.5 IUxyn/ml) and waste paper (WP) for C. fimi (1.5 IUxyn/ml). By mass spectrometry analysis ofthe extracellular fractions, we identified 28 and 25 GH (out of 197 and 360 total proteins detected) in Cellulomonas sp. B6 and C.fimi, respectively. In the Cellulomonas sp. B6 WB extracellular extract, 2 GH10 xylanases and a GH62 alpha-Larabinofuranosidase were amongst the most abundant proteins. In C. fimi, a single GH10 xylanase was the most abundantprotein. In both extracts, a high abundance of extracellular proteins from ABC sugar transport systems was observed. MostCAZymes were encoded in distant regions of the genome, with few exceptions. In Cellulomonas sp. B6, we identified a clusterencoding a GH43 and a GH10 and both enzymes were detected in WB-secretome. In C. fimi, a GH10 and a GH62 identified inthe secretome were encoded along with the sequence for a GH43. A common feature observed was the presence of codingsequences for sugar transporters (mainly ABC family) and transcriptional regulators along with genes encoding CAZymes. Insummary, Cellulomonas sp. can secrete xylanases and other glycosyl-hydrolases with different relative abundance when culturedin lignocellulosic substrates. The coding sequences for these proteins are distributed along the genome, mostly surrounded bysequences encoding different transcriptional regulators and transporter systems.