Xylanase production by Thermobacillus xylanilyticus is impaired by population diversification but can be mitigated based on the management of cheating behavior

Microbial Cell Factories

Frédéric Vélard¹  Harivony Rakotoarivonina²  Romain Bouchat²  Caroline Rémond²  Frank Delvigne³  Damien Rioult⁴  Sandra Audonnet⁵ 

[1] BIOS EA 4691 “Biomatériaux et Inflammation en site osseux”, Université de Reims Champagne Ardenne;INRAE, FARE, UMR A 614, Chaire AFERE, Université de Reims Champagne Ardenne;Laboratory of Microbial Processes and Interactions, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liege;Plateau Technique Mobile de Cytométrie Environnementale MOBICYTE, Université de Reims Champagne-Ardenne;URCACyt, Flow Cytometry Technical Platform, Université de Reims Champagne-Ardenne;

关键词: Hemicellulases;    Xylanases;    Thermobacillus xylanilyticus;    Successive cultivation;    Population diversification;    Cell sorting;   

DOI  :  10.1186/s12934-022-01762-z

来源: DOAJ

【 摘 要 】

Abstract Background The microbial production of hemicellulasic cocktails is still a challenge for the biorefineries sector and agro-waste valorization. In this work, the production of hemicellulolytic enzymes by Thermobacillus xylanilyticus has been considered. This microorganism is of interest since it is able to produce an original set of thermostable hemicellulolytic enzymes, notably a xylanase GH11, Tx-xyn11. However, cell-to-cell heterogeneity impairs the production capability of the whole microbial population. Results Sequential cultivations of the strain on xylan as a carbon source has been considered in order to highlight and better understand this cell-to-cell heterogeneity. Successive cultivations pointed out a fast decrease of xylanase activity (loss of ~ 75%) and Tx-xyn11 gene expression after 23.5 generations. During serial cultivations on xylan, flow cytometry analyses pointed out that two subpopulations, differing at their light-scattering properties, were present. An increase of the recurrence of the subpopulation exhibiting low forward scatter (FSC) signal was correlated with a progressive loss of xylanase activity over several generations. Cell sorting and direct observation of the sorted subpopulations revealed that the low-FSC subpopulation was not sporulating, whereas the high-FSC subpopulation contained cells at the onset of the sporulation stage. The subpopulation differences (growth and xylanase activity) were assessed during independent growth. The low-FSC subpopulation exhibited a lag phase of 10 h of cultivation (and xylanase activities from 0.15 ± 0.21 to 3.89 ± 0.14 IU/mL along the cultivation) and the high-FSC subpopulation exhibited a lag phase of 5 h (and xylanase activities from 0.52 ± 0.00 to 4.43 ± 0.61 over subcultivations). Serial cultivations on glucose, followed by a switch to xylan led to a ~ 1.5-fold to ~ 15-fold improvement of xylanase activity, suggesting that alternating cultivation conditions could lead to an efficient population management strategy for the production of xylanase. Conclusions Taken altogether, the data from this study point out that a cheating behavior is responsible for the progressive reduction in xylanase activity during serial cultivations of T. xylanilyticus. Alternating cultivation conditions between glucose and xylan could be used as an efficient strategy for promoting population stability and higher enzymatic productivity from this bacterium.

【 授权许可】

Unknown