MYCOBACTERIA PRODUCE PROTEINS INVOLVED IN BIOFILM FORMATION AND GROWTH-AFFECTING PROCESSES JOANA KORABLIOVIENĖ 1,2 *, MYKOLAS MAURICAS 1 , ČESLOVA AMBROZEVIČIENĖ 3 , MINDAUGAS VALIUS 4 ,ALGIRDAS KAUPINIS 4 , SAULIUS ČAPLINSKAS 5,6 and PAVEL KORABLIOV 1 1 Department of Immunology, State Research Institute, Centre for Innovative Medicine, Vilnius, Lithuania 2 Department of Epidemiological Surveillance, Centre for Communicable Diseases and AIDS, Vilnius, Lithuania 3 Department of Bacteriology, National Food and Veterinary Risk Assessment Institute, Vilnius, Lithuania 4 Vilnius University Life Sciences Center, Institute of Biochemistry, Proteomics Center, Vilnius, Lithuania 5 Faculty of Social Policy, Mykolo Romerio University, Vilnius, Lithuania 6 Centre for Communicable Diseases and AIDS, Vilnius, Lithuania (Received: 17 July 2017; accepted: 31 May 2018) The aim of this study was to determine the effect of mycobacterial proteins on mycobacterial biofilm formation and growth processes. We separated growth- affecting proteins (GEPs) from wild type of Mycobacterium bovis and ATCC strain of Mycobacterium avium subsp. avium. Our results showed that these mycobacteria- secreted GEPs are involved in biofilm formation, growth stimulatory, and inhibitory processes. Our findings suggest that GEP stimulated M. avium subsp. avium growth in vitro. Stimulation process was observed in mycobacteria affected with GEP extracted from M. avium subsp. avium. We found that both GEPs inhibited the growth of the M. bovis. Optical density measurement and visual analysis confirm that GEP plays an important role in biofilm formation process. Most of M. bovis GEP are associated with the type VII secretion and general secretion pathways. Our results contribute to a better understanding of the mechanisms underlying mycobacterial biofilm formation and growth-affecting processes and better characterization of mycobacterial proteins and their functions. It is noteworthy that this finding represents the first demonstration of GEP-mediated growth effects on a solid and liquid medium. Keywords: mycobacterial proteins, mycobacterial biofilms, mycobacterial growth processes *Corresponding author; E-mail: tamkeviciute.joana@gmail.com Acta Microbiologica et Immunologica Hungarica 65 (3), pp. 405–418 (2018) DOI: 10.1556/030.65.2018.033 First published online July 18, 2018 1217-8950/$20.00 © 2018 Akadémiai Kiad´ o, Budapest