TY - JOUR
T1 - Proteinase production in Pseudomonas fluorescens ON2 is affected by carbon sources and allows surface-attached but not planktonic cells to utilize protein for growth in lake water
AU - Nicolaisen, Mette Haubjerg
AU - Worm, Jakob
AU - Jørgensen, Niels O. G.
AU - Middelboe, Mathias
AU - Nybroe, Ole
N1 - © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
PY - 2012
Y1 - 2012
N2 - Proteins may be an important carbon and nitrogen source to bacteria in aquatic habitats, yet knowledge on the actual utilization of this substrate by proteolytic bacteria is scarce. In the present study, Pseudomonas fluorescens ON2 produced an alkaline proteinase (AprX) during growth and there was no evidence for cell density-regulated or starvation-induced proteinase production. Proteinase was produced in the absence of an organic nitrogen source, and citrate had a negative while glucose had a positive effect on the production. Hence P. fluorescens ON2 seems to exploit protein sources by expressing the proteinase during growth unless a preferred carbon source like citrate is present. Lake water model systems were subsequently used to investigate the ability of proteolytic versus non-proteolytic ON2 strains to utilize protein for growth at moderate cell densities. Only cells forming surface-attached micro-colonies were able to utilize this resource, while planktonic cells were not. Our experiments are the first to experimentally support models predicting that production of extra-cellular enzymes in dilute environments may be a waste of resources, whereas it represents a favorable feeding strategy in organic matrices like detritus, micro-colonies or biofilm.
AB - Proteins may be an important carbon and nitrogen source to bacteria in aquatic habitats, yet knowledge on the actual utilization of this substrate by proteolytic bacteria is scarce. In the present study, Pseudomonas fluorescens ON2 produced an alkaline proteinase (AprX) during growth and there was no evidence for cell density-regulated or starvation-induced proteinase production. Proteinase was produced in the absence of an organic nitrogen source, and citrate had a negative while glucose had a positive effect on the production. Hence P. fluorescens ON2 seems to exploit protein sources by expressing the proteinase during growth unless a preferred carbon source like citrate is present. Lake water model systems were subsequently used to investigate the ability of proteolytic versus non-proteolytic ON2 strains to utilize protein for growth at moderate cell densities. Only cells forming surface-attached micro-colonies were able to utilize this resource, while planktonic cells were not. Our experiments are the first to experimentally support models predicting that production of extra-cellular enzymes in dilute environments may be a waste of resources, whereas it represents a favorable feeding strategy in organic matrices like detritus, micro-colonies or biofilm.
U2 - 10.1111/j.1574-6941.2011.01285.x
DO - 10.1111/j.1574-6941.2011.01285.x
M3 - Journal article
C2 - 22224410
VL - 80
SP - 168
EP - 178
JO - F E M S Microbiology Ecology
JF - F E M S Microbiology Ecology
SN - 0168-6496
IS - 1
ER -