21 research outputs found
Yarrowia lipolytica growth under increased air pressure: influence on enzymes production
Improvement of microbial cell cultures oxygenation can be achieved by the
increase of total air pressure, which increases oxygen solubility in the medium. In this
work, a pressurized bioreactor was used for Yarrowia lipolytica batch cultivation under
increased air pressure from 1 to 6 bar. Cell growth was strongly enhanced by the pressure
rise. Fivefold and 3.4-fold increases in the biomass production and in specific growth rate,
respectively, were observed under 6 bar. The increase of oxygen availability caused the
induction of the antioxidant enzyme superoxide dismutase, which indicates that the
defensive mechanisms of the cells against oxidative stress were effective and cells could
cope with increased pressure. The pregrowth of Y. lipolytica under increased pressure
conditions did not affect the lipase production ability of the cells. Moreover, the
extracellular lipase activity increased 96% using a 5-bar air pressure instead of air at 1-
bar pressure during the enzyme production phase. Thus, air pressure increase in bioreactors
is an effective mean of cell mass and enzyme productivity enhancement in bioprocess based
in Y. lipolytica cultures
Regulation of the Na+/K+-ATPase Ena1 Expression by Calcineurin/Crz1 under High pH Stress: A Quantitative Study
[EN] Regulated expression of the Ena1 Na+-ATPase is a crucial event for adaptation to high
salt and/or alkaline pH stress in the budding yeast Saccharomyces cerevisiae. ENA1
expression is under the control of diverse signaling pathways, including that mediated
by the calcium-regulatable protein phosphatase calcineurin and its downstream
transcription factor Crz1. We present here a quantitative study of the expression of
Ena1 in response to alkalinization of the environment and we analyze the contribution
of Crz1 to this response. Experimental data and mathematical models substantiate the
existence of two stress-responsive Crz1-binding sites in the ENA1 promoter and
estimate that the contribution of Crz1 to the early response of the ENA1 promoter is
about 60%. The models suggest the existence of a second input with similar kinetics,
which would be likely mediated by high pH-induced activation of the Snf1 kinase.This work was supported by grants BFU2011-30197-C3-01, BFU2014-54591-C2-1-P and EUI2009-04147 (SysMo2) to JA. (Ministry of Industry and Competitivity, Spain, and Fondo Europeo de Desarrollo Regional [FEDER]). JA is the recipient of an Ajut 2014SGR-4 award (Generalitat de Catalunya). DC was recipient of a predoctoral fellowship from the Spanish Ministry of Education. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Petrezsélyová, S.; López-Malo, M.; Canadell, D.; Roque, A.; Serra-Cardona, A.; Marques Romero, MC.; Vilaprinyó, E.... (2016). Regulation of the Na+/K+-ATPase Ena1 Expression by Calcineurin/Crz1 under High pH Stress: A Quantitative Study. PLoS ONE. 11(6):e0158424-e0158424. https://doi.org/10.1371/journal.pone.0158424Se0158424e015842411
Crystallization and preliminary X-ray analysis of cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens
A novel cytochrome c nitrite reductase (TvNiR) has been isolated from the haloalkalophilic bacterium T. nitratireducens. TvNiR crystals were grown by the hanging-drop vapour-diffusion technique