THE LPS CORE GLYCOSILTRANFERASE wabH IS ESSENTIAL FOR COLD GROWTH IN in Pseudomonas extremaustralis

COLONELLA ANTONELA; TRIBELLI PAULA; ESMERALDA SOLAR VENERO; FLORENCIA BENFORTE; LOPEZ NANCY; LIZARRAGA LEONARDO

San Miguel de Tucumán

Congreso; XII Congreso de Microbiología General; 2017

Asociación Civil de Microbiologia General

Temperature is a key factor for bacterial survival and growth. Although most of microorganism could suffer transient changes of temperature, the psycrophiles and psycrotolerant microorganism have developed different adaptation strategies for growth under low temperatures. In Gram-negative bacteria, the lipopolysaccharide LPS is the major component of the outer membrane. In this work we studied the impact of a mutation in the gene wabH, encoding for a glycosyltranferase of the LPS core,in growth and survival under cold conditions in Pseudomonas extremaustralis, an Antarctic bacterium. Under low temperature, the wabH mutant strain was impaired to grow in solid and liquid cultures andto develop visible colonies and to grow in liquid cultures. Stress resistance assays showed that the oxidative stress resistance and the sensitivity to gentamycin was similar between the wild type and the mutant strain showing that the defect of growth under low temperatures was not due a pleiotropicphenotype. Additionally, we analyzed the envelope permeability in a SDS survival colony count assay. The wabH strain showed lower resistance to SDS in comparison to the wild type strain (40.9±11.8 and 12.2±.0%, respectively) suggesting a more permeable state for the mutant strain. Additionally, Nanomechanical measurements using an atomic force microscopy were performed to determine the biophysical behavior of the of the envelope, at 30oC for the wild type, the mutant and thecomplemented strain and at 8oC for the wild type and the complemented strain. The nanomechanical measurements showed that the mutation of wabH affects cell elasticity since the wabH strain presented a higher Young module value (E). These results suggest a more ?rigid? state in the wabH strain than in the wild type. Additionally, the wild type strain presented differences between temperatures, showing a lower E value at 30oC in comparison with 8oC. Our results showed a key role of core LPS in cold adaptation by affecting cell elasticity.