Adaptation of Pseudomonas helmanticensis to sodium dodecyl sulfate in the presence of glycerol

Resistant to sodium dodecyl sulfate (SDS) Pseudomonas helmanticensiscan produce polyhydroxyalkanoates (PHA) - biogenic polyesters that may replace synthetic wrapping materials. The resistance to alkyl sulfatesallows to use P. helmanticensis for the development of non-axenic PHA production processes. The addition of SDS to culture media inhibits the growth of unwanted microorganisms. It allows to omit a vapor sterilization step and reduce the cost of the final polymer. Glycerol is a promising substrate for PHA production. Therefore, it is reasonable to study the adaptation of P. helmanticensis to SDS in the media containing glycerol. It is known that Pseudomonas bacteria have several mechanisms that provide resistance to SDS: the aggregate formation, membrane modification, and the synthesis of the enzymes that cleave alkyl sulfates. The presence of aggregates in P. helmanticensis cultures was studied using epifluorescence microscopy. The cells were stained with Acridine orange before microscopy. Modification of the cell membranes was studied by analyzing the fatty acid composition of biomass by gas chromatography - mass spectrometry. The presence of intracellular sulfatases was assessed by the change in SDS concentration. It has been shown that P. helmanticensis adapts to the presence of SDS in media containing glycerol by activation of all three mechanisms. The highest concentration of SDS at which P. helmanticensis shows a significant biomass growth is 0.5 g/L. This concentration inhibits the growth of many other microorganisms. P. helmanticensisis a promising producer for the synthesis of PHA in non-sterile media containing glycerol and SDS.