Rapid flow cytometry - Nile red assessment of PHA cellular content and heterogeneity in cultures of Pseudomonas aeruginosa 47T2 (NCIB 40044) grown inwaste frying oil

The accumulation of cytoplasmic polyhydroxyalkanoates (PHAs) and the hetero geneity of bacterial populations were analysed by flow cytometry and SYTO-1 3 and Nile red staining in rhamnolipid-producing Pseudomonas aeruginosa cul tures grown in waste frying oil as carbon source. A combination of SYTO-13 and Nile red fluorescence with cytometric forward and side scatter values m ay allow increases in the final production of polyhydroxyalkanoates (PHA) b y two basic mechanisms: (i) rapid assessment of polyhydroxyalkanoate conten t and (ii) definition of flow cytometric cell sorting protocols to select h igh polyhydroxyalkanoate (PHA)-producing strains. We report a rapid (less t han 30 min) flow cytometric assessment of PHAs in Pseudomonas aeruginosa 47 T2 following Nile red staining: (i) to estimate cellular PHAs content; (ii) to study heterogeneity of the batch cultures producing PHAs and (iii) to e stablish the basis for sorting sub-populations with a high capacity to accu mulate PHAs.