Project description:Bacterial acyl-homoserine lactones upregulated an uncharacterized gene cluster (bta) in Burkholderia thailandensis E264 to produce an uncharacterized polar antibiotic. The antibiotic is identified as a mixture of four bactobolins. Annotation of the bta cluster allows us to propose a biosynthetic scheme for bactobolin and reveals unusual enzymatic reactions for further study.
Project description:Three new bicyclic depsipeptides, which are related to the previously reported thailandepsins A (1), B (2) and C (3), were discovered from the culture broth of Burkholderia thailandensis E264 when supplemented with amino acid precursors, and were subsequently named as thailandepsins D (4), E (5) and F (6), respectively. Enzyme assays showed that 1-6 are potent histone deacetylase (HDAC) inhibitors, particularly toward HDAC1 which represents class I human HDACs.
Project description:Rhamnolipid production was monitored for a period of 216 h using different substrates in Pseudomonas aeruginosa PAO1 and Burkholderia thailandensis E264 which showed comparable crude yields attained by both after 216 h. The crude yield for P. aeruginosa, however, was significantly higher at the early stages of fermentation (72 or 144 h). Additionally, P. aeruginosa produced rhamnolipid with odd and even carbon chain lipid moieties using odd carbon chain fatty acid substrates (up to 45.97 and 67.57%, respectively). In contrast, B. thailandensis produced rhamnolipid with predominantly even carbon chain lipid moieties (up to 99.26). These results indicate the use of the fatty acid synthesis (FAS II) pathway as the main source of lipid precursors in rhamnolipid biosynthesis by B. thailandensis. Isotope tracing using 0.25% stearic acid - d 35 +?1% glycerol as carbon substrate showed a single pattern of deuterium incorporation: with predominantly less than 15 deuterium atoms incorporated into a single Di-C14-C14 rhamnolipid molecule. This further indicates that the FAS II pathway is the main source of the lipid precursor in rhamnolipid biosynthesis by B. thailandensis. The pathogenicity of these strains was also assessed, and results showed that B. thailandensis is significantly less pathogenic than P. aeruginosa with an LC50 at 24 h >?2500, approximately three logs higher than P. aeruginosa using the Galleria mellonella larva model.
Project description:Natural product gene clusters are often tightly regulated, resulting in gene cluster silencing in laboratory fermentation studies. The systematic overexpression of transcription factors (TFs) associated with biosynthetic gene clusters found in the genome of Burkholderia thailandensis E264 identified a set of TFs that, when overexpressed, alter the secondary metabolome of this bacterium. The isolation and characterization of burkholdacs A and B, two new acyldepsitripeptide histone deacetylase inhibitors produced by B. thailandensis overexpressing the TF bhcM, is reported.
Project description:Burkholderia thailandensis E264 is a potential non-pathogenic substitute for producing rhamnolipid biosurfactant, replacing the pathogenic Pseudomonas aeruginosa. However, it has low rhamnolipid production and longer fermentation time. We have earlier suggested that media supplementation with exogenous quorum sensing (QS) molecules could lead to early onset of biosynthesis and increased rhamnolipid yield. Here, we assessed the effect of single, double or triple mutations in the various QS systems of B. thailandensis on rhamnolipid production, with the view to see which system(s) have the most impact on rhamnolipid yield and subsequently use the QS molecule to potentially increase yield in the wild-type B. thailandensis. The triple mutant strain had a rhamnolipid yield of 4.46 ± 0.345 g/l at 240 h of fermentation which was significantly higher than that of the wild type (0.94 ± 0.06 g/l), an unexpected outcome. To gain more insight as to how this might occur, we studied substrate metabolism and energy storage in the form of polyhydroxyalkanoate (PHA) by both the triple mutant and the wild type. We observed increased glycerol metabolism and reduced PHA production in the triple mutant compared with the wild type. Glycerol concentration at 240 h and maximum PHA productivity (g/gDCB) were 8.76 g/l or 16.19 g/l and 21.80% or 31.4% in either the triple mutant or the wild type respectively. Complementation of the triple-mutant cultures with exogenous QS molecules restored rhamnolipid production to similar levels as the wild type. QS therefore is a potential target for increased rhamnolipid production in B. thailandensis.