Project description:The tertiary branched short-chain 2-hydroxyisobutyric acid (2-HIBA) has been associated with several metabolic diseases and lysine 2-hydroxyisobutyrylation seems to be a common eukaryotic as well as prokaryotic post-translational modification in proteins. In contrast, the underlying 2-HIBA metabolism has thus far only been detected in a few microorganisms, such as the betaproteobacterium Aquincola tertiaricarbonis L108 and the Bacillus group bacterium Kyrpidia tusciae DSM 2912. In these strains, 2-HIBA can be specifically activated to the corresponding CoA thioester by the 2-HIBA-CoA ligase HCL and is then isomerized to 3-hydroxybutyryl-CoA in a reversible and B12-dependent mutase reaction. Here, we demonstrate that the actinobacterial strain Actinomycetospora chiangmaiensis DSM 45062 degrades 2-HIBA and also its precursor 2-methylpropane-1,2-diol via acetone and formic acid by employing a thiamine pyrophosphate-dependent lyase. The corresponding gene is located directly upstream of hcl, which has previously been found only in operonic association with the 2-hydroxyisobutyryl-CoA mutase genes in other bacteria. Heterologous expression of the lyase gene from DSM 45062 in E. coli established a 2-hydroxyisobutyryl-CoA lyase activity in the latter. In line with this, analysis of the DSM 45062 proteome reveals a strong induction of the lyase-HCL gene cluster on 2-HIBA. Acetone is likely degraded via hydroxylation to acetol catalyzed by a MimABCD-related binuclear iron monooxygenase and formic acid appears to be oxidized to CO2 by selenium-dependent dehydrogenases. The presence of the lyase-HCL gene cluster in isoprene-degrading Rhodococcus strains and Pseudonocardia associated with tropical leafcutter ant species points to a role in degradation of biogenic volatile organic compounds.
Project description:During the rainy season in Thailand, specimens of Phallus chiangmaiensis sp. nov. and P. merulinus were collected from Chiang Mai and Samut Sakhon Provinces, respectively. Molecular phylogenetic analyses based on sequences of the nuclear ribosomal large subunit (LSU), nuclear ribosomal 5.8S gene including the internal transcribed spacer regions 1 and 2 (ITS), and the protein-coding gene atp6 (mitochondrial adenosine triphosphate [ATP] synthase subunit 6) support the placement of the new species within Phallus. Phallus chiangmaiensis has a well-developed white indusium and campanulated caps with reticulate surfaces. It differs morphologically from the related species, as supported by the phylogenetic data. Phallus merulinus is reported here as a species that was re-encountered in Thailand. The descriptions of the species are accompanied by illustrations of macro- and micro- morphological features, and a discussion of the related taxa is presented.
Project description:This study involved the characterization of AgNPs synthesized from soil isolate Streptomyces sp. SSUT88A and their antimicrobial activities. The strain SSUT88A revealed 98.8% similarity of the 16s rRNA gene to Streptomyces chiangmaiensis TA4-1T. The AgNPs were synthesized by mixing either intracellular or extracellular cell-free supernatant of strain SSUT88A with AgNO3. The synthesized AgNPs from intracellular cell-free supernatant and extracellular cell-free supernatant were designated as IS-AgNPs and ES-AgNPs, respectively. The IS-AgNPs showed maximum absorbance of UV-vis spectra at 418 nm, while ES-AgNPs revealed maximum absorbance at 422 nm. The TEM observation of synthesized AgNPs revealed a spherical shape with an average diameter of 13.57 nm for IS-AgNPs and 30.47 nm for ES-AgNPs. The XRD and XANES spectrum profile of both synthesized AgNPs exhibited similar spectrum energy, which corresponded to AgNPs. The IS-AgNPs revealed antimicrobial activity against clinical isolate drug-resistant bacteria (Acinetobacter baumannii, Escherichia coli 8465, Klebsiella pneumoniae 1617, and Pseudomonas aeruginosa N90PS), while ES-AgNPs had no antimicrobial activity. When compared to commercial AgNPs, IS-AgNPs exhibited antibacterial efficacy against all clinical isolate bacteria including A. baumannii, one of the most threatening multi-drug resistant strains, while commercial AgNPs did not. Thus, IS-AgNPs has potential to be further developed as an antimicrobial agent against drug-resistant bacteria.