Project description:In this work, we investigated intracellular pH homeostasis within the thermoacidophilc methanotroph Methylacidiphilum sp. RTK17.1. Our findings show the proton motive force for this species is primarily generated by a pH gradient across the cellular membrane. In batch experiments, the addition of formate resulted in no observable cell growth and, correspondingly, acidification of the cytosol, decreased formate dehydrogenase activity and (presumably) cell-death. Nevertheless, we were able to demonstrable growth on formate as the sole source of metabolizable energy was possible in steady-state (continuous) cultures following the transition from methanol to formate. Under these conditions, biomass productivity yields on formate were 63% less than for growth on methanol. Transcriptome analysis revealed key genes associated with pH homeostasis, methane, methanol and formate metabolism were significantly regulated in response to growth on formate. Collectively, these results suggest environmental formate represents a utilisable source of energy/carbon to the acidophilic methanotrophs during periods of methane starvations and highlights potential short-comings of traditional batch-culture physiological characterisation studies in acidophilic species.
Project description:The purpose of this study was to identify genes that are differentially expressed upon prrA overexpression, to reveal the impact of PrrA on global transcription in acidic pH and/or high chloride conditions.
Project description:The purpose of this study was to understand how prevention of serine/threonine protein kinase (STPK) phosphorylation of PrrA impacts PrrA modulation of M. tuberculosis transcriptional response to acidic pH and high chloride levels.
Project description:Denmark has an extraordinarily large and well-preserved collection of archaeological skin garments found in peat bogs, dated to approximately 920 BC - AD 775. These objects provide not only the possibility to study prehistoric skin costume and technologies, but also to investigate the animal species used for production of skin garments. Until recently, species identification of archaeological skin was mainly performed by light and scanning electron microscopy or analysis of ancient DNA. However, the efficacy of these methods can be limited due to the harsh, mostly acidic environment of peat bogs leading to morphological and molecular degradation within the samples. We compared species assignment results of twelve archaeological skin samples from Danish bogs using Mass Spectrometry (MS)-based peptide sequencing, against results obtained using light and scanning electron microscopy
Project description:Leptospirillum ferriphilum is an important acidophilic ferrous iron-oxidizing species for bioleaching or biooxidation to win metals like copper or gold, respectively. L. ferriphilum is inhibited by elevated conentrations of chloride. In the present study, the type strain of L. ferriphilum (i.e. strain DSM 14647) by subcultivation in presence of increasing chloride concentrations was adapted to tolerate higher concentrations of NaCl. The adapted culture was grown in presence of 180 mM NaCl or and the non-adapted culture without NaCl, and both were harvested in the late exponential phase. Total RNA was isolated and checked for quality and integrity. For each of the two conditions three RNA preparations of high quality (integrity number above 7) were pooled. Ribosomal RNA was depleted. DNA libraries for paired-end sequencing on an Illumina MiSeq were generated with a TruSeq stranded mRNA library prep kit (Illumina). Among the genes up-regulated were those coding for proteins likely involved in intracellular pH regulation, response to reactive oxygen species, and Fe-S cluster biosynthesis. Among the genes down-regulated in presence of chloride were those related to lipopolysaccharide and peptidoglykane synthesis, and interestingly also those for (hydroxy) ectoine biosynthesis.
