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A Gram‐positive, aerobic, rod‐shaped mesophilic bacterium was isolated from birch wood, referred to as the AB strain. Allergological tests suggest that this strain may cause allergic alveolitis in sawmill workers. Employing a polyphasic taxonomic approach, the AB strain's 16S rRNA gene sequence showed high similarity to Microbacterium barkeri and M. oryzae, with 97.25% and 96.91%, respectively, a finding supported by rpoB and gyrB sequence analysis. Further genome sequence comparison with the closely related M. barkeri type strain indicated a digital DNA–DNA hybridization value of 25.5% and an average nucleotide identity of 82.52%. The AB strain's cell wall peptidoglycan contains ornithine, and its polar lipids comprise diphosphatidylglycerol, phosphatidylglycerol, and unidentified glycolipids. Its major fatty acids include anteiso C15:0, anteiso C17:0, and iso C16:0, while MK‐10 is its predominant respiratory quinone. Comprehensive analysis through 16S rRNA, whole‐genome sequencing, phenotyping, chemotaxonomy, and MALDI‐TOF MS profiling indicates that the AB strain represents a new species within the Microbacterium genus. It has been proposed to name this species Microbacterium betulae sp. nov., with ABT (PCM 3040T = CEST 30706T) designated as the type strain. [ABSTRACT FROM AUTHOR]

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The application of polyphasic taxonomic studies to identify several strains of Actinobacteria is presented. These microorganisms cause opportunistic infections relatively often (especially in immunocompromised patients), but their proper classification is difficult and they may be mistaken with other similar taxa. The article involves some clinical isolates properly identified by extended analysis, including simplified chromatographic methods (TLC, GLC). These procedures helped to establish a chemotaxonomic profile based on the well-grounded detection of chemical compounds of the bacterial cell envelope. Several components are useful taxonomic markers: the main amino acids of murein, sugars, and fatty acids and polar lipids, mainly phospholipids and glycolipids. The chemotaxonomy of Actinobacteria is a part of the contemporary classification of these microorganisms and should be applied in reference laboratories to avoid or minimize diagnostic and therapeutic error.

This study investigates the toxic effect of E(2)nonenal (trans-2-nonenal, T2N) and its conjugate with horse muscle myoglobin (Mb) tested on murine cell line L929 and human cell line A549, as well as the genotoxic effect of these compounds assayed by measuring of micronuclei in human cells K562. It is an aldehyde, which is occurring as the substance responsible for an off flavour in aged beers, but originates also from lipid oxidation in heat processed food. T2N is an aldehyde formed from linoleic acid as a secondary oxidation product. The modification of Mb with T2N was analyzed with the use of SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and electrospray ionization mass spectrometry (ESI-MS). Results from SDS-PAGE suggest that T2N substitutes Mb and additionally causes cross-linking with polymerization of Mb resulting in an insoluble fraction. The ESI-MS spectrum of the soluble fraction used in the toxicity tests, demonstrated that conjugation of T2N with Mb yielded Mb adducts with one residue of trans-2-nonenal per myoglobin molecule as the major fraction and adducts with different numbers of T2N molecules as minor fractions. In the cytotoxicity assay the T2N and its Mb conjugate causes 50% destruction of cells at the concentration 95-125 microg/ml and 200 microg/ml respectively, when L929 and A549 cell lines were used, whereas Mb control tested up to 2000 mg/ml was without any cytotoxic effect. In genotoxicity in vitro assay we have observed that the T2N and its Mb conjugate expressed the genotoxicity. The number of micronuclei in human K562 cells reached 26 +/- 2.16 promille (MN/1000 cells), comparing to 62 +/- 8.64 MN/1000 cells for the reference free T2N, whereas a control value was 10.33 +/- 1.25 MN/1000 cells. The studied compounds expressed also the apoptotic effect in K562 cells as the number of apoptotic cells increased to 44.67 +/- 4.92 promille for T2N-Mb, comparing to 168.67 +/- 37.28 promille for free T2N, whereas a control value was 30.33 +/- 1.36 promille for Mb. In these assays the T2N-Mb conjugate is several times more toxic in relation to control protein. Results indicate that T2N adducts with protein are potent to induce various cytotoxic and apoptotic effects when assayed in vitro tests. It suggests that higher level of such aldehyde might create in organism severe potential of toxicity.