The growing concern over the long-term persistence of plastic waste has driven research into biological methods of breaking down polymers. This study investigated a process that combines physicochemical pretreatment and biodegradation of low-density polyethylene (LDPE) using bacterial strains isolated from commercial compost. Four bacterial strains were genetically identified and classified as Actinomycetes. Exposure of LDPE to these selected strains resulted in a measurable reduction in polymer sample weight, accompanied by alterations in surface hydrophobicity. Furthermore, the chemical modifications at the films’ surfaces were confirmed by the spectra obtained by Fourier transform infrared spectroscopy (FTIR). The microbial colonisation of plastic surfaces plays a key role in the overall biodegradation process. The formation of a biofilm and the subsequent morphological changes on the LDPE surface were revealed by scanning electron microscopy (SEM). The modification of the polyethylene surface by nitric acid treatment was found to be a promising strategy for enhancing the LDPE degradation. The acid-treated films exhibited the greatest weight loss, the greatest increase in carbonyl index values, and the greatest change in hydrophobicity following microbial exposure. Moreover, it was found that biodegradation under these conditions resulted in the lowest levels of phytotoxic byproducts. The transformation of polyethylene surface properties—from hydrophobic to hydrophilic—combined with the presence of oxidized functional groups made it easier for microorganisms to degrade LDPE.

The genus Actinoplanes comprises 57 species (in February 2024) that are important components of ecosystems and are widely used in biotechnology, especially pharmaceuticals. Phylogenetic analysis of the family Micromonosporaceae (based on the 16S rRNA gene sequence) allowed us to group members of different genera into separate clades; however, the genus Actinoplanes was divided into three separate clades. Such phylogenetic heterogeneity could be due to the limitations of 16S rRNA gene analysis. In response to this heterogeneity, genomic phylogeny was performed. Phylogenomic reconstruction based on 324 single-copy orthologous genes allowed us to divide the genus Actinoplanes first into four clades and then, based on average nucleotide identity analysis, into five clades. Finally, chemotaxonomic analysis of each clade confirmed each clade’s distinctiveness and the necessity to reclassify the genus Actinoplanes. The obtained data allowed us to divide the genus Actinoplanes into five genera: Actinoplanes, Paractinoplanes, Winogradskya, Symbioplanes and Amorphoplanes.

Biol. Stud. 2019: 13(2); 29–40 • DOI: https://doi.org/10.30970/sbi.1302.603 PROKARYOTIC EXPRESSION AND PURIFICATION OF BIOACTIVE DEFENSIN 2 FROM PINUS SYLVESTRIS L.

A novel actinomycete strain, designated Pv 4-285^T, was isolated from rhizosphere sample collected from Phyllostachys viridiglaucescens growing in the Nikitsky Botanical Garden, Crimea, Ukraine. The strain Pv 4-285 ^T shared the highest 16S rRNA gene sequence similarity with Mumia xiangluensis NEAU-KD1^T. The genome size was 4.6 Mbp with a DNA G+C content of 70.43%. The isolate was Gram-stain-positive, non-spore-forming, non-motile and aerobic. Cells were observed to be irregularly rod-shaped. Pv 4-285^T was able to grow at 20–37 °C and at pH 6.0–9.0 and in the presence of up to 6% (w/v) NaCl. The predominant menaquinone was detected as MK-9(H₄). The polar lipid profile of strain Pv 4-285^T consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside and phosphatidylinositol. Pv 4–285 contained C_16:0, С_18:1 ω9c, 10-methyl C_18:0, C_17:0. While galactose, mannose and xylose were detected in strain Pv 4-285^T as the whole-cell sugars. Based on these differences, strain Pv 4-285^T (=DSM 118545^T =LMG 33743^T) should be classified as the type strain of a novel species of Mumia, for which the name Mumia qirimensis sp. nov. is proposed.

In this study, we present the genome sequence of Umezawaea sp. strain Da 62-37, which was isolated from the rhizosphere of Deschampsia antarctica E.Desv. (Galindez Island, maritime Antarctic). The de novo assembly produced one contig, with a length of 11,793,683 bp. AntiSMASH analysis indicated 49 biosynthetic gene clusters.