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Persistent environmental pollutants are a growing problem around the world. The effective control of the pollutants is of great significance for human health. Some microbes, especially Arthrobacter, can degrade pollutants into nontoxic substances in various ways. Here, we review the biological properties of Arthrobacter adapting to a variety of environmental stresses, including starvation, hypertonic and hypotonic condition, oxidative stress, heavy metal stress, and low-temperature stress. Furthermore, we categorized the Arthrobacter species that can degrade triazines, organophosphorus, alkaloids, benzene, and its derivatives. Metabolic pathways behind the various biodegradation processes are further discussed. This review will be a helpful reference for comprehensive utilization of Arthrobacter species to tackle environmental pollutants.

Swainsonine is an indolizidine alkaloid that has been found in locoweeds and some fungi. Our previous study demonstrated that Arthrobacter sp. HW08 or its crude enzyme extract could degrade swainsonie efficiently. However, the mechanism of swainsonine degradation in bacteria remains unclear. In this study, we used label-free quantitative proteomics method based on liquid chromatography-electrospray ionization-tandem mass spectrometry to dissect the mechanism of swainsonine biodegradation by Arthrobacter sp. HW08. The results showed that 129 differentially expressed proteins were relevant to swainsonine degradation. These differentially expressed proteins were mostly related to the biological process of metabolism and the molecular function of catalytic activity. Among the 129 differentially expressed proteins, putative sugar phosphate isomerase/epimerase A1R5X7, Acetyl-CoA acetyltransferase A0JZ95, and nicotinamide adenine dinucleotide phosphate (NADP)-dependent alcohol dehydrogenase A1R6C3 were found to contribute to the swainsonine degradation. Notably, NADP-dependent alcohol dehyrodgenase A1R6C3 appeared to play a major role in degrading swainsonine, but not as much as Arthrobacter sp. HW08 did. Collectively, our findings here provide insights to understand the mechanism of swainsonine degradation in bacteria.

In order to isolate and characterize 2,2,6,6-Tetramethyl-4-piperidone (TMPD)- degrading bacteria and to select the optimal degrading conditions, different bacterial types which can degrade TMPD were isolated from soil samples. Three strains (LF-1, LF-2 and LF-3) showed strong biodegradation ability by UV-visible spectrophotometer analysis. Morphological and biochemical analyses, as well as 16S rRNA gene sequence comparisons of three strains were further carried out. They were identified as Klebsiella oxytoca, Staphylococcus pasteur and Bacillus flexus, respectively. K. oxytoca, S. pasteur and B. flexus had degrading capabilities for TMPD in mineral salt medium of 80.9, 69.8 and 64.9%, respectively, during 24 days of incubation. Maximum degrading rates were obtained by an initial concentration of the TMPD of 200 mg/L, an incubation temperature of 30°C, and constant aeration (180 rev/min). In conclusion, K. oxytoca, S. pasteur and B. flexus show their potentials in TMPD detoxifying and in protecting the TMPD contaminated environment. Key words: 2,2,6,6-Tetramethyl-4-piperidone (TMPD), biodegradation, Klebsiella oxytoca, Staphylococcus pasteur, Bacillus flexus.

Locoweeds including the toxic species of Astragalus spp and Oxytropis spp. are widely distributed in the western region of China and result in a chronic neurological disease known as locoism in animals. To determine the presence of swainsonine-producing fungal endophyte of major locoweed species in China, endophytes were isolated from 8 locoweed species that including A. variabilis, A. strictus, O. glacialis, O. kansuensis, O. ochrocepala, O. sericopetala, O. glabra and O. latibracteata. Seven species of locoweed were confirmed contain substantial amounts of swainsonine and infect swainsonine-producing fungal endophyte. These endophytes were classified as Undifilim oxytropis according to the fungal morphology and phylogenetic analysis based on sufficient ITS sequences. PCR-RFLP analysis of IGS region showed that the interspecific or intraspecific variations were present among the endophytes from different locoweed species.

Golgi α-mannosidase II (GMII), a key glycosyl hydrolase in the N-linked glycosylation pathway, has been demonstrated to be closely associated with the genesis and development of cancer. In this study, we cloned cDNA-encoding Capra hircus GMII (chGMII) and expressed it in Pichia pastoris expression system. The chGMII cDNA contains an open reading frame of 3432 bp encoding a polypeptide of 1144 amino acids. The deduced molecular mass and pI of chGMII was 130.5 kDa and 8.04, respectively. The gene expression profile analysis showed GMII was the highest expressed gene in the spleen. The recombinant chGMII showed maximum activity at pH 5.4 and 42 °C and was activated by Fe(2+), Zn(2+), Ca(2+), and Mn(2+) and strongly inhibited by Co(2+), Cu(2+), and EDTA. By homology modeling and molecular docking, we obtained the predicted 3D structure of chGMII and the probable binding modes of chGMII-GnMan5Gn, chGMII-SW. A small cavity containing Tyr355 and zinc ion fixed by residues Asp290, His176, Asp178, and His570 was identified as the active center of chGMII. These results not only provide a clue for clarifying the catalytic mechanism of chGMII but also lay a theoretical foundation for subsequent investigations in the field of anticancer therapy for mammals.

The endophytic fungus XJ-AC03, which was isolated from the healthy roots of Aconitum leucostomum, produced aconitine when grown in potato dextrose agar (PDA) medium. The presence of aconitine was confirmed by the chromatographic and spectroscopic analyses. The yield of aconitine was recorded as 236.4 μg/g by high performance liquid chromatography (HPLC). The mass spectrometry was shown to be identical to authentic aconitine. Further analysis with nuclear magnetic resonance (NMR) spectroscopy to show the chemical structure of the fungal aconitine indicated that the fungal aconitine produced an NMR spectrum identical to that of authentic aconitine. Strain XJ-AC03 was identified as Cladosporium cladosporioides by its characteristic culture morphology and ITS rDNA sequence analysis.