


Volume 92, Nº 1 (2023)
REVIEWS
Fungal Azaphilone Pigments as Promising Natural Colorants
Resumo
Abstract—Microscopic fungi form and excrete numerous and diverse secondary metabolites, including pigments of various colors, which may be used as an alternative to chemical and plant colorants used in industry. Azaphilone compounds, first discovered in fungi of the genus Monascus, are among the promising classes of fungal pigments. The review analyzes the publications on formation of azaphilone-type pigments in Monascus fungi, as well as in Talaromyces and Aspergillus сavernicola. Brief information is provided concerning the antimicrobial, antitumor, anti-inflammatory, and hypolipidemic activities of azaphilone pigments. is given. Possible strategies for increasing the efficiency of the production process and directed synthesis of yellow, orange, and red pigments and their derivatives are discussed. In general, the review provides for assessment of the role of azaphilone pigments, as well as of the prospects and ways to expand their production for use as natural dyes in various fields.



EXPERIMENTAL ARTICLES
Sulfurospirillum tamanensis sp. nov., a Facultative Anaerobic Alkaliphilic Bacterium from a Terrestrial Mud Volcano
Resumo
Abstract—An alkaliphilic, facultatively anaerobic bacterium (strain T05bT) was isolated from a terrestrial mud volcano on the Taman Peninsula, Russia. The cells of the isolate were motile spirilla 0.5 µm thick and 1.5–2.5 µm long. Strain T05bT grew at 6–42°C (optimum at 30°C), pH 8.0–11.0 (optimum at 9.0), and 0–14% NaCl (wt/vol). Lactate, formate, malate, pyruvate, H2, elemental sulfur, sulfite, thiosulfate, and sulfide were used as electron donors; nitrate, fumarate, elemental sulfur, sulfite, thiosulfate, dimethyl sulfoxide, arsenate, and oxygen could be used as electron acceptors. Nitrate was reduced to ammonium. Malate, pyruvate, and fumarate were fermented. Microaerobic growth was possible at up to 3% О2 (vol/vol). Strain T05bT did not use sulfate and Fe(III) as electron acceptors, was unable of elemental sulfur, sulfite, or thiosulfate disproportionation, and did not ferment glucose, fructose, sucrose, lactate, formate, maleate, yeast extract, or peptone. The predominant fatty acids were C16:1 ω7 (45.9%), C16:0 (25.8%), and C18:1 ω7 (20.9%). The genome of strain T05bT was 2.46 Mb in size and had the G + C DNA content of 45.5%. It contained the genes encoding the following enzymes of energy metabolism: Nap nitrate reductase periplasmic complex, Phs/Psr thiosulfate/polysulfide reductase, Sqr sulfide:quinone oxidoreductase, and Arr respiratory arsenate reductase. Ac-cording to analysis of the 16S rRNA gene nucleotide sequence, strain T05bT exhibited 98.61% similarity to the type strain of Sulfurospirillum alkalitolerans (phylum “Campylobacterota”). Based on its phenotypic characteristics and the results of phylogenetic analysis, assignment of the isolate to a new Sulfurospirillum species, Sulfurospirillum tamanensis sp. nov., is proposed, with the type strain T05bT (=DSM 112596T = VKM B-3538T).



Leucosporidium egoroviorum f.a., sp. nov., a New Yeast Species Isolated from Zucchini
Resumo
Abstract—Leucosporidium egoroviorum f.a., sp. nov., a new anamorphic species of the basidiomycetous yeasts, was isolated as an endophyte from the fruits of Cucurbita pepo subsp. pepo (zucchini). According to its genetic, physiological, and morphological characteristics, the new species differed significantly from the closely related species L. fellii, L. intermedium, and L. krtinense. The holotype of the new specise, KBP Y-6804T, is preserved in a metabolically inactive state; its isotype strains are VKM Y-3065, DSM 113574, and CBS 17590. The MycoBank number is MB 842805.



State of Cyanobacteria Arthrospira platensis and of Associated Microflora during Long-Term Storage in the State of Anhydrobiosis
Resumo
Abstract—The biochemical composition of Arthrospira (Spirulina) platensis (Nordstedt) Gomont after long-term storage in the state of anhydrobiosis (4 years, 17 years) was determined by the standard methods. It was shown that protein content (55.3–61.2%) and total carbohydrates content (13.0–15.6%) in cyanobacterial cells were in agreement with the data known from the literature and with our results obtained at the onset of storage. The biomass had low content of free nucleotides (1.8–2.6%), lipids (1.3–11.0%), and especially pigments (0.5–1.3, 0.03–0.12, 1.4–2.0, 0.03–0.05% for chlorophyll a, carotenoids, C-phycocyanin, and allophycocyanin, respectively). The content of nucleic acids content was 3.1–24.0 and 0.11–0.16% for RNA and DNA, respectively. Microscopic examination of A. platensis (17 years of storage) showed high numbers of irreversibly damaged and dead cells (34.2 and 65.8%, respectively). To determine the quantitative and morphological parameters of associated microflora, a complex physicochemical treatment (methanol, ultrasound, and centrifugation) of the reactivated cyanobacterial suspension proved the most efficient. Three main groups were distinguished in the morphological structure of the microbiome (rod-shaped, rounded, and convoluted forms). The community was dominated by rod-shaped forms: large and small rods accounted for 60.5 and 14.4%, respectively. Mycelial forms (thin filaments), cocci, and convoluted forms were less common. On average, the volume of a bacterial cell was 0.27 ± 0.04 µm3. The contribution of bacteria to the biomass of A. platensis varied from 3.3 to 11.3% (8.3 ± 4.4% on average) of the dry weight of A. platensis. It has been suggested that the biochemical parameters and viability of cyanobacteria were affected by the accompanying microflora.



Detection of Microcystin-Producing Cyanobacteria Microcystis, Planktothrix, and Dolichospermum Using Multiprimer Amplification of the mcy Genes
Resumo
Abstract—A multiprimer PCR-based technique for the joint molecular detection of microcystin-producing planktonic cyanobacteria of the genera Microcystis, Planktothrix and Dolichospermum was developed. To amplify the mcy genes of microcystin biosynthesis, three pairs of genus-specific primers were selected, while the fourth pair was used to amplify the inter-gene spacer (IGS) cpcBA acting as an inner positive control for the presence of cyanobacterial DNA in the analyzed samples. Four PCR products of predicted size were successfully amplified using a mixture of DNA templates isolated from microсystin-producing strains of M. aeruginosa, P. agardhii, and field colonies of D. lemmermannii colonies retrieved from the environment, as well as аn environmental DNA template from lake plankton. The proposed multiprimer PCR-based approach may be used to design convenient test systems for monitoring aquatic ecosystems to prevent and/or assess the risk of accumulation of harmful cyanobacterial toxins.



Quorum Sensing in Chromobacterium subtsugae (Previously – C. violaceum) Is Inhibited by Gamma-Lactones, the Minor Components of Eucalyptus Leaf Extract
Resumo
Abstract—The goal of the study was to investigate the mechanism of quorum sensing (QS) inhibition in the model bacterium Chromobacterium subtsugae 026 (previously – C. violaceum 026) by Eucalyptus viminalis Labill leaf extract, and to identify the plant-derived components that provide this biological activity. The raw extract showed pronounced anti-QS activity within a broad concentrations range which were an order of magnitude lower than required for bacterial growth suppression (the MIC50/EC50 ratio of 43.6). Chemical analysis of the extract revealed six small plant-derived molecules: pyrogallol, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-1, p-cymene, 4-((1E)-3-hydroxy-1-propenyl)-2-methoxyphenol, gallic and palmitic acids, whose inhibitory effect on QS in Chromobacterium spp. has previously been shown by in vitro experiments or predicted by in silico models. In addition, minor components γ-caprolactone and γ-octanolactone, structurally similar to acylated homoserine lactones, QS autoinducers in Chromobacterium spp., were found in the extract. Chemically synthesized analogs of these molecules showed anti-QS activity in the C. subtsugae 026 bioassay (ЕС50 = 354.2 and 145.6 µg/mL, respectively). Enrichment of the E. viminalis leaf extract with γ-caprolactone or γ-octanolactone significantly increased the anti-QS activity of these compositions, which was determined by isobolographic analysis as additive or superadditive effects.



Comparative Assessment of Stress Responses of the Microalgae Prorocentrum cordatum (Ostenfeld) Dodge and Dunaliella salina (Teod.) to the Presence of Copper Nanoparticles
Resumo
Abstract—Comparative assessment of stress responses of two microalgal species differing in their cell structure and habitats, Prorocentrum cordatum and Dunaliella salina, to the presence of copper oxide nanoparticles (NP) in the medium was carried out. The nanoparticles were found to have a similar effect on both species. Their toxic effect resulted in progressing production of reactive oxygen species in the algal cells, while their specific growth rates decreased, probably due to Cu2+ release from the oxide or to penetration of some nanoparticles into the cells. NP mechanical impact resulted in their aggregation at the cell surface and deformation of the cell envelopes. The presence in the toxicant in the medium caused a reliable increase in cell volume, plasmalemma perforation, and predominance of deformed cells of irregular shape in the cultures. Two species exhibited different resistance to CuO NP. The sublethal and lethal concentrations for P. cordatum were 400 and 520 µg/L, respectively, compared to 3000 and 3750 µg/L for D. salina. The possible causes for resistance of D. salina to CuO NP are discussed. D. salina is able to produce ligands (phytochelatins and metallothionenis) in high concentrations, which may be released into the medium and bind the Cu2+ ions. Moreover, the habitats of D. salina are extreme, which may promote its stress tolerance, probably a genetically determined feature and a part of their overall resistance to other contaminants. High resistance of D. salina to CuO NP may also be due to its ability to secrete extracellular polymers under stress conditions; they may form a protective layer preventing the interaction between the microalgae and NP. Application of P. cordatum for biomonitoring of NP-contaminated seawater environments is proposed. D. salina may be promising for water bioremediation.



Biocidal Activity of Chitosan Asparaginate Nanoparticles
Resumo
Abstract—The biological activity of chitosan asparaginate particles formed in the chitosan‒L-aspartic acid‒water system at the initial stage of phase separation was investigated. Cultivation of Staphylococcus aureus 209 P and Escherichia coli 113-13 in the medium supplemented with nanoparticles resulted in massive death of bacterial cultures. The biocidal activity against gram-positive bacteria was most pronounced. Biological tests revealed high biocompatibility of chitosan nanoparticles and their ability to accelerate the proliferative activity of the cultures of epidermal and epithelial cells. Our results indicate that chitosan asparaginate nanoparticles are promising for medico-biological and pharmaceutical applications.



The Effect of Atranes on the Growth of Rhodococcus qingshengii VKM Ac-2784D in the Presence of Various Carbon Sources and on Its Ability to Degrade Naphthalene
Resumo
Abstract—Rhodococcus qingshengii VKM Ac-2784D isolated from the rhizosphere of Elytrigia repens, is a promising oil degrader. To increase its biotechnological potential, the effect of atranes (potential growth stimulants) on its growth and naphthalene degradation was studied. The effect of the studied atranes on R. qingshengii VKM Ac-2784D was shown to depend on the nature of the carbon source: addition of atranes had practically no effect on the growth rate of bacteria in the rich BTN medium; in the media 8E and 8E with glucose, it baused short-term activation of growth, characterized by a shorter lag phase. In the presence of naphthalene, atranes had a predominantly negative effect on the growth of R. qingshengii VKM Ac-2784D. The studied atranes had a negative effect on the rate of naphthalene decomposition by R. qingshengii VKM Ac-2784D, and also decreased the cell wall hydrophobicity and the synthesis of extracellular biosurfactants. It may therefore be assumed that the studied compounds will have a negative effect on the rate of naphthalene decomposition by this microorganism.



Microbial Destruction of Polypropylene and Polyvinylchloride Samples under the Anaerobic Conditions
Resumo
Abstract—The most advantageous characteristic of the materials made of synthetic polymers, such as their resistance to biodegradation, is simultaneously the reason for their accumulation and environmental pollution. Nevertheless, some type of plastics under aerobic conditions undergo slow microbial degradation, however, there is lack of information on the anaerobic degradation of plastics. In this work, we studied the growth of anaerobic moderately thermophilic (55°C) consortiums in the presence of samples made of polypropylene (PP) and polyvinyl chloride (PVC). It was shown that the microbial biomass increased compared to the control, as well as anaerobic decomposition products (CO2, H2, and H2S) were detected, and the total weight of the plastics decreased by 4.4% (PP) and 6.5% (PVC) compared to the control. Bacterial cells adhere and form colonies and biofilms on the surface of the plastic materials. An analysis of the composition of microbial communities showed an increased number of anaerobic hydrolytics of the genus Tepidimicrobium, potential syntrophic bacteria of the genus Tepidanaerobacter, and especially sulfate-reducing bacteria (Desulfohalotomaculum). With help of differential scanning calorimetry and Fourier spectroscopy it was revealed that the decrease in the mass of plastic mainly occurred due to the hydrolysis of additives (plasticizers). The role of such microbial communities in the aquatic environment and anaerobic layers of the municipal solid waste landfills, where PP and PVC plastics can be destructed under the elevated temperatures of anaerobic conditions, is discussed.



SHORT COMMUNICATIONS
Genes of NAD+-Dependent Formate Dehydrogenases in Taxonomy of Aerobic Methylotrophic Bacteria of the Genus Ancylobacter
Resumo
Abstract—Comparative phylogenetic analysis of NAD+-dependent formate dehydrogenases (NAD+–FDH) genes, which have been detected in all available genomes of methylotrophs of the genera Ancylobacter, Starkeya and Angulomicrobium, as well as in other members of the family Xanthobacteraceae (Xanthobacter, Aquabacter, Azorhizobium), was carried out. The position of Xanthobacteraceae on the tree constructed based on comparison of NAD+–FDH amino acid sequences was found to correlate with the 16S rRNA gene-based phylogeny. The sequences of the NAD+–FDH proteins of the genera Ancylobacter, Starkeya, and Angulomicrobium exhibited 87.8–98.3% identity, indicating that this protein is very conservative within this group of methylotrophs. For the first time, analysis of the NAD+–FDH functional genes is recommended as a supplementary criterion for interspecies differentiation between methylotrophic bacteria of the genus Ancylobacter.



Articles
Авторский указатель тома 91, 2022 г.


