A simple method for differentiation of Propionibacterium acnes and Propionibacterium propionicum

Identification of environmental Actinobacteria in buildings by means of chemotaxonomy, 16S rRNA sequencing, and MALDI-TOF MS

Actinobacteria are abundant in soil and other environmental ecosystems and are also an important part of the human microbiota. Hence, they can also be detected in indoor environments and on building materials, where actinobacterial proliferation on damp materials can indicate moisture damage. The aim of this study was to evaluate the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of 28 environmental strains of Actinobacteria isolated from building materials and indoor and outdoor air samples, mainly collected in the context of moisture damage investigations in buildings in Finland. The 16S rRNA gene sequencing and chemotaxonomic analyses were performed, and results were compared with the MALDI-TOF MS Biotyper identification. Using 16S rRNA gene sequencing, all isolates were identified on the species or genus level and were representatives of Streptomyces, Nocardia, and Pseudonocardia genera. Based on MALDI-TOF MS analysis, initially, 11 isolates were identified as Streptomyces spp. and 1 as Nocardia carnea with a high identification score. After an upgrade in the MALDI-TOF MS in-house database and re-evaluation of mass spectra, 13 additional isolates were identified as Nocardia, Pseudonocardia, and Streptomyces. MALDI-TOF MS has the potential in environmental strain identification; however, the standard database needs to be considerably enriched by environmental Actinobacteria representatives.

IMPORTANCE

The manuscript addresses the challenges in identifying environmental bacteria using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) Biotyper-based protein profiling. The matter of the studies-actinobacterial strains-has been isolated mostly from building materials that originated from a confirmed moisture-damaged situation. Polyphasic taxonomy, 16S RNA gene sequencing, and MALDI-TOF mass spectrometry were applied for identification purposes. In this experimental paper, a few important facts are highlighted. First, Actinobacteria are abundant in the natural as well as built environment, and their identification on the species and genus levels is difficult and time-consuming. Second, MALDI-TOF MS is an effective tool for identifying bacterial environmental strains, and in parallel, continuous enrichment of the proteomics mass spectral databases is necessary for proper identification. Third, the chemical approach aids in the taxonomical inquiry of Actinobacteria environmental strains.

Lipids of Dietzia sp. A14101. Part II: A study of the dynamics of the release of surface active compounds by Dietzia sp. A14101 into the medium

Dietzia sp. A14101 isolated from an oil reservoir model column was found to induce a strong decrease of the interfacial tension (IFT) in hydrocarbon-water mixtures in the presence of the intact bacterial cells (Kowalewski et al., 2005). The strain was shown to be able to degrade a wide range of hydrocarbon substrates (Bødtker et al., 2009). Further studies showed that the surface-active compounds tentatively identified as glycolipids were produced by Dietzia sp. A14101 on non- and water-immiscible -hydrocarbon substrates, Part I (Hvidsten et al., 2017). The results suggested that biosurfactant (BS) was a mixture of several isomers. The study presented here is aimed to investigate whether BS are secreted into the aqueous medium, and if so, then at which phase of the culture growth and in which amounts - the dynamics of the BS release in incubations on water-immiscible hydrocarbons. Two methods of BS extraction from the medium were attempted and compared: a liquid-liquid extraction (LLE) and precipitation by acid. For qualitative and semi-quantitative assessment, gas chromatography-mass spectrometry (GC/MS), thin-layer chromatography (TLC), liquid chromatography-mass spectrometry (LC-MS), surface tension measurements (SFT), emulsification (E₂₄) and oil-spreading tests were employed. The results indicated that BS only partially were secreted into the medium. Detectable amounts of glycolipids in media were first identified during the exponential growth phase. However, only a slight decrease of SFT was observed in the cell-free medium. The emulsification index values of the sampled material were lower than those reported for related strains. The results suggested that most of the BS produced by Dietzia sp. A14101 remains cell-bound during the culture development in a batch mode and only a narrow range of the BS isomers can be detected in small amounts in media.

Lactobacillus johnsonii glycolipids, their structure and immunoreactivity with sera from inflammatory bowel disease patients

Structural studies of the major glycolipids produced by two Lactobacillus johnsonii (LJ) strains, LJ 151 isolated from intestinal tract of healthy mice and LJ 142 isolated from mice with experimentally induced inflammatory bowel disease (IBD), were performed. Two major glycolipids, GL1 and GL2, were present in lipid extracts from L. johnsonii 142 and 151 strains. Glycolipid GL1 has been identified as β-D-Glcp-(1→6)-α-D-Galp-(1→2)-α-D-Glcp-diglyceride and GL2 as α-D-Galp-(1→2)-α-D-Glcp-diglyceride. The main fatty acid residues identified by gas-liquid chromatography-mass spectrometry were palmitic, stearic and lactobacillic acids. Besides structural elucidation of the major glycolipids, the aim of this study was to determine the immunochemical properties of these glycolipids and to compare their immunoreactivity to that of polysaccharides obtained from the same strains. Sera from rabbits immunized with bacterial cells possessed much higher serological reactivity with polysaccharides than with glycolipids. Inversely, reactivity of the glycolipids with human sera from patients with IBD was much higher than that determined for the polysaccharides, while reactivity of glycolipids with human sera from healthy individuals was much lower than one measured for the polysaccharides. Results indicate that glycoconjugates from Lactobacillus cell wall act as antigens and may represent new IBD diagnostic biomarkers.

An airborne actinobacteria Nocardiopsis alba isolated from bioaerosol of a mushroom compost facility

Actinobacteria are widely distributed in many environments and represent the most important trigger to the occupant respiratory health. Health complaints, including hypersensitivity pneumonitis of the workers, were recorded in a mushroom compost facility (MCF). The studies on the airborne bacteria were carried out to find a possible microbiological source of these symptoms. Culture analysis of compost bioaerosols collected in different location of the MCF was performed. An assessment of the indoor microbial exposure revealed bacterial flora of bioaerosol in the mushroom compost facility represented by Bacillus, Geobacillus, Micrococcus, Pseudomonas, Staphylococcus spp., and actinobacterial strain with white aerial mycelium. The thermotolerant actinobacterial strain of the same morphology was repeatedly isolated from many locations in MCF: air, compost sample, and solid surface in production hall. On the base of complex morphological, chemotaxonomic, and phylogenetic characteristics, the isolate has been classified as Nocardiopsis alba. Dominant position of N. alba in microbial environment of the mushroom compost facility may represent an indicator microorganism in compost bioaerosol. The bioavailability of N. alba in mushroom compost facility creates potential risk for the health of workers, and the protection of respiratory tract and/or skin is strongly recommended.

Synergistic effect of high and low molecular weight molecules in the foamability and foam stability of sparkling wines

The foam of sparkling wines is a key parameter of their quality. However, the compounds that are directly involved in foam formation and stabilization are not yet completely established. In this work, seven sparkling wines were produced in Bairrada appellation (Portugal) under different conditions and their foaming properties evaluated using a Mosalux-based device. Fractionation of the sparkling wines into four independent fractions, (1) high molecular weight material, with molecular weight higher than 12 kDa (HMW), (2) hydrophilic material with molecular weigh between 1 and 12 kDa (AqIMW), (3) hydrophobic material with molecular weigh between 1 and 12 kDa (MeIMW), and (4) hydrophobic material with a molecular weight lower than 1 kDa (MeLMW), allowed the observation that the wines presenting the lower foam stability were those that presented lower amounts of the MeLMW fraction. The fraction that presented the best foam stability was HMW. When HMW is combined with MeLMW fraction, the foam stability largely increased. This increase was even larger, approaching the foam stability of the sparkling wine, when HMW was combined with the less hydrophobic subfraction of MeLMW (fraction 3). Electrospray tandem mass spectrometry (ESI-MS/MS) of fraction 3 allowed the assignment of polyethylene glycol oligomers (n = 5-11) and diethylene glycol 8-hydroxytridecanoate glyceryl acetate. To observe if these molecules occur in sparkling wine foam, the MeLMW was recovered directly from the sparkling wine foam and was also analyzed by ESI-MS/MS. The presence of monoacylglycerols of palmitic and stearic acids, as well as four glycerylethylene glycol fatty acid derivatives, was observed. These surface active compounds are preferentially partitioned by the sparkling wine foam rather than the liquid phase, allowing the inference of their role as key components in the promotion and stabilization of sparkling wine foam.

Structural and serological characterization of the major glycolipid from Rothia mucilaginosa

Structural studies on the major glycolipid isolated from Rothia mucilaginosa were carried out utilising specific chemical degradation, NMR spectroscopy and matrix-assisted laser-desorption/ionization time of flight mass spectrometry (MALDI TOF-MS). The glycolipid was found to be a dimannosylacylmonoglyceride in which the carbohydrate part was the glycerol-linked dimannoside alpha-D-Manp-(1-->3)-alpha-D-Manp-(1-->3)-sn-Gro (Man A-Man B-Gro), of which Man B was esterified at O-6 by a fatty acid residue. A second fatty acid substituted the secondary methylene position of the glycerol residue, in contrast to the glycolipid previously found in R. dentocariosa and Saccharopolyspora strains, in which the second fatty acid esterified the primary methylene position of glycerol. Results of the ELISA experiment with rabbit specific antibacterial sera indicate that these two major glycolipids are antigenic, and the patterns of serological reactivity are similar but not identical.

Novel bacterial polar lipids containing ether-linked alkyl chains, the structures and biological properties of the four major glycolipids from Propionibacterium propionicum PCM 2431 (ATCC 14157T)

Propionibacterium propionicum belongs to the "acnes group" of propionibacteria, which is currently considered as clinically important because of its growing potential in infections, in particular with those connected with immune system dysfunctions. Propionibacteria are thought to be actinomycete-like microorganisms and may still cause diagnostic difficulties. The chloroform-methanol extracts of the cell mass of P. propionicum (type strain) gave in TLC analysis the characteristic glycolipid profile containing four major glycolipids, labeled G(1) through G(4). These polar lipids were found to be useful chemotaxonomic markers to differentiate P. propionicum from other cutaneous propionibacteria, in particular from strains of the acnes group. Glycolipids G(1)-G(4) were isolated and purified using gel-permeation chromatography, TLC, and high performance liquid chromatography, and their structures were elucidated by compositional and methylation analyses, specific chemical degradations, MALDI-TOF mass spectrometry, and (1)H NMR and (13)C NMR spectroscopy, including HMBC, TOCSY, HMQC, and NOESY experiments. Glycolipids G(2) and G(3) possess as backbone alpha-d-Glcp-(1 --> 3)-alpha-d-Glcp-(1 --> 1)-Gro (Gro, glycerol), in which position O-2 of the glycerol residue is acylated by a fatty acid (mainly C(15):0) while O-3 is substituted by an alkyl ether chain. In glycolipid G(3), an additional fatty acyl chain was linked to O-6 of the terminal glucose residue. Glycolipid G(4) was structurally related to G(2) but devoid of one glucose residue. Glycolipid G(1) was isolated in small amounts, and its structure was therefore deduced from MALDI-TOF-MS experiments alone, which revealed that it possessed the structure of G(2) but was lacking one fatty acid residue. In studies on the biological properties of P. propionicum glycolipids, the anti-P. propionicum rabbit antisera reacted in dot enzyme-immunoblotting test with G(2) and G(3). Glycolipid G(3) was able to induce the delayed type of hypersensitivity. The results indicated that these novel ether linkage-containing polar glycolipids are immunogenic and possibly active in hypersensitivity, and thus, in pathogenesis.

Structure of the major glycolipid from Rothia dentocariosa

Structural studies of the major glycolipid isolated from Rothia dentocariosa were carried out by specific chemical degradation and nuclear magnetic resonance spectroscopy. The glycolipid was found to be a dimannosylacylmonoglyceride in which the carbohydrate part was the glycerol-linked dimannoside alpha-D-Manp-(1-->3)-alpha-D-Manp-(1-->3)-sn-Gro, and the internal mannose was esterified at C-6 by fatty acid residue. The other fatty acyl chain substituted the primary methylene position of glycerol. The occurrence of this glycolipid is limited to the related microorganisms. The structural characteristics can facilitate the differentiation of some genera.

Rare, suppurative pulmonary infection caused by Nocardiopsis dassonvillei recognized by glycolipid markers

An opportunistic actinomycete was isolated as the only etiological agent of a severe, suppurative pulmonary infection. The strain was rapidly recognised as Nocardiopsis by the taxonomically important and immunologically active glycolipid markers (G1 and G2). Identification of the clinical isolate, from a group of actinomycetes mainly known as soil habitants, was definitely proved by chemotaxonomic studies (cell wall/sugar, phospholipid and fatty acid types) as well as by genomic data (GC content, DNA-DNA reassociation). The level of DNA-DNA homology of the clinical actinomycete, in comparison with other reference members of this genus, revealed the highest (88%) relatedness to Nocardiopsis dassonvillei. The results confirmed the value and generic specificity of glycolipid markers from Nocardiopsis, the first time used for rapid recognition of a clinical strain causing a nocardiosis-like disease.

Structural studies of the major glycolipid from Saccharopolyspora genus

A major glycolipid was isolated from the well characterized Saccharopolyspora species, S. hirsuta, S. rectivirgula, S. erythraea and one not completely identified strain (Saccharopolyspora sp.). On the basis of sugar and methylation analysis, specific enzymatic and chemical degradations of the carbohydrate moiety, its FAB mass spectrometry and NMR spectroscopy characterizations, the carbohydrate part was shown to be the glycerol linked dimannoside alpha-D-Manp-(1-->3)-alpha-D-Manp-(1-->1/3)Gro. The internal mannose residue is esterified at C-6 by one fatty acid residue, whereas another fatty acyl chain substitutes the primary methylene position of glycerol. The main fatty acyl residues are anteiso-branched heptadecanoic acid and the iso-branched fatty acids iso-17:0, iso-16:0, and iso-18:0, with the former species being predominant. The major glycolipid has potential value for taxonomic and diagnostic purposes, especially in the specific diagnosis of farmer's lung disease.