Состояние легочной микробиоты у мышей С57bl/6 в модели экспериментального туберкулеза

The objective: to study the changes in the lung microbiota in inbred C57BL/6 mice after aerogenic infection with M. tuberculosis in an experimental tuberculosis model.Subjects and Methods. This study was carried out on 20 female mice of inbred line C57BL/6 weighing 20-22 grams which were infected in a Glas-Col aerosol chamber (USA) with the culture of M. tuberculosis of virulent strain H37Rv at the dose of 400 CFU/lung. Morphological and microbiological assessment of the lungs state was performed before (day 0) (n=5) and 7 (n=5), 30 (n=5) and 60 (n=5) days after the infection. The results obtained were subjected to statistical processing using ANOVA test and Student t-test.Results. 7, 30, and 60 days after aerosol infection with M. tuberculosis against the background of successive morphological and microbiological changes typical of the experimental tuberculosis model, we established an imbalance of bacterial population in the lung microbiota. Before infection with M. tuberculosis, a scanty biotope was recorded with a predominance of lactobacilli –Lactobacillus murinus, Lactobacillus apodeme. 7, 30 and 60 days after infection with M. tuberculosis, consistent changes were recorded, such as increase in the number and diversity of the bacterial population. The most indicative markers of the recorded imbalance were: Streptococcus thoraltensis, Streptococcus acidominiminus, Arthrobacter crystallopoietes, Staphylococcus hominis, Micrococcus luteus.Conclusion. Tuberculosis infection is a significant factor affecting the state of the lung microbiota. With increased duration of the infection with M. tuberculosis, imbalance of the bacterial flora is formed in the lungs of C57BL/6 mice, accompanied by characteristic tissue inflammation and growing mycobacterial load.Цель исследования: изучить динамику изменений в микробиоте легких у инбредных мышей C57BL/6 после аэрогенного инфицирования M. tuberculosis в модели экспериментального туберкулеза.Материалы и методы. Настоящая работа выполнена на 20 самках мышей инбредной линии C57BL/6, массой 20–22 грамм, которые были заражены в аэрозольной камере Glas-Col (США) культурой Мtb вирулентного штамма H37Rv в дозе 400 КОЕ/легкое. Морфологическую и микробиологическую оценку состояния легких проводили до (день 0) (n=5) и через 7 (n=5), 30 (n=5) и 60 (n=5) дней после инфицирования. Полученные результаты подвергали статистической обработке с использованием теста ANOVA и Стьюдент t-теста.Результаты. Через 7, 30 и 60 дней после аэрозольного инфицирования M. tuberculosis, на фоне последовательных морфологических и микробиологических изменений, характерных для модели экспериментального туберкулеза, нами установлен дисбаланс бактериальной флоры в микробиоте легких. До заражения Mtb регистрировали скудный биотоп с преобладанием лактобацилл – Lactobacillus murinus, Lactobacillus apodeme. Через 7, 30 и 60 дней после инфицирования Mtb регистрировали последовательные изменения в виде увеличения количества и разнообразия бактериального сообщества. Наиболее показательными маркерами регистрируемого дисбаланса были: Streptococcus thoraltensis, Streptococcus acidominiminus, Arthrobacter crystallopoietes, Staphylococcus hominis, Micrococcus luteus.Заключение. Туберкулезная инфекция является значимым фактором, воздействующим на состояние микробиоты легких.С увеличением длительности инфицирования Mtb в легких мышей C57BL/6 формируется дисбаланс бактериальной флоры, сопровождающийся характерным тканевым воспалением и нарастанием микобактериальной нагрузки

Comparative study of the fatty acid composition of some groups of purple nonsulfur bacteria

The fatty acid composition (FAC) of 43 strains of purple nonsulfur bacteria belonging to six genera—Rubrivivax, Rhodopseudomonas, Rhodoplanes, Blastochloris, Rhodobium, and Rhodomicrobium—was studied by capillary gas chromatography. The cultures were grown on standard medium under standard conditions. Automatic identification of the fatty acid methyl esters and statistical processing of the results were performed by the computerized Microbial Identification System (MIS). Significant differences between the FACs of different genera, species, and, sometimes, strains were revealed. 16S rRNA genes of some of the new isolates, primarily those having a specific FAC, were sequenced. The taxonomic status of a number of the strains in question was determined using the FAC characteristics as one of the criteria. It was shown that the FAC characteristics may be used both for affiliating isolates to known species and for revealing new taxa

Taxonomic analysis of a group of strains of bacteriochlorophyll b-containing purple bacteria of the genus Blastochloris

The phylogenetic and phenotypic structure of a group of bacteriochlorophyll b-containing purple bacteria of the genus Blastochloris was studied to determine the taxonomic status of these bacteria. The group included the type strains of B. viridis and B. sulfoviridis and eight Blastochloris strains isolated from different water bodies. By DNA-DNA hybridization carried out by the optical method, three phylogenetic clusters were identified within the group studied the corresponded to three genospecies related at a DNA homology level of 30-50%. Two of these genospecies were represented by the type strains of B. viridis and B. sulfoviridis and by three new isolates each; the third genospecies included two new isolates, KR-70sv and KR-101sv. Comparative analysis of the fatty acid composition of four strains gave the same clusters as those yielded by DNA hybridization. Morphological and physiological investigation confirmed that strains phylogenetically close to B. viridis and B. sulfoviridis indeed belonged to these species. However, strains KR-70sv and KR-101sv, constituting a separate genospecies, showed no significant phenotypic distinctions from B. sulfoviridis and were assigned to this species. Thus, out of eight new isolates, three were referred to B. viridis and five to B. sulfoviridis. The latter strains are phenotypically similar but phylogenetically divergent

Experimental modeling of bacterially-induced Ca carbonate precipitation: new insights on possible mechanisms.

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The Family Rhodobacteraceae

The family Rhodobacteraceae can be considered a paradigm of modern taxonomy of prokaryotes. Taking into account the number of species and genera that conforms the family, together with the knowledge about their abundance and vast global distribution, it surprises that most of them have been described relatively recent to our days. Two notable exceptions are Rhodonostoc capsulatum (Molisch, Die purpurbakterien nach neuen untersuchungen, vols i–vii. G. Fischer, Jena, pp 1–95, 1907) and Micrococcus denitrificans Beijerinck and Minkman (Zentbl Bakteriol, Parasitenkd, Infektionskr Hyg. Abt II 25:30–63, 1910), early basonyms of Rhodobacter capsulatus and Paracoccus denitrificans, respectively. The fact that so many descriptions within this family are recent means that some studies have been concomitant and pose a challenge not only for pure taxonomic studies but also for interpreting other studies in which a rapidly evolving nomenclature had to be used anyway. The metabolic and ecological diversity of the group adds further complexity. In spite of all these difficulties, the picture is far from being a chaos and it can be considered an exciting and important bacterial group to study. Rhodobacteraceae are, fundamentally, aquatic bacteria that frequently thrive in marine environments. They comprise mainly aerobic photo- and chemoheterotrophs but also purple non-sulfur bacteria which perform photosynthesis in anaerobic environments. They are deeply involved in sulfur and carbon biogeochemical cycling and symbiosis with aquatic micro- and macroorganisms. One hundred genera are currently recognized as members of the family although the Stappia group, Ahrensia, Agaricicola, and Rhodothalassium do not belong, phylogenetically, to the family. The 90 other genera are distributed in 5 phylogenetic groups (the Rhodobacter, the Paracoccus, the Rhodovulum, the Amaricoccus, and the Roseobacter clades) that might be considered a family on its own