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Bacteroides
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
The genus Bacteroides has undergone major taxonomic revisions in the past few years, and most species suffer changes frequently. Suitable taxonomic changes have become important to clinicians and microbiologists, since these changes can be used as an indicator of virulence or antimicrobial resistance. It is known that some species of the Bacteroides genus, such as B. thetaiotaomicron, are much more resistant to antimicrobials than B. fragilis, for example. In 1990, various species were moved to other genera, including Porphyromonas and Prevotella, and others were included, such as Dialister, Megamonas, Mitsuokella, Tannerella, Tissierella, and Alistipes. By using culture-independent techniques such as 16S rRNA gene sequencing, a number of new species have been added to the genus Bacteroides, achieving more than 20 bacterial species.2,3 In 2005, new species added to this genus included Bacteroides goldsteinii, Bacteroides nordii, and Bacteroides salyersai, Bacteroides plebeius and Bacteroides coprocola (isolated from human feces), and Bacteroides massiliensis (isolated from the blood of a newborn). Subsequently, B. goldsteinii, Bacteroides distasonis, and Bacteroides merdae were moved to the genus Parabacteroides.4 The occurrence of species of the B. fragilis group in the fecal microbiota of children with diarrhea is shown in Table 16.2.
Imaging the in vivo growth patterns of bacteria in human gut Microbiota
Published in Gut Microbes, 2021
Liyuan Lin, Jia Song, Jian Li, Xiaolei Zuo, Hong Wei, Chaoyong Yang, Wei Wang
Out of the 42 FISH labeling tested, we were able to identify 32 species with high selectivity, covering bacteria from nine families, with half-stained Gram-negative (Figure 2) and the other half stained Gram-positive bacteria (Figure 3). Gram-negative bacteria that belonged to the family Bacteroidaceae and Porphyromonadaceae were 1–2 μm rods, and showed relatively weak FDAA labeling due to their thinner PGN (Figure 2(a–j)). Some Gram-negative bacteria belonging to the Clostridium (Figure 2k-m) and Megamonas (Figure 2(n–p)) genus of the phylum Firmicutes, however, showed comparable FDAA labeling intensities with many Gram-positive bacteria. This leads to the speculation that these bacteria may possess Gram-positive-like PGN structures, even though they are normally stained as Gram-negative.13,14 The labeling patterns of the species belonging to the Clostridium genus (Figure 2(k–m)) were relatively similar, which divided in binary fission with a red septum in the middle of the bacteria. Megamonas (Figure 2(n–p)) bacteria were large rods with rounded ends, and the presence of volutin granules15 could be found in some species (Figure 2n). Furthermore, the labeling signals from the two FDAA probes were highly overlapped in these three species, indicative of their highly active growth and metabolism during the labeling process.
Vitamin D supplementation in pregnancy and early infancy in relation to gut microbiota composition and C. difficile colonization: implications for viral respiratory infections
Published in Gut Microbes, 2020
Kelsea M. Drall, Catherine J. Field, Andrea M. Haqq, Russell J. de Souza, Hein M. Tun, Nadia P. Morales-Lizcano, Theodore B. Konya, David S. Guttman, Meghan B. Azad, Allan B. Becker, Diana L. Lefebvre, Piush J. Mandhane, Theo J. Moraes, Malcolm R. Sears, Stuart E. Turvey, Padmaja Subbarao, James A. Scott, Anita L Kozyrskyj
However, we found direct vitamin D supplementation of infants to be associated with a lower abundance of Megamonas in gut microbiota. This association was found in all study infants and was independent of feeding mode. While little is known about Megamonas in infancy, this genus was enriched in the gut microbiota of male infants born to mothers with prenatal asthma in a previous publication from the CHILD cohort.22 In addition to childhood asthma, maternal history of asthma is a risk factor for greater severity of viral bronchiolitis in offspring.23Megamonas has recently been reported to be more abundant in the gut microbiota of adult males with higher testosterone levels24 and the role of this sex steroid is currently being scrutinized in asthma pathogenesis.25 In view of reported benefits of the vitamin D supplementation of high risk mothers and of infant populations where supplementation is not the norm,7,11 the Megamonas genus of Veillonellaceae may be a possible link between vitamin D and asthma or viral respiratory infection that merits further examination. It would also further support recommendations for the supplementation of formula-fed infants. Vitamin D plays a crucial role in both innate immunity, via toll-like receptor signaling of macrophages in response to pathogens, and adaptive immunity, by inhibiting proliferation of T cells and secretion of inflammatory cytokines.13,26 Further, there is emerging evidence for its role in the lung microbiome and gut-lung axis.27
Dysbiosis in a canine model of human fistulizing Crohn’s disease
Published in Gut Microbes, 2020
Ana Maldonado-Contreras, Lluís Ferrer, Caitlin Cawley, Sarah Crain, Shakti Bhattarai, Juan Toscano, Doyle V. Ward, Andrew Hoffman
Megamonas is a common gut commensal microbe of carnivore animals. Increased abundance of Megamonas has been found in healthy cats61 and in dogs consuming inulin-rich diets.62 Few studies have shown the relevance of Megamonas in human health.63,64Megamonas species are important propionate and acetate producers.65,66 Thus, based on these results, a greater emphasis on Megamonas, and its potential impact on gastrointestinal health, may be justified in the future.