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Bifidobacteria are naturally occurring, health-promoting bacteria in the gastrointestinal tract (GIT). As they are saccharolytic organisms, their colonization of the GIT requires the ability to utilize the complex carbohydrates present in that niche. Egan et al. (p. 6611–6623) have demonstrated that a bifidobacterial strain, namely Bifidobacterium breve UCC2003, can metabolize N-acetylglucosamine-6-sulfate, a sulfated monosaccharide typically found in the mucin glycoprotein. The gene cluster associated with this trait is limited to members of the species B. breve. This discovery further highlights this species' ability to utilize mucin-derived monosaccharides, a highly advantageous trait in an extremely competitive environment.
The carriage of antibiotic resistance genes (ARGs) by mobile elements in bacteria is the major contributor to bacterial drug resistance. The evolutionary aspects of these mobile ARGs among different bacterial taxa and their behavior within human and animal gut microbiota have not been described. Hu et al. (p. 6672–6681) have analyzed the dissemination of mobile ARGs by horizontal gene transfer, using genomic data that include over 23,000 bacterial genomes and about 10 million human and animal gut genes. Apparently, the mobile ARGs are enriched in the phylum Proteobacteria and shared by pathogenic and nonpathogenic bacteria that can be traced to animal gut microbiota.
Bacillus anthracis, the bacterium that causes anthrax, is an important agent of concern. Nonpathogenic surrogates are essential to predict its dispersal and fate after a release. Bishop and Stapleton (p. 6682–6690) have developed a new surrogate (Btcry−) that is highly similar to that select agent. High levels of Btcry− and an established surrogate were released in aerosol form in an open-ended barn. It was found that, under the prevailing conditions, Btcry− remained airborne for a shorter distance than the old surrogate but had a sixfold-higher propensity to adhere to vertical surfaces. These findings have relevance to hazard assessment and decontamination measures.
Nosema ceranae is a microsporidian parasite that has been implicated in honey bee colony losses worldwide. RNA interference (RNAi) has emerged as a potent and specific strategy for controlling parasites and pathogens in honey bees. Li et al. (p. 6779–6787) employed the RNAi technique to silence a honey bee gene, naked cuticle (nkd), which is a negative regulator of host immune function. Their results indicate that silencing nkd can improve honey bee immune function and suppress the reproduction of N. ceranae. This represents a novel host-derived therapeutic for bee disease treatment.
Microbially influenced corrosion (MIC) is a recognized multibillion-dollar challenge to maritime infrastructure, but the process of microbial colonization of steel is not yet well understood. Mumford et al. (p. 6799–6807) describe the growth of a marine iron-oxidizing bacterium (FeOB), Mariprofundus sp. strain DIS-1, in a continuous culture system and the direct visualization of steel colonization under aerobic conditions by FeOB. Genomic analysis of strain DIS-1 revealed oxygen tolerance genes not found in other Mariprofundus strains. These observations suggest a role for FeOB in MIC and provide a useful model and new methods for studying interactions between microbes and solid substrates.