China
Africa
Explore chapters and articles related to this topic
Streptomyces: A Potential Source of Natural Antimicrobial Drug Leads
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Mahmoud A. Elfaky, Hanaa Nasr, Ilham Touiss, Mohamed L. Ashour
Nonculturable microorganisms make up many microbial species and are thought to be a source of new secondary metabolites. The isolation chip (iChip), a system for extracting bacterial cultures in a natural environment, and co-cultivation of actinomycetes with other bacteria are two techniques that have been successfully used to enhance cultivation-based methods. The combination, as mentioned above, of iChip and unexplored environments or symbiotic relationships is also exciting (Manteca and Yagüe 2019).
Conventional culture methods with commercially available media unveil the presence of novel culturable bacteria
Published in Gut Microbes, 2019
Tamaki Ito, Tsuyoshi Sekizuka, Norimi Kishi, Akifumi Yamashita, Makoto Kuroda
A typical human intestine has around 1,000 bacterial species,1 and these ca. 38-trillion cells constitute the gut microbiota,2 showing that the number of bacteria is of the same order as the number of human cells (ca. 30-trillion cells). Recently, metagenomic analysis of bacterial 16S rRNA (ribosomal RNA) gene sequences targeted at the human gut microbiota using next generation sequencing (NGS) has resulted in detailed compositional information about the human gut microbiota, including uncultured bacterial species. Gordon et al. reported a correlation between obesity and the gut microbiota in 2006 and 2008;3,4 the gut microbiota has also been suggested to correlate not only with the maintenance of our health but also with bowel disease and systemic diseases including autoimmune disease and metabolic disease.5 Furthermore, recent studies have indicated that host genetics influence the composition of the human gut microbiome,6 while diet and environments appear to have a greater impact than host genetics,7 and a particular gut bacterial species has been notably correlated with other bacterial infections.8 Therefore, as well as human genetics, it becomes increasingly important to investigate the details of the gut microbiota. Because some intestinal bacteria are generally considered to be unculturable or minor population, such bacteria have not been well characterized yet, and are difficult to identify in the laboratory. To overcome this point, Nichols et al. designed an isolation chip (ichip) for high-throughput bacterial cultivation, consisting of several hundred miniature diffusion chambers, each inoculated with a single environmental cell.9 Bioinformatics researchers have succeeded in inferring the complete genome sequences of gut bacteria from metagenomic sequence data and thus gained insights, including metabolic profiles, into their ecological niches, nutrient requirements, and potential roles in maintaining our health.10 Thus, microbial culture techniques have been de-emphasized to date; however, there are limitations to the information that can be obtained from molecular approaches alone, and the pure culture of intestinal microbiota remains essential to define the roles of specific bacteria in the intestine. In addition, culture using selective media allows for the growth and detection of less abundant bacteria that may be missed by insufficient sequencing depth in culture-independent studies.11 Recently, several approaches have been established for the culture-based isolation of previously unculturable bacteria.