Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Evaluation of the Cell Growth of Mycobacteria Using Mycobacterium smegmatis mc2 155 as a Representative Species: Jorge A. Gonzalez-y-Merchand , Ruben Zaragoza-Contreras , Rosalina Guadarrama-Medina , Addy C. Helguera-Repetto , Sandra Rivera-Gutierrez , Jorge F. Cerna-Cortes , Leopoldo Santos-Argumedo , Robert A. Cox; J. Microbiol. 2012;50(3):419-425. Published online June 30, 2012; DOI: https://doi.org/10.1007/s12275-012-1556-0

Abstract: The study of the in vitro cell growth of mycobacteria still remains a fastidious, difficult, and time-consuming procedure. In addition, assessing mycobacterial growth in the laboratory is often complicated by cell aggregation and slow growth-rate. We now report that the use of a stainless steel spring in the culture led to an absence of large cell clumps, to a decrease of dead cells in the exponential phase and to growth of a more homogeneous population of large cells. We also report that flow cytometry is a rapid, simple and reliable approach to monitor mycobacterial cell growth and viability. Here, we monitored Mycobacterium smegmatis cellular growth by optical density, dry cell mass, and colony forming units; in addition, viability, cell size and granularity profiles were analyzed by flow cytometry, and cell morphology by electron microscopy. Cultures monitored by flow cytometry may lead to a better understanding of the physiology of mycobacteria. Moreover, this methodology may aid in characterizing the cell growth of other fastidious species of microorganisms.

Complete Genome of Leptospirillum ferriphilum ML-04 Provides Insight into Its Physiology and Environmental Adaptation: Shuang Mi , Jian Song , Jianqun Lin , Yuanyuan Che , Huajun Zheng , Jianqiang Lin; J. Microbiol. 2011;49(6):890-901. Published online December 28, 2011; DOI: https://doi.org/10.1007/s12275-011-1099-9

Abstract: Leptospirillum ferriphilum has been identified as the dominant, moderately thermophilic, bioleaching microorganism in bioleaching processes. It is an acidic and chemolithoautrophic bacterium that gains electrons from ferrous iron oxidation for energy production and cell growth. Genetic information about this microorganism has been limited until now, which has hindered its further exploration. In this study, the complete genome of L. ferripilum ML-04 is sequenced and annotated. The bacterium has a single circular chromosome of 2,406,157 bp containing 2,471 coding sequences (CDS), 2 rRNA operons, 48 tRNA genes, a large number of mobile genetic elements and 2 genomic islands. In silico analysis shows L. ferriphilum ML-04 fixes carbon through a reductive citric acid (rTCA) cycle, and obtains nitrogen through ammonium assimilation. The genes related to “cell envelope biogenesis, outer membrane” (6.9%) and “DNA replication, recombination and repair” (5.6%) are abundant, and a large number of genes related to heavy metal detoxification, oxidative and acidic stress defense, and signal transduction pathways were detected. The genomic plasticity, plentiful cell envelope components, inorganic element metabolic abilities and stress response mechanisms found the base for this organism’s survival in the bioleaching niche.

Search