Bacteria, Volume 3, Issue 3 (September 2024) – 10 articles

For years, the Bacillus genus has encompassed a heterogeneous group of individuals whose main common trait was their ability to sporulate in the presence of oxygen. This criterion has been revised, resulting in the reclassification of several species into new genera and to a redefinition of the characteristics of the members of this taxon. Currently, the species of the genus are grouped into the Subtilis clade and the Cereus clade. The former, called Bacillus sensu stricto, initially composed of B. subtilis, B. licheniformis, B. pumilus, and B. amyloliquefaciens, has subsequently incorporated new species related to these. The Cereus clade, Bacillus cereus sensu lato, consists of pathogenic species (B. anthracis, B. cereus, and B. thuringiensis) as well as others of significance in agriculture and industry. Furthermore, identifying these individuals remains complex, requiring alternatives to 16S rRNA sequencing. The ability to form spores resistant to stressful conditions provides a significant advantage over other genera, with observable differences in sporulation rates and spore structure among different species. Additionally, Bacillus spp. are known for their capacity to produce antimicrobial substances, lytic enzymes, and volatile organic compounds, each with diverse applications. Some species are even used as probiotics. This review delves into aspects related to the taxonomy and identification of microorganisms belonging to the genus Bacillus, which often present challenges. The aim is to provide a comprehensive overview of the topic. In addition, it highlights the characteristics and applications of the genus, emphasizing its importance in biotechnology and microbiology. Full article

The Lactobacillales (LB) stand apart among bacterial orders, using manganese (Mn) instead of iron to support their growth and swiftly ferment complex foods while acidifying their environment. The present work investigates whether a shift in the use of Mn could mark the origin of LB. Transmembrane carriers of the ubiquitous Slc11 family play key roles in LB physiology by catalyzing proton-dependent Mn import. In prior studies, the Slc11 clade found in LB (MntH Cb, MCb) showed both remarkable structural plasticity and highly efficient Mn uptake, and another Slc11 clade, MCg1, demonstrated divergent evolution coinciding with emergence of bacterial genera (e.g., Bordetella, Achromobacter). Herein, the Slc11 clade MCb is subdivided in sister groups: MCb_ie and MCb_gut. MCb_ie derives directly from the Slc11 clade MCa, pointing an intermediate stage in the evolution of MCb_gut. MCb_ie predominates in marine Bacillaceae, is more conserved than MCb_gut, lacks the structural plasticity that typify MCb_gut carriers, and responds differently to identical mutagenesis. Exchanging MCb_ie/MCb_gut amino acid residues at sites that distinguish these clades showed conformation-dependent effects with both MCb_ie and MCb_gut templates, and the 3D location of the targeted sites in the carrier structure together suggests that the mechanism to open the inner gate, and release Mn into the cytoplasm, differs between MCb_ie and MCb_gut. Building on the established phylogeny for Enterococcus revealed that a pair of genes encoding MCb_gut was present in the common ancestor of LB, as MCb_gu1 and MCb_gu2 templates exhibited distinct structural dynamics properties. These data are discussed when examining whether MCb_gut⁺ LB could emerge in the upper gut of early vertebrates (ca. 540 mya), through genome contraction and evolution toward Mn-centrism, as they specialized as gastric aids favoring stomach establishment in jawed vertebrates through bi-directional communication with host nervous, endocrine and immune systems. Full article

Oral health remains one of the most taken for granted parts of human body health, even though poor oral health has now been linked to various diseases, such as cancers, diabetes, autoimmune complications, neurological disorders, and cardiovascular disease, just to name a few. As we review in this paper, substance use or abuse, including alcohol, smoking, recreational drugs, and pharmaceutical drugs can have significant implications on oral health, which in turn can lead to more systemic diseases. In this paper, we show that oral microbiome dysbiosis and inflammatory cytokine pathways are two of the most significant mechanisms contributing to oral health complications from substance use. When substance use decreases beneficial oral species and increases periodontopathogenic strains, a subsequent cascade of oncogenic and inflammatory cytokines is triggered. In this review, we explore these mechanisms and others to determine the consequences of substance use on oral health. The findings are of significance clinically and in research fields as the substance-use-induced deterioration of oral health significantly reduces quality of life and daily functions. Overall, the studies in this review may provide valuable information for future personalized medicine and safer alternatives to legal and pharmaceutical substances. Furthermore, they can lead towards better rehabilitation or preventative initiatives and policies, as it is critical for healthcare and addiction aid specialists to have proper tools at their disposal. Full article

According to the World Health Organization (WHO), tuberculosis (TB) remains a significant global health challenge, with approximately 10 million new cases and 1.4 million deaths reported in 2020. TB disproportionately affects low- and middle-income countries, where factors such as migrant population, malnutrition, type 2 diabetes, human immunodeficiency virus (HIV) co-infection, and COVID-19 exacerbate its impact. TB also leads to substantial economic losses due to decreased productivity and high healthcare costs. Despite advances in treatments, TB remains a major public health issue, particularly in poorer regions. In Mexico, TB is considered a moderate-incidence disease, with higher prevalence in border states, mainly due to population displacements. Effective TB control requires collaboration between Mexico and the United States of America given the high cross-border human movement, like in the Baja California State that reported predominantly pulmonary TB cases. Effective management of TB involves rapid diagnosis and identification of antibiotic resistance. Techniques such as PCR, high-resolution computed tomography (HRCT), and/or Xpert MTB/RIF have enhanced diagnostic accuracy. Future perspectives about TB management focus on developing new drugs and vaccines to combat drug-resistant strains, and the comorbidities associated, which must be addressed to reinforce of health public programs. Full article

This paper explores the intriguing parallels between bacterial behavior and human actions, specifically the tendency of bacteria to adhere to surfaces, construct bacterial “houses” known as a biofilm matrix, nurture growth and reproduction within the biofilm matrix, and disperse upon maturity. Termed as the bacterial “houses”, biofilm matrices exert significant influence on various aspects of human life. A well-structured biofilm matrix serves as the foundation for establishing biofilm reactors capable of efficiently removing heavy metal pollutants from water. Conversely, a dysfunctional biofilm matrix can lead to infections and subsequent illnesses in the human body. Therefore, the study of the biofilm matrix emerges as pivotal. Employing a bibliographic study methodology, this paper analyzes 1000 web of science articles in the field, investigating key keywords, influential countries/regions, organizations, and their interconnections. The findings illuminate the primary themes in biofilm matrix research and offer insights into future directions for this critical field of study. Full article

Antimicrobial resistance is a significant public health issue. The unprecedented spread of antimicrobial-resistant organisms has been identified by the World Health Organization as one of the leading healthcare threats. Projections for annual worldwide deaths attributed to antimicrobial resistance approach 10 million by 2050, with an associated economic burden of USD 100 trillion. This paper reviews the mechanisms known to contribute to antimicrobial resistance and provides insight into potential available alternatives to conventional antibiotics. Antimicrobial approaches addressed include dual antibiotic therapy, antimicrobial peptides, monoclonal antibodies, bacteriophages, probiotics, nanomaterials, and cannabinoids. Key pathogens in need of antimicrobials referred to as the ESKAPE pathogens are discussed. Full article

Background: Several Acinetobacter species live in different ecosystems, such as soil, freshwater, wastewater, and solid wastes, which has attracted considerable research interests in public health and agriculture. Methods: We assessed the distribution of Acinetobacter baumannii and Acinetobacter nosocomialis in three freshwater resources (Great Fish, Keiskemma, and Tyhume rivers) in South Africa between April 2017–March 2018. Molecular identification of Acinetobacter species was performed using Acinetobacter-specific primers targeting the recA gene, whilst confirmed species were further delineated into A. baumannii and A. nosocomialis. Similarly, virulence genes; afa/draBC, epsA, fimH, OmpA, PAI, sfa/focDE, and traT in the two Acinetobacter species were assessed. Results: Our finding revealed that 410 (48.58%) and 23 (2.7%) of the isolates were confirmed as A. baumannii and A. nosocomalis, respectively. Additionally, three hundred and eight (75.12%) A. baumannii and three (13.04%) A. nosocomialis exhibited one or more of the virulence genes among the seven tested. OmpA was the most prevalent virulence gene in A. baumannii in freshwater sources. Conclusions: The distribution of clinically important Acinetobacter species in the freshwater sources studied suggests possible contamination such as the release of hospital wastewater and other clinical wastes into the environment thereby posing a risk to public health. Full article

It is imperative to say that we are immersed in a sea of microorganisms due to their ubiquitous presence on the planet, from soil to water and air. Human bodies harbor a vast array of microorganisms from both the inside and out called the human microbiome. It is composed of single-celled organisms, including archaea, fungi, viruses, and bacteria, including bacteriophages, where bacteria are the biggest players, and this is collectively referred to as the human microbiome. These organisms have a symbiotic relationship with humans and impact human physiology where they colonize various sites on and in the human body, adapting to specific features of each niche. However, dysbiosis, or the deviation from normal microbial composition, is associated with adverse health effects, disrupted ecosystems, and eco-imbalance in nature. In this review, we delve into the comprehensive oversight of bacteria, their cosmopolitan presence, and their additional applications affecting human lives. Full article

Biofilms are accumulations of microorganisms in an extracellular polymeric substance matrix which are composed of polysaccharides, proteins, lipids, and nucleic acids. Many bacteria can switch between a planktonic form and a biofilm form. The planktonic bacteria have relatively high cell growth and reproduction rates and have a reduced likelihood of survival but can adapt to occupy new habitats. The biofilm state appears to be a natural and predominant state of bacteria. The need for the formation of bacterial biofilm is that it enhances the tolerance of bacteria to harsh environmental conditions, thereby allowing bacteria to avoid being washed away by water flow or the bloodstream by simply attaching to a surface or tissue, and the EPS matrix protects bacteria cells, in deeper layers, against antimicrobial agents, probably by limiting the diffusion of these agents. Biofilm formation steps are initial contact/attachment to the surface, followed by micro-colony formation, maturation and formation of the architecture of the biofilm, and finally detachment/dispersion of the biofilm. Once formed, biofilm restricts bacterial mobility and increases cell density. Secretions of autoinducers into the environment are critical for cross-signaling between bacteria. This cross-talk is called quorum sensing (QS). Quorum sensing is a cell–cell communication mechanism between bacteria that allows specific processes to be controlled, such as biofilm formation and virulence factor expression. Bacterial quorum sensing signaling mainly consists of acyl-homoserine lactones (produced by Gram-negatives), autoinducing peptides (produced by Gram-positives), and autoinducer-2 (produced by both Gram-negatives and Gram-positives). Therefore, this review is aimed at how bacterial biofilms work and are formed. Full article