FEMS microbiology reviews最新文献

In the innovative field of engineered living materials (ELMs) microbiology and material sciences meet. These materials incorporate living organisms, such as bacteria, fungi, plants, or algae, to enable unique functions like self-assembly, actuation, and dynamic interaction. By utilizing (micro)biological systems in material design, ELMs promise to transform industries including healthcare, construction, and agriculture. In the early phase of ELM technology development, researchers implemented a single living strain in an already established user material. However, the complexity and potential of these materials is limited by the abilities of this single strain. Even though synthetic biology brings the opportunity to add a range of nonnative bioactivities to these cells and thus the material, the increasing metabolic burden upon implementation of multiple nonnative pathways limits the capacity of a single strain. Furthermore, higher organisms and nonstandard hosts are often desired in material settings for their native physical or metabolic advantages. However these are not always straightforward to further engineer. Thus, the use of multiple, specialized strains broadens the functionalities and thus the applicability of ELMs. Multistrain ELMs are a brand-new technology, with many promising applications.

The exquisite ability of bacteria to adapt to their environment is essential for their capacity to colonize hostile niches. In the cystic fibrosis (CF) lung, hypoxia is among several environmental stresses that opportunistic pathogens must overcome to persist and chronically colonize. Although the role of hypoxia in the host has been widely reviewed, the impact of hypoxia on bacterial pathogens has not yet been studied extensively. This review considers the bacterial oxygen-sensing mechanisms in three species that effectively colonize the lungs of people with CF, namely Pseudomonas aeruginosa, Burkholderia cepacia complex, and Mycobacterium abscessus and draws parallels between their three proposed oxygen-sensing two-component systems: BfiSR, FixLJ, and DosRS, respectively. Moreover, each species expresses regulons that respond to hypoxia: Anr, Lxa, and DosR, and encode multiple proteins that share similar homologies and function. Many adaptations that these pathogens undergo during chronic infection, including antibiotic resistance, protease expression, or changes in motility, have parallels in the responses of the respective species to hypoxia. It is likely that exposure to hypoxia in their environmental habitats predispose these pathogens to colonization of hypoxic niches, arming them with mechanisms than enable their evasion of the immune system and establish chronic infections. Overcoming hypoxia presents a new target for therapeutic options against chronic lung infections.

Microbial manufacturing offers a sustainable and environmentally friendly approach for chemical production. However, the inherent toxicity of certain high-value chemicals to microbial cell factories presents a significant challenge, severely constraining production efficiency. To enhance microbial tolerance, extensive synthetic biology strategies have been developed. The cell envelope serves as the primary natural barrier in microorganisms, and both its intrinsic composition, including membrane lipids, membrane proteins, and cell wall components, and the regulation of these components play crucial roles in modulating cellular responses to environmental stress. Engineering strategies targeting intracellular components, such as transcription factors and repair pathways, have demonstrated effectiveness in enhancing microbial tolerance to toxic end-products and intermediates. Additionally, recent advances have focused on extracellular engineering, including biofilm formation and the modulation of intercellular interactions, which have garnered significant scientific interest. This review aims to provide a systematic overview of these strategies and offers insights to facilitate the industrial translation and commercialization of microbial production of toxic end-products and intermediates.

Following over a century's worth of research, our understanding of Pneumocystis has significantly expanded in various facets, spanning from its fundamental biology to its impacts on animal and human health. Its significance in public health has been underscored by its inclusion in the 2022 WHO fungal priority pathogens list. We present this review to summarize pivotal advancements in Pneumocystis epidemiology, host specificity, genetic diversity and evolution. Following a concise discussion of Pneumocystis species classification and divergence at the species and strain levels, we devoted the main focus to the following aspects: the epidemiological characteristics of Pneumocystis across nearly 260 mammal species, the increasing recognition of coinfection involving multiple Pneumocystis species in the same host species, the diminishing host specificity of Pneumocystis among closely related host species, and the intriguingly discordant evolution of certain Pneumocystis species with their host species. A comprehensive understanding of host specificity, genetic diversity, and evolution of Pneumocystis can provide important insights into pathogenic mechanisms and transmission modes. This, in turn, holds the potential to facilitate the development of innovative strategies for the prevention and control of Pneumocystis infection.

Bacteria require sophisticated sensing mechanisms to adjust their metabolism in response to stressful conditions and survive in hostile environments. Among them, toxin-antitoxin (TA) systems play a crucial role in bacterial adaptation to environmental challenges. TA systems are considered as stress-responsive elements, consisting of both toxin and antitoxin genes, typically organized in operons or encoded on complementary DNA strands. A decrease in the antitoxin-toxin ratio, often triggered by specific stress conditions, leads to toxin excess, disrupting essential cellular processes and inhibiting bacterial growth. These systems are categorized into eight types based on the nature of the antitoxin (RNA or protein) and the mode of action of toxin inhibition. While the well-established biological roles of TA systems include phage inhibition and the maintenance of genetic elements, the environmental cues regulating their expression remain insufficiently documented. In this review, we highlight the diversity and complexity of the environmental cues influencing TA systems expression. A comprehensive understanding of how these genetic modules are regulated could provide deeper insights into their functions and support the development of innovative antimicrobial strategies.

Bacteria can cooperate by coordinating their gene expression through the production, release, and detection of small molecules, a phenomenon known as quorum sensing (QS). One type of QS commonly found in Gram-negative bacteria utilizes a LuxI-type enzyme to produce a signaling molecule of the N-acyl-homoserine lactone (AHL) family, and a transcription factor of the LuxR family to detect and respond to the AHL. In a subset of Enterobacteriaceae, including Escherichia coli and Salmonella, no LuxI family member is present and no AHLs are synthesized. However, they encode a LuxR family member, SdiA, that is used to detect the QS molecules of other bacterial species, a behavior known as eavesdropping. Despite significant research on the topic, the overall role of SdiA-mediated eavesdropping in these bacteria remains unclear. In this review, we discuss the phenotypes and regulons of SdiA in the Enterobacteriaceae.

Candida albicans is a fungus that colonizes the gut, oral, and vaginal mucosae of most humans without causing disease. However, under certain predisposing conditions this fungus can cause disease. Candida albicans has several factors and attributes that facilitate its commensal and pathogenic lifestyles including the transition from a yeast to a hyphal morphology, which is accompanied by the expression of virulence factors. These factors are central in candidiasis that can range from invasive to superficial. This review focuses on one example of a superficial disease, i.e. vulvovaginal candidiasis (VVC) that affects ~75% of women at least once with some experiencing four or more symptomatic infections per year (RVVC). During VVC, fungal factors trigger inflammation, which is maintained by a dysregulated innate immune response. This in turn leads to immunopathology and symptoms. Another unique characteristic of the vaginal niche, is its Lactobacillus-dominated microbiota with low species diversity that is believed to antagonize C. albicans pathogenicity. The importance of the interactions between C. albicans, the host, and vaginal microbiota during commensalism and (R)VVC is discussed in this review, which also addresses the application of this knowledge to identify novel treatment strategies and to study vaginal C. albicans infections.

Biodegradation plays a pivotal role in controlling environmental pollution. Naturally occurring microbes can degrade various environmental pollutants; however, the bioremediation of emerging pollutants resulting from the synthesis of recalcitrant organic compounds has not been sufficiently studied. These compounds pose significant environmental risks when released into soil and water bodies. Therefore, it is essential to accelerate the acquisition of knowledge on their biodegradation and foster the development of advanced bioremediation strategies. Recent progress in sequencing technologies and high-precision analytical instruments, coupled with ever-increasing computing power, has revolutionized conventional biodegradation research. In this review, the fundamental principles and commonly used techniques in bacteria-mediated biodegradation were discussed, emphasizing an integrated approach for a comprehensive understanding of the biodegradation process. This review provides in-depth insights into the current progress and prospects of biodegradation research.