Volume 61 (2022): Edizione 4 (December 2022)

Bdellovibrio bacteriovorus is a predatory gram-negative delta-proteobacteria that preys on other gram-negative bacterial species. With the surge in the cases of Anti-Microbial Resistance and the demand to replace conventional antibiotics, this predatory attribute of B. bacteriovorus has led to a vast number of studies in the last decade alone. These studies demonstrated various aspects of predation and proposed using B. bacteriovorus as an alternative new approach to conventional antibiotics in humans. Here we review the current progress made in this promising new area of research to develop novel antibacterial approaches.

Minerals have been important throughout history, but nowadays, their use has increased, as well as their extraction needs. Therefore, due to the growing demand for metals, and both the depletion of high-grade ores and their related environmental concerns, the mining industry has been forced to leave behind the past traditional techniques of metal recovery (use of inorganic acids), and adopt eco-friendlier alternatives, such as the utilization of weaker leaching agents, such as organic acids. Thus, the present review is focused on the use of microbially-produced organic acids as a promising alternative to conventional techniques in the mining industry, with emphasis on the following topics: a) the advantages and disadvantages of the use of organic acids for leaching purposes, b) the main microorganisms studied for the production of these organic acids, c) a summary of the latest reports on bioleaching as well as a comparison of the existent techniques; d) the explanation of leaching mechanisms where organic acids may be involved, to fulfill metal recovery; and, e) interactions between metallic ions and organic acids. The review of the current knowledge regarding the use of organic acids for leaching purposes seeks the visualization of relevant strategies that may be improved for metal-recovery processes, intending to develop circular economy practices that may have the potential to be implemented at an industrial scale.

This year we are celebrating the 200th anniversary of the birth of Louis Pasteur, one of the fathers of microbiology. Interestingly, the time when Pasteur disproved the doctrine of „spontaneous generation” and announced the “germ theory of disease” coincides with the discovery of Cryptococcus neoformans and its role in cryptococcosis. Today, only in the realm of guesswork can remain the correct answer to the question „whether the observed parallelism of these events was accidental?” or „whether Pasteur’s discoveries constituted a solid foundation of the research on the etiological factors of cryptococcosis?”. Until recently, it might seem that all major virulence factors of pathogenic fungi of the Cryptococcus species complex have been thoroughly described. Meanwhile, the simultaneous publication in 2018 of three in vitro protocols for the induction of Titan cells, also known as giant cells, opened up new possibilities for research on the relatively uncharacterized virulence factor that is crucial for Cryptococcus spp. Research on the titanization process makes us realize how little we know about the virulence factors of these fungi, and how much more can be improved in the context of the treatment and prevention of cryptococcosis. The following review is not only a historical outline of research on Cryptococcus spp. and cryptococcosis, but also synthetically describes the virulence factors of these basidiomycetous yeasts, with particular emphasis on the titanization process. The phenomenon of titanization as a process of a specific morphological transformation, like Titan cells, are completely new terms in Polish literature, which will be introduced to readers here. We live in a post-antibiotic era where the lack of effective and non-toxic drugs affects patients all over the world. Specifically, the availability of only fluconazole, amphotericin B and flucytosine in therapy of cryptococcosis constitutes a significant limitation. For this reason, research on the virulence factors of Cryptococcus spp. will allow to find new effective antimycotics, including inhibitors of the titanization process.