The fascinating world of lichens draws the attention of the researchers because of the numerous properties of lichens used traditionally and, in modern times, as a raw material for medicines and in the perfumery industry, for food and spices, for fodder, as dyes, and for other various purposes all over the world. However, lichens being widespread symbiotic entities between fungi and photosynthetic partners may acquire toxic features due to either the fungi, algae, or cyano-procaryotes producing toxins. By this way, several common lichens acquire toxic features. In this survey, recent data about the ecology, phytogenetics, and biology of some lichens with respect to the associated toxin-producing cyanoprokaryotes in different habitats around the world are discussed. Special attention is paid to the common toxins, called microcystin and nodularin, produced mainly by the Nostoc species. The effective application of a series of modern research methods to approach the issue of lichen toxicity as contributed by the cyanophotobiont partner is emphasized.

Cyanoprokaryotes are distributed worldwide and they produce various bioactive compounds, including cyanotoxins. The major route of human exposure to cyanotoxins is the oral intake by using contaminated drinking water, by incidental intake of contaminated water during recreational and professional activities, and by consuming contaminated food or dietary supplements prepared from cyanobacteria. The prolonged chronic exposure to low concentrations of cyanotoxins provokes cell damage and may increase the risk for cancer development. Due to the variety of cyanotoxin chemical structures, different mechanisms of their toxic effects are known. At the same time, some of the natural compounds produced by cyanoprokaryotes have anticancer potential and are promising sources for the development of novel drugs. This chapter is dedicated to the target mechanisms behind the effects of the widely distributed cyanotoxins with an impact on human health, microcystins, nodularins, and cylindrospermopsin.

This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: red algae Lemanea rigida and Paralemanea torulosa, mycorrhizal fungi Amanita simulans and Terfezia pseudoleptoderma, parasitic fungus Microbotryum vinosum, saprotrophic fungus Sarcoscypha jurana, stonewort Chara tenuispina, mosses Brachytheciastrum collinum and Meesia longiseta, monocots Dactylorhiza romana and Neotinea maculata and dicots Adenophora liliifolia, Ambrosia artemisiifolia and Tanacetum corymbosum subsp. cinereum are given within SE Europe and adjacent regions.

Coronavirus disease 2019 represents a serious challenge for modern society worldwide because of the considerable and unfavourable consequences of the pandemic in terms of human health, economics and social life. In the present concise survey, some essential peculiarities of ozone as disinfecting and therapeutic means under the conditions of COVID-19 pandemic as reflected in the recent literature are described. Particularttention is paid to modern hospital disinfection means and methods. Ozone exerts antiviral activity through the inhibition of viral replication and direct inactivation of viruses by interfering with the virus replication phase and attacking capsid proteins. Ozone therapy is very inexpensive and may safely exploit the critical vulnerability in COVID-19.