Aquae Calidae, Bulgaria Aquae Calidae, Bulgaria Aquae Calidae (Latin for warm waters), also known as Therma and Thermopolis in the Middle Ages, was an ancient town in Thrace located in the territory of today's Bulgarian port city of Burgas. It was built around thermal baths using the hot springs and became one of the most important spa centres of ancient times. The site and baths of Aquae Calidae have been visited in the course of history by several important rulers from Philip II of Macedon to the Eastern Roman emperors Justinian I and Constantine IV, the Bulgarian ruler Terwel and the Ottoman Sultan
Aphanizomenon flos-aquae (dietary supplement) from the air, and water to synthesize proteins, carbohydrates, and lipids. AFA is also able to directly use molecular nitrogen from the air to produce proteins and other nitrogen-containing biomolecules. This ability is widespread in prokaryotes, but unknown in eukaryotes. "Aphanizomenon flos-aquae" as a species has both toxic and non-toxic forms. While benefits have been indicated, toxicity has been shown in some strains of the species "Aphanizomenon flos-aquae", with cylindrospermopsin and saxitoxins present, and microcystins found contaminating AFA dietary supplements. The World Health Organization's "Guidelines For Drinking Water Quality" note Anatoxin-a, saxitoxins, and cylindrospermopsins are present in the Aphanizomenon genus.