Aleksandr Alekseyevich Mil'ko was born in Moldova in 1926, but moved to Ukraine in the early 1950s, when he defended his candidate degree thesis on soil fungi under the supervision of N.M. Pidoplichko, a Corresponding Member of Ukrainian Academy of Sciences. At the beginning of the 1960s, he moved to Kiev for domestic reasons. At first he worked at the Institute of Hydrobiology, National Academy of Sciences of Ukraine, after that he moved to the D.K. Zabolotny Institute of Microbiology & Virology, where he worked in the Department of Mycology under the direction of N.M. Pidoplichko. At the same time he published his early works on fungi of the order Mucorales, which became his research topic for the next ten years. His first work, devoted to fungi of the genus Gongronella Ribaldi, was published in 1961. It became clear, that a new expert on these moulds had appeared in Ukraine, someone who was afraid to pose and then solve taxonomic questions in such a complicated order of fungi. He began his study on moulds by accumulating pure cultures which he extracted from soil, water, excrement and decaying plant remains. The substrata from which these cultures were extracted were collected in different regions of the USSR and in different countries of central Europe (Bulgaria, Czechoslovakia, Germany, Poland, and Rumania). He also obtained cultures of about 100 mould species from collections in India, Japan, the Netherlands, the UK, the USA and through the All-Union Collection of Micro-organisms in Moscow.

Using these pure cultures, Mil'ko studied the morphology of moulds at different stages of development: vegetative mycelium, and organs of asexual and sexual reproduction (sporangia, stylosporangia, merosporangia and zygospores). By the same means he studied the phenomenon of homo- and heterothallism, so important in different mould species. Besides morphological characteristic, he also described different types of mould colonies, using experiments to determine their physiological characteristics, including their responses to different sources of N, P and S, to micro-elements, and to pH, humidity and temperature.

His consequent understanding of morphological, physiological and ecological characteristics of moulds enabled him to frame a hypothesis about the evolution of this group. He postulated that evolution of the Mucorales was connected with their fitness for terrestrial conditions, i.e. to low humidity, drastic temperature oscillations and solar radiation. As a result, their hyphae and organs of asexual reproduction became cutinized. The development of these apparatus implied a decline in significance of sexual reproduction. Based on this, Mil'ko regarded the family Mortierellaceae (occurring in wetter habitats and characterized by a thin, poorly cutinized envelope and simple ephemeral sporangia) as the most ancient. From this family, he derived two evolutionary lines. The first "sporangial" or "endogenous" line, evolved in the direction of a thicker enlarged sporangial envelope leading to a column, i.e. to the inversion of a sporangium into a stylosporangium. Within this line he placed the Endogonaceae, Mucoraceae, Pilobolaceae and Thamnidiaceae. The second "conidial" or "exogenous" line, was derived either from the Thamnidiaceae or from the Mortierellaceae. In the case of the Thamnidiaceae, Mil'ko regarded conidial forms of the genus Choanephora as ancient, because of the loss of their ability to develop sporangia and stylosporangia. In the case of the Mortierellaceae, he regarded the Mortierella capitata as ancient, due to a possible transformation of the sporangium into a merosporangium or conidium. In this group he included the Cunninghamellaceae, Dimargaritaceae, Kickxellaceae and Piptocephalidaceae.

His research on the order Mucorales, allowed hims to produce a Guide to the Identification of Moulds, which included 340 species from 43 genera and 8 families. In the guide he provided characteristics of subordinal taxa of different ranks, keys for their identification, original diagnoses of species, and information on their distribution. In this book, he also introduced his taxonomic innovations: 8 species new for science, 2 new genera, 1 new section and 15 new nomenclatural combinations. In 1970 all these scientific works were summarised in his doctoral thesis Fungi of the order Mucorales: Systematics. The identification key in the systematic part of this work was illustrated by 500 photographs and photomicrographs of 165 species and varieties from 40 genera. A year after the defence, along with N.M. Pidoplichko, he edited these illustrations as an Atlas of Mould Fungi (1971). In 1974 the systematic part of his doctoral thesis was published as a separate book, Guide to the Identification of Moulds.

After finishing his work on moulds, Mil'ko began research on the Oomycetes. He was particularly interested in representatives of the order Saprolegniales. In 1979, most probably, in connexion with the characteristics of this group (Saprolegniales prefer watery habitats) and the necessity of using of hydrobiological approaches in their research, Mil'ko moved to the Institute of Land Water, USSR Academy of Sciences, Borok, Yaroslavl' oblast, Russia. Here he held a position as head of the Laboratory of Lower Organisms. In this laboratory he established a group of mycologists, which studied fungi of water ecosystems. Along with his colleagues, Mil'ko also studied spore-forming organisms in Volga reservoirs and some northern reservoirs within the project to redirect northern waters into the Volga river. Assessment of the abundance of spore-forming organisms was carried out taking into account such factors as depth and water contamination by industrial enterprises. Mil'ko initiated research into fish of Volga reservoirs, ponds of the Darwin Reserve (Vologda oblast, Russia), Lake Ladoga, Lake Balkhash and Lake Issyk-Kul; he also began to study fungi on dead remains of larger plants in the upper Volga basin, and to determine the proteolytic activity of aquatic fungi. At the same time he carried on taxonomic analysis and preparation of identification tables for two large genera of the Saprolegniales: Saprolegnia and Achlya. As in the case of mould fungi, he paid special attention to use of pure cultures of the Saprolegniales. To study species of the genus Saprolegnia, he extracted about 900 cultures from water, soil and peat; and for genus Achlya, about 500 cultures. He also used pure cultures obtained from collections in the the Netherlands, the UK and the USA. As a consequence of these studies, he drew up and published tables for identification of 23 species of Saprolegnia and 33 species of Achlya. A diagnosis was provided for all species of the Saprolegniales included in the keys, with in indication of which cultures were studied. Synonyms were listed, and the general world distribution of each species was also presented. At the end of the work, he listed doubtful or excluded species, 20 for Saprolegnia and 18 for Achlya. Unfortunately, Mil'ko never managed to prepare an identification guide which included representatives of all genera of the order Saprolegniales and the book, which he intended to write, was never finished. In 1985, he retired on a pension from the Institute of Land Water, Academy of Sciences of the USSR, and returned to Kiev.

Lists. Publications. Taxa. Kirk & Ansell form of name: Milko.