Media and Conditions for the Growth of Halophilic and Halotolerant Bacteria and Archaea

An awareness of haloarchaea has existed since ancient times, with published descriptions of “red waters” associated with salt mining, the “red heat” of salted hides, and the “reddening” of salted fish (Bass-Becking 1931; Kurlansky 2002). For a society without refrigeration, the economic impact of codfish deterioration garnered particular attention, with Farlow (1878) oft cited as the first to publish on what were presumably haloarchaea. The early growth media of Eddington (1887) and Le Dantec (1891) reflected natural high-protein substrates, using beef peptone, gelatins, and fish broths, solidified with agar, flour, or bread paste. While some early studies used pieces of fish soaked in various brines (Høye 1908; Klebahn 1919; Harrison and Kennedy 1922), many included ground cod or a cod broth, or media based on beef bouillon or beef gelatin (Beckwith 1911; Bitting 1911; Becker 1912; Kellerman 1915; Clayton and Gibbs 1927; Velu 1929). Milk was introduced as a preferred organic constituent by Bitting (1911) and Kellerman (1915), but was popularized by Lockhead (1934). Rice flour, wheat flour or whole rice grains often were used as gelling agents (Clayton and Gibbs 1927; Robertson 1931; Boury 1934; Gibbons 1937). Silica gel was suggested to reduce organic content of solidified media (Hanks and Weintraub 1936; Moore 1940, 1941). It was recognized that alkaline culture conditions were useful for growing certain halophilic microbes (Stather and Liebscher 1929) and that halophilic obligate anaerobes could be grown on a cooked meat medium (Baumgartner 1937). The seminal paper of Harrison and Kennedy (1922) focused on the difficulties of growing the organisms responsible for red discolorations on salted fish, trying many media recipes including those based on cider, milk, broths, sugars, and potatoes. While the red organisms proved difficult to isolate, as an aside, the paper discusses a broad diversity of non-red halophilic organisms that were more easily isolated on these media.