The Genera Caulococcus and Kusnezovia
Perfil’ev and Gabe (1965) observed bacteria of the genera Caulococcus and Kusnezovia, along with Metallogenium and Siderococcus, as manganese- and, to a lesser extent, iron-depositing or -oxidizing organisms of mud and sandy de-posits. The use of capillar
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CHAPTER 14.8 succoco l uaC
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The Genera Caulococcus and Kusnezovia JEAN M. SCHMIDT AND GEORGI A. ZAVARZIN
Perfil’ev and Gabe (1965) observed bacteria of the genera Caulococcus and Kusnezovia, along with Metallogenium and Siderococcus, as manganese- and, to a lesser extent, iron-depositing or oxidizing organisms of mud and sandy de-posits. The use of capillary devices that permit microscopic observation (peloscopes) has permitted some observations of structure and colonial morphologies. Their morphologies suggest that these organisms might be related to Acholeplasma, Metallogenium, or Siderococcus, but lack of axenic cultures has prevented thorough study of their physiology and composition; understanding of the nature of these rather rare bacteria is quite meager.
Habitats Caulococcus has been found in samples of mud and sandy deposits as observed with microcapillary techniques (Kutuzova et al., 1972; Perfil’ev and Gabe, 1961; Perfil’ev et al., 1965). It was originally found in Lake Khepo-Yarvi (Karelian Isthmus), “especially in ore deposits,” and was “frequently observed in the upper layers of bottom mud deposits, above the reducing horizon,” or in the bottom water (periphyton) over the mud (fine mineral or sandy) surface (Perfil’ev et al., 1965). Kusnezovia was observed, using the peloscope technique, only “in mud samples from Lake Ukshezero, Karelian ASSR” (Perfil’ev et al., 1965), and in secondary profiles in zones of manganese oxidation of mud samples stored in the laboratory. As described by Perfil’ev and Gabe (1965), in capillary peloscope samples from many orebearing lakes, for all those “with a black-orange microzone, the blackish-brown horizon of the microzone in the peloscope canals showed a mass-development of Metallogenium, rarely Caulococcus, and sometimes Kusnezovia, the biogenic deposits of which consist mostly of manganese oxides.”
This chapter was taken unchanged from the second edition.
Isolation Neither Caulococcus nor Kusnezovia has been isolated in pure culture. Distinctive morphologies, particularly those of microcolonies using microcapillary techniques, have been used to define these two groups (Perfil’ev et al., 1965). Organisms could be maintained in the isolated samples of mud (Perfil’ev et al., 1965): a sample of water (approximately 1/3) and mud (2/3) from the natural habitat was mixed thoroughly and incubated in a 200-ml beaker at room temperature for months. Peloscopes were placed across the upper 3 cm of the mud. Development of manganese- and iron-depositing organisms was observed to occur in sharp, horizontal microzones (a few millimeters in width) in the upper layers of mud following the reduction of metal oxides in the bottom layers.
Identification In the absence of axenic cultures and information on cultural traits, colonial morphology is used, along with the characteristic manganese deposition, for tentative recognition of these kinds of bacteria. To observe cell morphology, Perfil’ev and Gabe (1965) dissolved manganese deposits with 0.2–1.0% oxalic acid, washed them with
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