The Genus Haliscomenobacter
In the 1st edition of The Prokaryotes, the genus Haliscomenobacter was considered together with bacteria of the genera Sphaerotilus and Leptothrix, but Haliscomenobacter is not closely related to these other Gram-negative sheathed bactera.
- PDF / 412,510 Bytes
- 3 Pages / 539 x 751 pts Page_size
- 13 Downloads / 223 Views
CHAPTER 6.9 ehT
suneG
re t cabonemoc s i l aH
The Genus Haliscomenobacter EPPE GERKE MULDER AND MARIA H. DEINEMA
In the 1st edition of The Prokaryotes, the genus Haliscomenobacter was considered together with bacteria of the genera Sphaerotilus and Leptothrix, but Haliscomenobacter is not closely related to these other Gram-negative sheathed bactera.
Habitats Strains of Haliscomenobacter hydrossis, the only species of the genus Haliscomenobacter isolated so far, are nearly always present in activated sludge flocs, sometimes in large amounts. The conditions for such an abundant development, which gives rise to bulking sludge, are not understood. Straight, thin, needle-shaped, sheath-forming chains of cells protruding from the sludge flocs (Fig. 1) may interfere with clumping and compacting of the solids.
Isolation The following procedure (van Veen, 1973) can successfully be used to isolate Haliscomenobacter sp. from bulking activated sludge. I Medium (g/liter of distilled water) Glucose (NH4)2SO4 Ca(NO3)2 K2HPO4 MgSO4 · 7H2O KCl CaCO3 Vitamin B12 Thiamine Agar (Oxoid)
0.15 0.5 0.01 0.05 0.05 0.05 0.1 10-5 4 ¥ 10-4 10
Preservation of Cultures
S.C.Y. Medium (g/liter of distilled water) Sucrose Casitone (Difco) Yeast extract (Difco) Trypticase soy broth without dextrose (BBL) Vitamin B12 Thiamine Agar (Oxoid)
A sample of 0.10–0.50 ml of sludge with a relatively large amount of Haliscomenobacter threads is pipetted into tubes containing 10 ml sterile tap water. The tubes are stirred for several minutes with a tube mixer and the flocs allowed to settle. The settling time depends on the characteristics of the sludge and especially on the degree of bulking. This treatment of the sludge is repeated until sufficient filamentous organisms are observed microscopically in the upper layers of the supernatant. During moderate agitation and rotating movements of the dilute floc suspensions, fragments of threads are severed from the protruding filaments. The low total numbers of organisms and the favorable ratio between filamentous and other bacteria in the upper liquid layers permit a direct inoculation of the plates without further dilution of the suspension. The time of agitation of the flocs in the tubes appears to be related to the mechanical properties of the stirrer and to the nature and number of filamentous organisms present in activated sludge. Very small droplets containing sufficient numbers of filamentous bacteria are transferred to the previously dried surfaces of 30 to 40 agar plates containing I medium. The cells are regularly spread over the whole surface of the agar plates by rubbing firmly with a sterile glass rod. The plates are incubated for 3 to 4 weeks at a temperature between 17 and 20∞C. The small colonies that develop from filamentous bacteria are often difficult to detect with a stereomicroscope, but recognition of the poorly contrasting, filamentous microcolonies on the agar is facilitated by low-magnification (150¥) phase-contrast microscopy. Isolation is performed by transferring bacterial cells to S.C.Y. mediu
Data Loading...
