Growth of Debaryomyces hansenii in Seawater Culture Medium
Comparison of Debaryomyces hansenii growth at various salt concentrations and seawater-formulated media and determination of its halotolerance.
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Protocol
Growth of Debaryomyces hansenii in Seawater Culture Medium Martin Ramirez-Orozco and Jose Luis Ochoa
Aim Comparison of Debaryomyces hansenii growth at various salt concentrations and seawater-formulated media and determination of its halotolerance.
Introduction The marine yeasts may be considered a potential source of products of biomedical and industrial interest (Nell 1993; Rhishipal and Philip 1998; Urano et al. 1998; Scholz et al. 1999). However, their use and applications are scarce, probably because current fermentation procedures and equipment are designed to operate with microorganisms that grow best at low salt concentrations. The use of seawater as a solvent in medium preparation, or of media containing high salt concentration, in industrial processes is limited mainly by corrosion risks. However, one advantage of carrying out a largescale biomass production in seawater is a reduced contamination risk, which may translate into lower operational costs. The marine yeasts seem to possess also another attractive ability for industrial application: they are able to develop in the sea under diluted nutrient conditions and this indicates a very efficient uptake and substrate Jose L. Ochoa (✉), The Center For Biological Research, CIBNOR, Box 128, La Paz, BCS, México 23000 (Tel.: +52-112-53633; Fax: +52-112-20598; e-mail: [email protected]) Martin Ramirez-Orozco, The Center For Biological Research, CIBNOR, Box 128, La Paz, BCS, México 23000 email: [email protected];
Springer Lab Manual K. Wolf, K. Breunig, G. Barth (Eds.) Non-Conventional Yeasts in Genetics, Biochemistry and Biotechnology © Springer-Verlag Berlin Heidelberg 2003
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Martin Ramírez-Orozco and Jose Luis Ochoa
assimilation. Moreover, under optimum conditions in the laboratory, they show high growth rates and capacity to assimilate a large variety of carbon sources,thus making it possible to select the most appropriate substrates on the basis of availability and price for large-scale processes (Hagashihara et al. 1983; Rhishipal and Philip 1998). In this experiment we will review the effect of salt concentration and of seawater in Debaryomyces hansenii growth using glucose as carbon source.
Materials Strains
Apparatus
Debaryomyces hansenii can be obtained from an official collection, such as ATCC or CBS, and is also available from CIBNOR marine yeast collection upon request (Hernández-Saavedra 1990). –
UV-VIS spectrophotometer
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Orbital shaker.
Media
The Debaryomyces hansenii culture medium of choice is M1 and can be prepared as indicated below.
Reagents
M1 is prepared with 2 % glucose, 1 % peptone, 0.5 % yeast extract in filtered seawater, and the pH is adjusted to 5.6 with 1 M NaOH or HCl.
Experimental Procedure Day 1
Yeast pre-inoculum is prepared from colonies obtained from slant tubes and suspended in 125 mL of M1 liquid medium and incubated for 18 h with orbital shaking (100 rpm) at 30 °C.
Day 2
After determining optical absorbance at 580 nm with a spectrophotometer (lecture must be about 0.45–0.5), 5 mL of this pr
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