Screening of yeast from oxytetracycline fermentation residue and optimization of the fermentation conditions

Abstract:

[Background] With the development of pharmaceutical industry, an enormous amount of antibiotic fermentation residue is produced every year in China, which has caused environmental pollution and waste of resources. However, the residue is rich in proteins and other nutrients which can be used for secondary production, making it possible for effective utilization of the residue. [Objective] To screen yeast from oxytetracycline fermentation residue and optimize the culture conditions of the yeast in the medium with the residue as the main component for resource utilization of oxytetracycline fermentation residue. [Methods] Yeast strain was screened from oxytetracycline fermentation residue with the serial dilution-agar plating method. The strain was then identified through morphological observation and 18S rRNA sequence analysis. Single-factor experiment and Box-Behnken design were used to optimize the culture conditions and determine the optimal growth conditions of the strain in the medium with oxytetracycline fermentation residue as the main component. [Results] The Zygoascus hellenicus Y1 strain was screened out. The optimum culture conditions are as follows: oxytetracycline fermentation residue at 5%, glucose at 0.5%, inoculum at 2%, pH 5.0, 32 ℃, 160 r/min, 24 h. [Conclusion] Y1, which can make full use of the oxytetracycline fermentation residue for growth, was screened out, realizing the resource utilization of the residue and reducing the discharge of bacterial residue. The result lays a foundation for the preparation of yeast extract with oxytetracycline fermentation residue.

Key words:oxytetracycline fermentation residue;yeast;identification of strain;optimization of fermentation conditions