Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>A novel approach for biological control of insect pests could be the use of the endophytic entomopathogenic <jats:italic>Beauveria bassiana</jats:italic> isolate ATP-02. For the utilization of the endophyte as a commercial biocontrol agent, the fungus has to be mass-produced. <jats:italic>B. bassiana</jats:italic> was raised in shake flask cultures to produce high concentrations of total spores (TS), which include blastospores (BS) and submerged conidiospores (SCS). The highest concentration of 1.33×10<jats:sup>9</jats:sup> TS/mL and the highest yield of 5.32×10<jats:sup>10</jats:sup> TS/g sucrose was obtained in the TKI broth with 5% sugar beet molasses which consists of 50% sucrose as a carbon source. In spite of the lower sugar concentration (2.5%) the amount of TS could be increased up to 11-times in contrast to the cultivation with 5% sucrose. The scale-up to a 2 L stirred tank reactor was carried out at 25°C, 200–600 rpm and 1 vvm at pH 5.5. A TS yield of 5.2×10<jats:sup>10</jats:sup> TS/g sucrose corresponding to a SCS yield of 0.2×10<jats:sup>10</jats:sup> SCS/g sucrose was obtained after 216 h. With regards to the culture medium the cost of 10<jats:sup>12</jats:sup> TS amounts to 0.24 €. <jats:italic>Plutella xylostella</jats:italic> larvae, which were fed with oilseed rape leaves treated with spores from fermentation resulted in 77 ± 5% mortality. Moreover, spores from submerged cultivation were able to colonize oilseed rape leaves via leaf application. This is the first report of fermentation of an endophytic <jats:italic>B. bassiana</jats:italic> strain in a low-cost culture medium to very high yields of TS.</jats:p>