T. asperellum MSCL 309 was used in the study. T. asperellum was grown in the stirred bioreactor under submerged cultivation. The resulting biomass was filtered to obtain a thick biomass. The viability and antifungal activity of T. asperellum biomass samples were determined simultaneously by studying the colonization of the malt extract agar medium surface and its competitiveness with the plant pathogenic fungus Fusarium graminearum using in vitro dual culture experiments. Treatment with starch, alone or in combination with copper (II) sulphate and/or hydrochloric acid did not significantly affect fungal viability compared to control. An important factor in maintaining viability was the addition of hydrochloric acid, which significantly increased the storage life of biomass. In all post-treatments, F. graminearum was overgrown with T. asperellum in seven days, and accordingly, the larger the area occupied by T. asperellum, the smaller the area of F. graminearum colonization. Viability and antifungal activity of T. asperellum persisted throughout the experiment, at least for eight weeks. All the post-treatment methods we studied improved the viability and antifungal activity of Trichoderma, at least in terms of the area of the colonized surface. For the development of long-term viable and active T. asperellum preparations, we recommend the use of acidification of T. asperellum biomass obtained by submerged fermentation.

As excellent biocontrol agents and plant growth promoters, Trichoderma species are agriculturally important. Trichoderma spp. cultures can be produced using solid-state or submerged cultivation, the latter being much less labor intensive and easier to control and automate. The aim of the study was to investigate the ability to increase the shelf-life of T. asperellum cells by optimizing cultivation media and upscaling the submerged cultivation process. Four different cultivation media were used with or without the addition of Tween 80 and stored with or without incorporation into peat, and viability, expressed as CFU/g, was assessed during one year of storage in an industrial warehouse. The addition of Tween 80 had a positive effect on the biomass yield. The culture medium played a major role in the ability of the mycelium to produce spores, which in turn influenced the amount of CFU. This effect was less pronounced when the biomass was mixed with peat prior to storage. A procedure that increases the number of CFU in a peat-based product formulation is recommended, namely, incubation of the mixture at 30 °C for 10 days prior to storage at 15 °C over an extended period of time.