Application of a Posttreatment to Improve the Viability and Antifungal Activity of Trichoderma asperellum Biomass Obtained in a Bioreactor during Submerged Cultivation

Abstract

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.

Impact of Growth Conditions on the Viability of Trichoderma asperellum during Storage

“…By adding substances that reduce T. asperellum metabolic activity to the biomass, the shelf life of the biomass can be extended, thus maintaining the competitiveness of the microorganisms against plant pathogens. Decreasing the biomass pH can suppress the metabolic rate, thereby improving microbial survival [14,36,47]. This approach, decreasing the pH to 4 at the end of cultivation in a bioreactor, was successfully applied in the present study.…”

“…Moisture content was determined by heating the biomass in an AGS 120/T250 moisture analyzer (Axis, Gda ńsk, Poland) at 85 • C for 25 min. To detect dry weight from the biomass on the Petri dish, a method from Senkovs et al (2022) [36] was used. In each experiment, the highest biomass reached was taken as 100% dry weight, and percentages were adjusted respectively for all biomass from other media.…”

“…T. asperellum strain MSCL 309 inhibits the growth of the conifer root and butt rot fungi Heterobasidion annosum s.s. and H. parviporum, which gives it a high potential for use against phytopathogens. [35] T. asperellum MSCL 309 can maintain its viability and antifungal activity for a long time, with or without different post-treatment methods [36]. To investigate the storage conditions, regular and accelerated storage tests [37] were applied.…”

Influence of Carbon and Nitrogen Sources on Biomass Yield and Fungistatic Activity of Trichoderma Viride KMB-F-15

“…Surface solid-phase cultivation allows the use of various agroindustrial wastes and requires less investment, but this process is difficult to scale [10]. Whereas the advantages of submerged cultivation include short cultivation time, less labour intensity, ease of management and the possibility of automation [11,12].…”

“…Поверхневе твердофазне культивування дозволяє використовувати різні агропромислові відходи і потребує менших капіталовкладень, проте такий процес складно масштабувати [10]. Тоді як до переваг глибинного культивування відносяться короткий час культивування, менша трудомісткість, простота управління та можливість автоматизації [11,12].…”