EFFECT OF SPECIFIC SUPPLEMENTS ON THE GROWTH PROPERTIES OF WORT AGAR DURING CULTIVATION OF PRODUCTION STRAINS OF DERMATOPHYTES

Dermatophytes of the genus Trichophyton, particularly Trichophyton verrucosum, are the main causative agents of trichophytosis in cattle. Cultivation of these microorganisms on solid nutrient media is associated with several difficulties: most T. verrucosum strains have stringent vitamin requirements for growth, their cultures are frequently contaminated by bacterial microflora, and biomass and spore productivity on standard media remain insufficient for industrial vaccine production. Therefore, optimization of the basal wort agar medium through the addition of specific supplements that improve its growth-promoting properties is an important objective.
Objective. To evaluate the effects of glycerol, inositol, L-histidine, and chloramphenicol on the growth-promoting properties of wort agar during cultivation of production strains of Trichophyton verrucosum and Trichophyton mentagrophytes.
Materials and Methods. Standard wort agar was used as the basal medium. Experimental media were supplemented with glycerol (0.5-2.5%), inositol (0.005-0.1%), L-histidine (0.005-0.2 g/L), and chloramphenicol (0.01-0.05 g/L). Growth properties were assessed based on linear growth rate, sporulation intensity, and mycelial productivity.
Results. Glycerol at a concentration of 1.5-2.0% increased the linear growth rate of T. verrucosum strain No. 123 by 28.3% and mycelial productivity by 25.6% compared with the control. Inositol at a concentration of 0.02-0.03% increased the number of microconidia from 45.2 to 73.0 million/cm³. L-histidine at a concentration of 0.02-0.04 g/L exerted a moderate stimulatory effect on the growth of T. mentagrophytes. Chloramphenicol at a concentration of 0.025 g/L completely inhibited visible growth of contaminating bacterial microflora without suppressing dermatophyte growth. The combined use of these additives increased the total yield of microconidia by 53.4% compared with standard wort agar.
Conclusion. Supplementation of wort agar with glycerol (1.5-2.0% for T. verrucosum and 2.0- 2.5% for T. mentagrophytes), inositol (0.02-0.03%), L-histidine (0.02-0.04 g/L), and chloramphenicol (0.025 g/L) significantly improves the growth-promoting properties of the medium, increases the productivity of production dermatophyte cultures, and provides effective control of bacterial contamination.

1. STO 9384-168-89767728-2015. Standart organizatsii. Vaktsina TVM [Organization Standard. Vaccine TVM]. OOO Firma «BioKhimFarm», g. Raduzhnyi, 2018. (In Russ.)

2. Zaitseva V.V., Krasochko I.A. (2015) Vliyanie sostava plotnoi pitatel'noi sredy na produktivnost' dermatofitov [Effect of solid nutrient medium composition on dermatophyte productivity]. Ekologiya i zhivotnyi mir, no. 1, pp. 53–59. (In Russ.)

3. Zaitseva V.V., Krasochko I.A. (2017) Optimizatsiya vyrashchivaniya dermatofitov na pitatel'nykh sredakh raznogo sostava [Optimization of dermatophyte cultivation on nutrient media of different composition]. Uchenye zapiski Vitebskoi gosudarstvennoi akademii veterinarnoi meditsiny, vol. 53, no. 2, pp. 78–82. (In Russ.)

4. Robbins W.J., Mackinnon J.E., Ma R. (1945) Vitamin requirements of dermatophytes. Bulletin of the Torrey Botanical Club, vol. 72, pp. 509–523. DOI: 10.2307/2481615.

5. Balabanoff V.A., Strashilova M. (1970) Comparative physiological studies on saprophytic and pathogenic dermatophytes. II. Growth factors. Mykosen, vol. 13, no. 10, pp. 499–504. DOI: 10.1111/j.1439-0507.1970.tb00654.x.

6. Philpot C.M. (1977) The use of nutritional tests for the differentiation of dermatophytes. Sabouraudia, vol. 15, no. 2, pp. 141–150. DOI: 10.1080/00362177785190221.

7. Robbins W.J., Ma R. (1945) A growth factor for Trichophyton verrucosum. American Journal of Botany, vol. 32, p. 509.

8. Arendrup M.C., Guinea J., Meletiadis J., Jorgensen K.M. (2018) EUCAST susceptibility testing of Trichophyton rubrum: chloramphenicol and cycloheximide supplemented growth medium improve assay performance. Meeting Abstract.

9. Patent RF № 2275631. Sposob diagnostiki dermatomikozov i pitatel'naya sreda dlya dermatofitov [Method for diagnosing dermatomycoses and culture medium for dermatophytes]. 2006. (In Russ.)

10. Aleshkevich V.N., Medvedev A.P., Kuleshov D.B. (2018) Stimulyatsiya rosta i razmnozheniya dermatofitov [Stimulation of growth and reproduction of dermatophytes]. Veterinarnyi zhurnal Belarusi, no. 1, pp. 41–45. (In Russ.)

11. Zaitseva V.V., Krasochko I.A. (2014) Vliyanie komponentov mikroorganizmov na produktivnost' dermatofitov na suslo-agare [Influence of microorganism components on dermatophyte productivity on wort agar]. Vestnik Vitebskogo gosudarstvennogo universiteta, no. 8, pp. 45–51. (In Russ.)

12. Aly R. (1994) Culture media for growing dermatophytes. Journal of the American Academy of Dermatology, vol. 31, no. 3, pp. S107–S108. DOI: 10.1016/S0190-9622(94)70277-0.