SELECTION OF CELLULOLYTIC BACTERIA OF THE GENUS BACILLUS AND STUDY OF THEIR COMPATIBILITY WITH MICROMYCETE TRICHODERMA HARZIANUM PD3
Authors: Dimova S. B. , Shevchenko L. A. , Volkohon V. V. , Bondar I. M. , Zemska І. А. 
Published: November 2023

Objective. To isolate active strains of cellulolytic bacteria of the genus Bacillus from the natural environment and to study their compatibility with the micromycete Trichoderma harzianum PD3, which is used in the poultry manure-based technology of organic matter biocomposting. Methods. Microbiological (isolation of bacteria, checking the purity of cultures, microscopy, selection according to the degree of destruction of cellulose-containing substrates, determination of the compatibility of selected bacteria and micromycete by the counterculture method, identification by morphological and cultural properties and using the MALDI-TOF method on an automatic bacteriological analyser), physiological (biotesting of bacterial culture fluids of bacteria), statistical. Results. As a result of the selection of cellulolytic bacteria of the genus Bacillus isolated from various natural substrates, 7 strains were pre-selected, which were found to be the most active destroyers of three cellulose-containing substrates (filter paper, straw, and carboxymethyl cellulose (CMC)). The degree of destruction of filter paper using these strains was from 19.5 % up to 24.9 %, while the collection strain Bacillus subtilis IMV B-7516, used in the experiment as a standard, decomposed paper by 19.3 %. The destruction of straw under the action of the studied strains was at the level of 9.8 % to 14.5 %, when this parameter in the standard strain is 8.8 %. All seven selected strains provided the formation of CMC hydrolysis zones of more than 30 mm in diameter (larger than the zone formed by the standard strain). Using the method of countercultures, it was found that Bacillus sp. 243 and 392 are incompatible with T. harzianum PD3, as the micromycete completely suppresses the growth of bacilli, which in further studies excludes the possibility of their co-use in organic matter composting technologies. The combined use of T. harzianum PD3 with B. amyloliquefaciens ssp plantarum 201 and 293, as well as B. amyloliquefaciens 425 is considered promising. The strains B. amyloliquefaciens 348 and B. megaterium 362, which effect on T. harzianum PD3 consisted in a slight limitation of the development of the micromycete, can also be used in further studies, however, with some precautions, for example, using the phased, time-separated introduction of trichoderma and the specified bacteria into composted substrates. The selected strains of bacilli are not phytotoxic. Culture fluids (CR) of these strains demonstrate a growth-stimulating effect. A specific test for auxin activity showed that the CR of all five selected bacillus strains stimulate the growth of wheat coleoptiles suggesting their ability to synthesize auxin-like phytohormones. A significant stimulatory effect was registered in 1/1,000 and 1/10,000 dilutions of culture liquid. Conclusion. The selected bacteria are active cellulolytics: B. amyloliquefaciens ssp. plantarum 201 and 293, B. megaterium 362, B. amyloliquefaciens 348 and 425, which, in addition to high cellulolytic ability, are producers of auxin substances, are not phytotoxic, compatible with the active cellulolytic micromycete T. harzianum PD3 and can be used in further studies with development of poultry manure-based technology of organic matter biocomposting.