Annual variations in the microflora of some varieties of Finnish malting barley

Abstract

Three major Finnish malting barley varieties were studied for annual variations in the incidence of seed-derived fungi, bacteria and actinomycetes. In 1990-1992, 114 characterized fungal, 59 uncharacterized bacterial and 12 uncharacterized actinomycetal isolates were extracted from samples of seed intended for use in malting. When the yield of the plant hormone, indole-3-acetic acid (lAA), from enriched microbial cultures was weighed against the microbial biomass and the endogenous lAA concentration of the barley harvests, it was concluded that potential exists for bacterial lAA production in biologically significant amounts, given some minor annual variations. As expected from the average rainfall and temperature during the growing season, microbial counts in all cultivars were highest in 1992. Most of the fungal species found were of saphrophytic character, and field fungi were dominant in the samples. On the whole, microbial counts and spectra in all samples confirmed that each harvest of all cultivars was of good vigour and well suited for malting purposes. Strains of plant pathogenic character included species of Septoria nodorum (Berk) Berk, Drechlera teres (Sacc) Subraim & Jain, D. sorokiniana (Sacc) Subram & Jain and D. graminea (Rab.) Shoem. A consistent difference was noted in the microbial infection severities of the cultivars.

Yeasts in an industrial malting ecosystem

“…In agreement with previous investigations [24,25,49,52,69], the red-pigmented yeasts Rhodotorula and Sporobolomyces were important members of the malting ecosystem. Rhodotorula species can be found from a variety of substrates and environments world-wide [39].…”

“…The following six basidiomycetous yeasts: C. albidus, Cryptococcus sp. R. glutinis, R. mucilaginosa, S. roseus and T. beigelii have previously been reported in the malting process [15,21,23,25,49,52,69]. We found 11 diVerent Cryptococcus species in the malting process including four potentially novel species.…”