The used strains are thermophilic bacteria, frequently utilized in our processes at technical scale. In studies taking place Trichostatin A cell line under non-sterile conditions, B. coagulans was shown to be the most predominant species [1]. Furthermore, the B. coagulans strains are known for their inhibitor tolerance [17] and their capability of utilizing pentose sugars from the hemicellulose fraction of lignocellulose [24]. These facts provide for the possibility to ferment difficult media under semi-sterile condition. Prior the fermentation

in technical and pilot scale, kinetic data is needed to gain a basic understanding of the characteristics of the MOs for later fermentation processes and their design. Growth models are used to obtain the basic growth parameters, such as specific growth rate and duration of lag phase, in order to classify and differentiate microorganisms in respect to their behaviour towards diverse lignin concentrations. Numerous models were developed for the representation of growth curves. Widely known models ABT-199 are the logistic [28], Gompertz [14], [25], [26] and [28], Champbell-Richards and Stannard [28], and the model offered by József Baranyi [3]. These models have been established to

fit the equations to the sigmoidal shape of a typical growth curve. Bacillus coagulans strains were isolated from different environmental areas. They were stored in cryogenic vials (VWR, 822074ZA) at −70 °C and reactivated on MRS broth (Merck, 1.10661.0500) at 52 °C for 24 h). After reactivation the microorganisms were cultivated on slant culture tubes with MRS agar (Merck, 1.10660.0500) and stored at 4 °C for further use in inocula. The used strains were officially microbiologically characterised through the Leibniz Institute’s

German Collection of Microorganisms and Cell Cultures (DSMZ). Strain-1 (DSM No. 2314) was isolated from potato washing water, strain-2 (DSM ID 14-301) was isolated from chicken feed, and strain-3 (DSM ID: 14-298) was isolated from rotten foliage. Inocula were cultivated on 60 ml MRS (Merck, 1.10661.0500) broth in shaking flasks (52 °C, Anidulafungin (LY303366) 100 rpm, 15 h). These were transferred into 5 ml tubes for centrifugation (5000 rpm, 15 min, 4 °C). Centrifuged bacteria were resuspended in minimal medium for the lignin test (60 g/l d-(+)-glucose, 5 g/l yeast extract, 0.025 mol/l sodium-acetate-buffer at pH 6.0). A set of five different lignin concentrations (Sigma, 471003), (0.0, 0.2, 0.4, 0.6,and 0.8 g/l) was applied. A Bioscreen C from Oy Growth Curves Ab Ltd., was used for the optical density experiments. Measurements were taken with a wide band filter (420–580 nm). For the calibration curve, Bioscreen C microarray honeycomb plates were prepared as follows: all wells, except the wells of the 10th row, were filled with 250 μl of the minimal medium. The wells of the 10th row were filled with 500 μl inocula. 250 μl were removed from these wells and transferred into the next upper row.