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Showing 2 results for Thermotolerance
F. Moghadami, M.r. Soudi ,
Volume 9, Issue 2 (9-2018)
Abstract
Aims: Adaptation of native bacterial strains in every climate is considerable. Evaluation of native thermotolerant acetic acid bacteria effectively influence their optimal and beneficial use. The aim of this study was to evaluate the characteristics of productive thermotolerant acetic acid bacteria with focusing on Acetobacter sp. A10.
Materials and Methods: In the present experimental study, the native thermotolerant strain of Acetobacter sp. A10 was used. For preparation of fresh culture and maintenance of thermotolerant strain glucose yeast extract calcium carbonate was used, which contained 50g glucose, 10g yeast extract, 30g calcium carbonate, and 25g agar per liter. In order to produce acetic acid by the strain of Acetobacter sp. A10, ethanol yeast extract broth culture was used. Effect of initial concentrations of ethanol and acetic acid on the production of acetic acid by Acetobacter sp. A10 was investigated, using a culture meda containing 2% to 9% ethanol and 2% to 9% acetic acid.
Findings: This strain could produce 40g/l acetic acid from 4% (WV) ethanol in baffled shake-flasks in 24h under optimized conditions of pH 4, at 33°C, and 150rpm. The strain at 37 °C was able to produce acetic acid in the presence of a 4% and 8% initial concentration of acetic acid a. The rate of fermentation was 2.5 times more than mesophilic ones.
Conclusion: Acetobacter sp. A10 is active in a different temperature range compared to mesophilic strains and it is able to withstand ethanol and acetic acid to more concentrations. In addition, it has higher efficiency, as well as greater rate and power of fermentation.
Volume 15, Issue 2 (3-2013)
Abstract
Production of lignocellulolytic enzymes by the thermotolerant Fomes sp. EUM1 was determined in solid cultures using corn stover (CS) as a sole substrate or supplemented with 20 % wheat bran (CS+WB). This supplementation increased (P< 0.05) enzymatic activity per gram of initial dry matter (gdm) for xylanases and cellulases: 160 IU g dm-1 and 37 IU g dm-1, respectively; while laccases reached a similar yield (3.3 IU g dm-1) for both cultures. Nevertheless, laccases showed different stability patterns at 39°C and pH 6: half-life time (t½) was doubled in extracts from CS+WB (23.5 h); whereas t½ for the other enzymes from both cultures showed no difference. Both extracts by Fomes sp. EUM1 and a commercial enzymatic product were used on forages: corn stover, (CS), sugarcane bagasse (SCB), and alfalfa hay (AH). The fractional rate of gas production (FR; ml g-1 h-1) increased (P< 0.05) at 9 hours in CS compared to the sample without enzymes. The use of any enzymes favoured higher maximum gas volume (Vm; h-1) on SCB. The in vitro digestibility (IVD) of CS after using the commercial product was 12% higher, while our extracts from CS and CS+WB showed 16 and 21% improvements (P< 0.05), respectively, suggesting a higher specificity of these enzymes produced on the same substrate (CS). In addition to the proven stability, the versatility of extracts from CS and CS+WB was confirmed by the increase in IVD values for SCB (up to 100%) in relation to the control without enzymes.
