Tag Archives: fermentation

256–269 M. Paiders, A. Gruduls, L. Kalnina, S. Valucka, I. Dimanta, J. Kleperis, and V. Nikolajeva
Biogas and hydrogen production from glycerol by Enterobacter aerogenes and anaerobic microbial communities
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Biogas and hydrogen production from glycerol by Enterobacter aerogenes and anaerobic microbial communities

M. Paiders¹*, A. Gruduls¹, L. Kalnina¹, S. Valucka¹, I. Dimanta¹², J. Kleperis², and V. Nikolajeva¹

¹University of Latvia, Faculty of Biology, Department of Microbiology and Biotechnology, Jelgavas street 1, LV-1004 Riga, Latvia
²University of Latvia, Institute of Solid State Physics, Laboratory of Hydrogen Energy Materials, Kengaraga street 8, LV-1063 Riga, Latvia
*Correspondence: matisspaiders@gmail.com

Abstract:

Biological hydrogen production by anaerobic fermentation of widely available renewable resources is a promising and advantageous area. Using microbiological hydrogen production from crude glycerol biodiesel-derived waste was utilized by obtaining renewable energy carrier. The purpose of this research was to study biogas and hydrogen production by Enterobacter aerogenes MSCL 758 and by natural microbial communities. Growth medium was supplemented with analytical grade, technical grade or crude glycerol. Inoculants from old municipal landfill, manure and lake sludge were also used. Biogas production was analyzed using Automatic Methane Potential Test System II. Part of the experiments were carried out in serum bottles and evolved gases were tested using mass-spectrometry. Fluorescence in situ hybridization was used for bacterial population dynamic determination. Optimal concentration for crude glycerol was found to be six grams per liter. Amount of hydrogen was significantly higher and amount of nitrogen gas was lower in case of analytical grade glycerol usage in comparison to crude glycerol fermentation. E. aerogenes acted in synergy with landfill substrate and manure in biogas production from technical grade and analytical grade glycerol. It was not the case for crude glycerol usage. Addition of E. aerogenes increased overall amount of produced hydrogen. Obtained results showed potential of E. aerogenes for use in bioaugmentation purposes for fermentation of glycerol. Lake sludge inoculum contained microorganisms necessary for the production of hydrogen as well as biogas from glycerol. Clostridia and Gammaproteobacteria were predominant in the inoculum. Cultivable bacteria Bacillus licheniformis, Burkholderia cepacia, Hafnia alvei and unidentified Clostridium species were found to be predominant after six days of fermentation.

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1074-1085 B. Shershenkov and E. Suchkova
Upgrading the technology of functional dairy products by means of fermentation process ultrasonic intensification
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Upgrading the technology of functional dairy products by means of fermentation process ultrasonic intensification

B. Shershenkov* and E. Suchkova

ITMO University, Institute of Refrigeration and Biotechnologies, Department of Technology of Milk and Food Biotechnology, Lomonosov str., 9, 191002, St. Petersburg, Russia; *Correspondence: boris.shershenkov@list.ru

Abstract:

Intensification of milk fermentation without negative influence on product quality is a priority research direction in dairy industry. One of the perspective tools for solving this problem is usage of ultrasound. Careful selection of ultrasonic treatment regimens allows to activate lactic-acid bacteria metabolic activity and to improve the efficiency of dairy production. A number of cultivations were carried out for ultrasonic processing effect estimation on Lactococcus mixed culture, Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus symbiotic cultures that are often used for dairy fermentation. Milk with added starter culture was treated with ultrasound by means of ultrasonic homogenizer at a frequency of about 30 kHz. Processing duration varied from 1 to 3 minutes and ultrasound power varied from 2 to 8 W. Ultrasonication regimens of fermenting milk allowed accelerating of fermentative process by 10% and improving the quality of final product.

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793-800 H. Kaldmäe, O. Kärt, A. Olt, A. Selge. I. Keres
Inoculant effects on red clover silage fermentation products and nutritive value
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Inoculant effects on red clover silage fermentation products and nutritive value

H. Kaldmäe¹, O. Kärt¹, A. Olt, A¹. Selge². I. Keres²

¹Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences,
²Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences,
Kreutzwaldi 1, EE51014 Tartu, Estonia; e-mail: helgi.kaldmae@emu.ee

Abstract:

The study investigated effects of five different microbial inoculants on silage fermentation and nutritive value. Silage was prepared from red clover-rich material with dry matter content after 24 hours of wilting of 170 g kgí1 for the first cut and 430 g kgí1 for the second cut. Tests with five different commercial inoculants were based on different strains of Lactobacillus plantarum which were used alone or in combinations with other lactic acid bacteria (1/BO, 2/BI, 3/SI, 4/EC, 5/BM), and chemical additive (CHEM) were used. Six commercial additives were compared with the untreated control. The additives were applied to fresh forage at the levels recommended by the manufacturers. Chemical compositions of the first and second cut of red clover were significantly different í crude protein 176 g kgí1 and 143 g kgí1 ; NDF 366 g kgí1 and 503 g kgí1 DM respectively. In the first trial, silages treated with 2/BI had lower levels of acetic acid 25.5 g kgí1 and ethanol 8.0 g kgí1 compared to the control values of 35.6 g kgí1 and 11.6 g kgí1 (P<0.05). Otherwise, the pH, and contents of ammonia nitrogen, ethanol and organic acids were no different from the control silage. In the second trial, silage treated with 1/BO and 4/EC showed the highest contents of lactic acid. Compared to the untreated control silage, the acetic acid content was lower in silages treated with 2/BI, 3/SI and 5/BM (P<0.05). The lactic acid:acetic acid ratio was higher in inoculated silages: for 1/BO, 2/BI; 3/SI, 4/EC and 5/BM it was 2.73; 2.17; 1.98; 2.03 and 2.87, respectively. The same ratio for the control silage was 1.83. All commercial inoculants improved the fermentation quality of red clover silage under the conditions stated. No differences were found between dry matter in vitro digestibility of the inoculated and the control silage for both the first and second cut. Digestibility of the red clover silage treated with CHEM was higher than that of the control silage by 4.6% for the first cut and by 7.3% for the second cut (P<0.001).

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