Proizvodnja limunske kiseline pomoću kvasaca uzgojenih na podlogama s glicerolom, dobivenim pri proizvodnji biodizela

The possibility of using glycerol and glycerol-containing waste from biodiesel manufacture as a carbon and energy source for microbiological production of citric acid has been studied. Acid formation on the selective media had previously been tested in 66 yeast strains of different genera (Candida, Pichia, Saccharomyces, Torulopsis and Yarrowia). Under growth limitation by nitrogen, 41 strains (belonging mainly to species Yarrowia lipolytica) produced acids; unlike 25 strains of the genera Debaryomyces, Candida, Pichia, Saccharomyces and Torulopsis. Among the 41 acid-producing strains, mutant strain Yarrowia lipolytica N15 was selected since it was able to produce citric acid presumably in high amounts. The citric acid production by the selected strain was studied in dependence on the medium pH, aeration and concentration of glycerol. Under optimal conditions, the mutant Y. lipolytica N15 produced up to 98 g/L of citric acid when grown in a fermentor with the medium containing pure glycerol, and 71 g/L of citric acid when grown on glycerol-containing waste. The effect of growth phases on physiological peculiarities of the citric acid producer was discussed.Ispitana je mogućnost uporabe glicerola i otpada bogatoga glicerolom, dobivenih pri proizvodnji biodizela, kao izvora ugljika i energije za mikrobnu proizvodnju limunske kiseline. Prethodno je ispitana proizvodnja limunske kiseline na selektivnim podlogama pomoću 66 sojeva kvasaca različitih vrsta (Candida, Pichia, Saccharomyces, Torulopsis i Yarrowia). Pri smanjenim koncentracijama dušika 41 soj (uglavnom vrste Yarrowia lipolytica) mogao je proizvesti limunsku kiselinu, dok 25 sojeva vrsta Debaryomyces, Candida, Pichiа, Saccharomyces i Torulopsis to nije moglo. Od 41 soja odabran je mutant Yarrowia lipolytica N15, jer je mogao proizvesti veliku količinu limunske kiseline. Ispitan je utjecaj pH-vrijednosti podloge, prozračivanja tijekom reakcije i koncentracije glicerola u podlozi na proizvodnju limunske kiseline pomoću toga soja. U optimalnim uvjetima u fermentoru mutant Yarrowia lipolytica N15 proizveo je do 98 g/L limunske kiseline na podlozi sa čistim glicerolom, a do 71 g/L limunske kiseline na podlozi s otpadom bogatim glicerolom. U radu se raspravlja i o utjecaju faze rasta na fiziološke značajke kvasaca pri proizvodnji limunske kiseline

Succinic Acid Synthesis by Ethanol-Grown Yeasts

The synthesis of succinic acid in ethanol-containing media has been tested in 32 yeasts of different genera (Debaryomyces, Candida, Pichia, Saccharomyces, Torulopsis). The capability of succinic acid synthesis was revealed in 29 strains, from which two most effective producers were selected. When grown in a fermentor under high aeration in mineral medium with pulsed addition of ethanol, the strain Candida catenulata VKM Y-5 produced succinic acid up to 5.2 g/L with mass yield of 32.6 % and energy yield of 14.8 %; the other strain, Candida zeylanoides VKM Y-2324, excreted 9.4 g/L of succinic acid with mass and energy yields of 39 and 17.8 %, respectively. It was indicated that succinic acid formation in the yeasts was accompanied by the synthesis of considerable amounts of malic acid, which was apparently due to a high activity of the glyoxylate cycle. Growth characteristics of both strains were studied in dependence on the concentrations of ethanol, zinc ions and nitrogen in the medium

Citric Acid Production by Yeast Grown on Glycerol-Containing Waste from Biodiesel Industry

The possibility of using glycerol and glycerol-containing waste from biodiesel manufacture as a carbon and energy source for microbiological production of citric acid has been studied. Acid formation on the selective media had previously been tested in 66 yeast strains of different genera (Candida, Pichia, Saccharomyces, Torulopsis and Yarrowia). Under growth limitation by nitrogen, 41 strains (belonging mainly to species Yarrowia lipolytica) produced acids; unlike 25 strains of the genera Debaryomyces, Candida, Pichia, Saccharomyces and Torulopsis. Among the 41 acid-producing strains, mutant strain Yarrowia lipolytica N15 was selected since it was able to produce citric acid presumably in high amounts. The citric acid production by the selected strain was studied in dependence on the medium pH, aeration and concentration of glycerol. Under optimal conditions, the mutant Y. lipolytica N15 produced up to 98 g/L of citric acid when grown in a fermentor with the medium containing pure glycerol, and 71 g/L of citric acid when grown on glycerol-containing waste. The effect of growth phases on physiological peculiarities of the citric acid producer was discussed

Sinteza sukcinske kiseline s pomoću kvasaca uzgojenih na podlozi s etanolom

The synthesis of succinic acid in ethanol-containing media has been tested in 32 yeasts of different genera (Debaryomyces, Candida, Pichia, Saccharomyces, Torulopsis). The capability of succinic acid synthesis was revealed in 29 strains, from which two most effective producers were selected. When grown in a fermentor under high aeration in mineral medium with pulsed addition of ethanol, the strain Candida catenulata VKM Y-5 produced succinic acid up to 5.2 g/L with mass yield of 32.6 % and energy yield of 14.8 %; the other strain, Candida zeylanoides VKM Y-2324, excreted 9.4 g/L of succinic acid with mass and energy yields of 39 and 17.8 %, respectively. It was indicated that succinic acid formation in the yeasts was accompanied by the synthesis of considerable amounts of malic acid, which was apparently due to a high activity of the glyoxylate cycle. Growth characteristics of both strains were studied in dependence on the concentrations of ethanol, zinc ions and nitrogen in the medium.Ispitana je sinteza sukcinske kiseline s pomoću 32 vrste kvasaca različitih rodova (Debaryomyces, Candida, Pichia, Saccharomyces i Torulopsis), uzgojenih na podlozi s etanolom. Otkriveno je da 29 vrsta ima sposobnost sinteze sukcinske kiseline, od kojih su izdvojene dvije najučinkovitije. Uzgojem na podlozi s mineralnim tvarima, u bioreaktoru s pojačanom aeracijom uz dodatak etanola, soj Candida catenulata VKM Y-5 proizveo je 5,2 g/L sukcinske kiseline, s masenim iskorištenjem od 32,6 % i energetskim od 14,8 %, a soj Candida zeylanoides VKM Y-2324 izlučio je 9,4 g/L sukcinske kiseline, s masenim iskorištenjem od 39 % i energetskim od 17,8 %. Utvrđeno je da uz sukcinsku kiselinu nastaje znatna količina malonske kiseline, vjerojatno zbog veće aktivnosti enzima koji sudjeluju u glioksilatnom ciklusu. Ispitane su značajke rasta oba soja ovisno o koncentraciji etanola, cinkovih iona i dušika u podlozi