Differentiation Between Amino Acids Used as Carbon and Energy Sources During Growth of Geotrichum candidum Geo17

Geotrichum candidum Geo17 was cultivated on peptones as carbon and nitrogen source, and in the presence of lactate as the second carbon source. From the analysis of the initial and final culture medium after total hydrolysis, the yield of consumption was determined for each amino acid. Amino acids have been considered a convenient carbon source for biosynthesis, while the rest of the amino acids were assumed to be used only as a nitrogen source, with the corresponding carbon released as CO2 resulting from energy supply. Carbon mass balances confirmed this assumption. A clear differentiation between the amino acids assimilated as carbon sources and those assimilated as energy sources was therefore highlighted

Pregled bioloških metoda ekstrakcije hitina iz oklopa rakova

After cellulose, chitin is the most widespread biopolymer in nature. Chitin and its derivatives have great economic value because of their biological activities and their industrial and biomedical applications. It can be extracted from three sources, namely crustaceans, insects and microorganisms. However, the main commercial sources of chitin are shells of crustaceans such as shrimps, crabs, lobsters and krill that are supplied in large quantities by the shellfish processing industries. Extraction of chitin involves two steps, demineralisation and deproteinisation, which can be conducted by two methods, chemical or biological. The chemical method requires the use of acids and bases, while the biological method involves microorganisms. Although lactic acid bacteria are mainly applied, other microbial species including proteolytic bacteria have also been successfully implemented, as well as mixed cultures involving lactic acid-producing bacteria and proteolytic microorganisms. The produced lactic acid allows shell demineralisation, since lactic acid reacts with calcium carbonate, the main mineral component, to form calcium lactate.Hitin je, nakon celuloze, najrasprostranjeniji biopolimer u prirodi. Hitin i njegovi derivati imaju veliku ekonomsku vrijednost zbog njihove biološke aktivnosti te moguće primjene u industriji i biomedicini. Može se ekstrahirati iz tri izvora, i to iz rakova, insekata i mikroorganizama. No, glavni komercijalni izvor hitina su oklopi rakova, kao što su škampi, rakovice, jastozi i zooplanktonski (krill) račići, koji u velikim količinama preostaju nakon prerade rakova. Ekstrakcija se hitina odvija u dva koraka: demineralizacija i deproteinizacija, a može se provesti kemijskim ili biološkim putem. Kemijska metoda podrazumijeva uporabu kiselina ili baza, a biološka uključuje primjenu mikroorganizama. Iako se najčešće primjenjuju mliječno-kisele bakterije, dosad su uspješno upotrijebljene i proteolitičke bakterije, te mješovite kulture mliječno-kiselih bakterija i proteolitičkih mikroorganizama. Nastala mliječna kiselina omogućuje daljnju demineralizaciju, jer reagira s kalcijevim karbonatom, glavnim mineralnim sastojkom oklopa, pri čemu nastaje kalcijev laktat

Differentiation Between Amino Acids Used as Carbon and Energy Sources During Growth of Geotrichum candidum Geo17

Geotrichum candidum Geo17 was cultivated on peptones as carbon and nitrogen source, and in the presence of lactate as the second carbon source. From the analysis of the initial and final culture medium after total hydrolysis, the yield of consumption was determined for each amino acid. Amino acids have been considered a convenient carbon source for biosynthesis, while the rest of the amino acids were assumed to be used only as a nitrogen source, with the corresponding carbon released as CO2 resulting from energy supply. Carbon mass balances confirmed this assumption. A clear differentiation between the amino acids assimilated as carbon sources and those assimilated as energy sources was therefore highlighted

Pregled bioloških metoda ekstrakcije hitina iz oklopa rakova

After cellulose, chitin is the most widespread biopolymer in nature. Chitin and its derivatives have great economic value because of their biological activities and their industrial and biomedical applications. It can be extracted from three sources, namely crustaceans, insects and microorganisms. However, the main commercial sources of chitin are shells of crustaceans such as shrimps, crabs, lobsters and krill that are supplied in large quantities by the shellfish processing industries. Extraction of chitin involves two steps, demineralisation and deproteinisation, which can be conducted by two methods, chemical or biological. The chemical method requires the use of acids and bases, while the biological method involves microorganisms. Although lactic acid bacteria are mainly applied, other microbial species including proteolytic bacteria have also been successfully implemented, as well as mixed cultures involving lactic acid-producing bacteria and proteolytic microorganisms. The produced lactic acid allows shell demineralisation, since lactic acid reacts with calcium carbonate, the main mineral component, to form calcium lactate.Hitin je, nakon celuloze, najrasprostranjeniji biopolimer u prirodi. Hitin i njegovi derivati imaju veliku ekonomsku vrijednost zbog njihove biološke aktivnosti te moguće primjene u industriji i biomedicini. Može se ekstrahirati iz tri izvora, i to iz rakova, insekata i mikroorganizama. No, glavni komercijalni izvor hitina su oklopi rakova, kao što su škampi, rakovice, jastozi i zooplanktonski (krill) račići, koji u velikim količinama preostaju nakon prerade rakova. Ekstrakcija se hitina odvija u dva koraka: demineralizacija i deproteinizacija, a može se provesti kemijskim ili biološkim putem. Kemijska metoda podrazumijeva uporabu kiselina ili baza, a biološka uključuje primjenu mikroorganizama. Iako se najčešće primjenjuju mliječno-kisele bakterije, dosad su uspješno upotrijebljene i proteolitičke bakterije, te mješovite kulture mliječno-kiselih bakterija i proteolitičkih mikroorganizama. Nastala mliječna kiselina omogućuje daljnju demineralizaciju, jer reagira s kalcijevim karbonatom, glavnim mineralnim sastojkom oklopa, pri čemu nastaje kalcijev laktat

Cultures pures en bioréacteur de deux microorganismes d'affinage du camembert, penicillium camembertii et géotrichum candidum

L'affinage du camembert est régulé par deux populations fongiques, Geotrichum candidum et Penicillium camembertii. Pour éviter le problème de la mesure de la biomasse à la surface d'un milieu solide, la culture liquide a été préférée. Pour les deux microorganismes, les relations entre cinétique de croissance et cinétiques de consommation ou de production ont été examinées. Les cultures sur milieux à base de peptones ou de glutamate ont montré que le lactate ne convient pas à G. candidum comme source de carbone, il n'est en effet assimilé que comme source d'énergie pour le maintien cellulaire durant la phase stationnaire. Par contre, P. camembertii assimile simultanément lactate et peptones ou glutamate. Cependant, sur glutamate et lactate nous avons mis en évidence un découplage des sources de carbone et d'énergie: le glutamate est assimilé comme source de carbone (et d'azote), et le lactate comme source d'énergie. Un modèle non structuré a été développé pour prédire la croissance microbienne. Le modèle permet également de déduire de la cinétique considérée, les parts respectives liées à la croissance et à la maintenance cellulaire.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Sequential use of ammonium and leucine as nitrogen sources during growth of Geotrichum candidum on a glucose based medium

International audienceGeotrichum candidum growth on ammonium and leucine as nitrogen sources and glucose as a carbon source was examined. A clear preference of G. candidum for ammonium over leucine as a nitrogen source was shown. Indeed, ammonium was completely exhausted at the end of exponential growth after less than 35 hrs of culture; in contrast only 5% of leucine was concomitantly assimilated. Growth continued at slower rates on glucose and leucine as carbon and nitrogen sources respectively, and at the end of culture (185 hrs), leucine was completely exhausted

Chitin Extraction from Crustacean Shells Using Biological Methods – A Review

After cellulose, chitin is the most widespread biopolymer in nature. Chitin and its derivatives have great economic value because of their biological activities and their industrial and biomedical applications. It can be extracted from three sources, namely crustaceans, insects and microorganisms. However, the main commercial sources of chitin are shells of crustaceans such as shrimps, crabs, lobsters and krill that are supplied in large quantities by the shellfish processing industries. Extraction of chitin involves two steps, demineralisation and deproteinisation, which can be conducted by two methods, chemical or biological. The chemical method requires the use of acids and bases, while the biological method involves microorganisms. Although lactic acid bacteria are mainly applied, other microbial species including proteolytic bacteria have also been successfully implemented, as well as mixed cultures involving lactic acid-producing bacteria and proteolytic microorganisms. The produced lactic acid allows shell demineralisation, since lactic acid reacts with calcium carbonate, the main mineral component, to form calcium lactate

Effect of temperature in Chitin and Chitosan production by solid culture of Penicillium Camembertii on YPG medium

International audienc

Optimization of medium composition for enhanced chitin extraction from Parapenaeus longirostris by Lactobacillus helveticus using response surface methodology

International audienceChitin extraction by biological way, using the lactobacilli Lactobacillus helveticus, is a non-polluting method and offers the opportunity to preserve the exceptional qualities of chitin and its derivatives. However, the major disadvantage of the fermentative way is the low efficiency of demineralization and deproteinization. The aim of our study is to improve the yield of extraction. Many factors, such as the initial concentration of carbon source, fermentation time, incubation temperature, inoculum size, shell size, volume and medium composition have been reported to influence the fermentation process and consequently demineralization and deproteinization efficiency. Based on the use of central composite design and response surface methodology ten factors with three levels each were examined to determine the optimal operational conditions of demineralization and deproteinization. The analysis of the obtained results showed that the optimal conditions of 98% of demineralization and 78% of deproteinisation are 171.4 g L−1 of reducing sugars, 2.03 g of nitrogen source [(NH4)2Fe(SO4)2] and 1.29 g of calcium source (CaCl2), used to ferment 4.84 g of shells, of 1.053 mm size heat treated at 120 °C, with 10 mL of inoculum (L. helveticus) incubated at 32.1 °C in 100 mL of juice date for 254.38 h (15 days)