Search

The enzymatic hydrolysis of lignocellulosic material in nature is carried out by a plethora of cellulases. Glycoside hydrolase family 45 (GH45) enzymes are small cellulases most commonly found in fungi that catalyse the hydrolysis of β(1→4) linked glucans. Additionally, GH45 enzymes display a structural resemblance to non-hydrolytic protein groups such as expansins and loosenins. In this thesis, the distinctness of GH45 enzymes from different subfamilies was explored. The enzymatic activity of GH45 enzymes from Humicola insolens (HiCel45A), Mytilus edulis (MeCel45A), Trichoderma reesei (TrCel45A), Phanerochaete chrysosporium (PcCel45A), Gloeophyllum trabeum (GtCel45A) was demonstrated. Among the tested substrates were barley betaglucan, konjac glucomannan, carboxymethyl cellulose, and cellohexaose. Initial hydrolysis rates and hydrolysis yields were determined by reducing sugar assays, product formation was analysed using NMR spectroscopy and HPLC. The subfamily B and C enzymes exhibited mannanase activity, and the subfamily B enzyme MeCel45A appeared cold adapted in comparison to TrCel45A. GH45 enzymes are known to act using an inverting action mechanism. This action mechanism had not been experimentally demonstrated in subfamilies B and C, however. Here experimental evidence is provided for the inverting nature of GH45 enzymes from all subfamilies.Comparisons of GH45 enzyme structures were carried out and the first crystal structure of a GH45 subfamily C enzyme from the brown-rot fungus G. trabeum was reported at 1.3 Å resolution. Furthermore, structure and function investigations were done on an isotopically labelled Cel45A from the white-rot fungus P. chrysosporium using NMR spectroscopy. PcCel45A was expressed in Pichia pastoris with 13C and 15N labelling. A nearly complete assignment of 1 H, 13C and 15N backbone resonances was obtained and the interaction of 15Nlabelled PcCel45A with cellobiose was studied.

Ik gadu LR normatīvajos aktos veic izmaiņas. 2018. gadā paredzētas izmaiņas darba samaksas aprēķinos. Darba mērķis ir, pamatojoties uz normatīvo aktu un speciālās literatūras izpēti, noskaidrot, kuram šīs normatīvo aktu izmaiņas ir izdevīgas. Mērķa sasniegšanai noteikti uzdevumi: •Noskaidrot, kas ir darba samaksa un kādi nodokļi ar to saistīti; •Izpētīt 2017.gada normatīvos aktus un izanalizēt, kādas izmaiņas gaidāmas 2018. gadā saistībā ar darba samaksas aprēķināšanu; •Noskaidrot, ar kādām izmaiņām jārēķinās katrai iesaistītajai pusei 2018. gadā; •Izdarīt secinājumus par veiktajiem pētījumiem. Pētījuma veikšanā izmantoti LR normatīvie akti un uzņēmuma dokumenti. Pētījumā tiek izmantotas matemātiskās, kontentanalīzes un salīdzinošās metodes. Darbs sastāv no 66 lapām, tas ietver 4 attēlus un 17 tabulas., Every year are changes in the laws of the Republic of Latvia. In 2018, changes will be made to payroll calculations. The aim of the work is to find out, on the basis of study of normative acts and special literature, which changes in these normative acts are beneficial. Objectives: •Find out what salaries are and what taxes are involved with it; •Examine the laws of 2017 and analyse what changes are expected in 2018 in relation to the calculation of wages; •Find out what changes should be made by each of the parties involved in 2018; •Make conclusions about the research done. The research used LR normative acts and company documents. The study uses mathematical, contingent analysis and comparative methods. The work consists of 66 pages; it includes 4 pictures and 17 tables.

Darbā novērtēta lignocelulozi saturošu piedevu (kļavu lapas, dažādi apstrādāti kviešu salmi) ietekme uz L. edodes 3565 micēlija biomasas pieaugumu un ekstracelulārās lakāzes aktivitāti. Augstākā lakāzes aktivitāte (545.74±135.92 U/mL) un lielākais micēlija biomasas guvums (422.92±31.52 mg/100 mL) iegūts šķidrās iesala ekstrakta barotnēs ar hemicelulozi un celulozi nesaturošu kviešu salmu piedevu (0.50%), inkubējot uz rotācijas kratītāja (140 rpm). Inkubācijas laikā novērots: 1) pakāpenisks lakāzes aktivitātes pieaugums neatkarīgi no piedevas; 2) vides pH samazināšanās. Maltas kļavu lapas novērtētas kā micēlija blīvumu un radiālo augšanu veicinoša piedeva neatkarīgi no pamatbarotnes. Maltas brūnaļģes novērtētas kā barotni bagātinoša piedeva agarizētās iesala ekstrakta barotnēs. Novērota kultivēšanas temperatūras ietekme uz lakāzes aktivitāti un micēlija biomasas pieaugumu., Effect of lignocellulose additives (wheat straw, maple leaves) on extracellular laccase activity and mycelium yield was evaluated. Highest laccase activity (545.74±135.92 U/mL) and mycelium yield (422.92±31.52 mg/100 mL) was obtained in malt extract on rotatory shaker (140 rpm) cultures with wheat straw additive (0.50%) which did not contain hemicellulose and cellulose. The following observations were made during the cultivation period: 1) laccase activity gradually rises independently of additives; 2) pH of the medium decreases. Ground maple leaves facilitated an increase in mycelium density and radial growth regardless of medium. Seaweed showed to be medium enriching additive on solid malt extract medium. The influence of temperature on laccase activity and mycelium yield was observed.

Darbā pētīta Lentinula edodes micēlija augšana lignīnu saturošās barotnēs, kas novērota piecos eksperimentos uz agarizētām barotnēm un trijos eksperimentos, inkubējot šķidrās barotnēs. Inkubācija +22°C, uz cietām barotnēm līdz 16 dienām, šķidrajās barotnēs līdz 28 dienām. Pārbaudīta lignīna koncentrācijas, lignīnu saturošā materiāla apstrādes ietekme uz micēlija augšanas ātrumu, salīdzinošo blīvumu, morfoloģiju un lakkāzes aktivitāti. Novērota komerciālā lignīna koncentrācijas 0.05% un 0.25% diametrālo augšanu veicinoša ietekme uz micēliju šķidrajās barotnēs. Novērota hidrolizētas lignocelulozes veicinoša ietekme uz micēlija diametra augšanu agarizētajās barotnēs. Lignocelulozi saturošajās šķidrajās barotnēs novērota lielākā lakkāzes aktivitāte. Darbs izstrādāts LU Bioloģijas fakultātes Mikrobioloģijas un biotehnoloģijas katedrā, Dr. biol., doc. Nataļjas Matjuškovas vadībā. Daļa darba izstrādāta LU Mikrobioloģijas un biotehnoloģijas institūtā, Dr. biol., doc. Nataļjas Matjuškovas vadībā., Effect of lignin containing environment on Lentinula edodes mycelial growth was studied in this work. Five experiments on solid media and three experiments in liquid media were carried out. Growth at +22°C on solid media was monitored for 16 days, in liquid media – 28 days. Effect of lignin concentration and pre-treatment of lignocellulosic material on mycelial growth, it’s density, morphology and produced laccase activity was observed. Results showed commercial lignin concentrations 0.05% and 0.25% to have mycelial diametric growth promoting effect in liquid media. Hydrolysed lignocelullosic material improved diametric growth of mycelia in solid media. Liquid media containing lignocellulose showed the highest laccase activity. Bachelor’s work was developed in University of Lavia, Faculty of Biology and Biotechnology, in lead of Dr. biol., doc. Nataļja Matjuškova. Part of this work was developed in Institute of Microbiology and Biotechnology, University of Latvia, in lead of Dr. biol., doc. Nataļja Matjuškova.