Enzymic synthesis ofL-Lysine fromDL-α-Amino-ε-caprolactam by new microbial strains

The production of L-lysine fromDL-α-amino-ε-caprolactam (DL-ACL) by new strains producingL-α-amino-ε-caprolactamase and aminocaprolactam racemase is described. Optimal conditions for hydrolysis ofL-ACL byCryptococcus sp. and for racemization of ACL by cells of a strain isolated in nature and identified asPseudomonas sp. were determined. Synthesis ofL-α-amino-ε-caprolactamase is induced byDL-ACL orL-lysine with the same effectivity. A positive effect of phosphates (potassium salts) on reduction of the induction lag was detected, the synthesis of this enzyme was found to be repressed by glucose and some possibilities of the reversion of this repressive effect were demonstrated. Under conditions optimal for the production of both enzymes a quantitative theoretical conversion of 10 % aqueousDL-ACL toL-lysine by a mixture of native cells in a mass ratio of 1: 2 (producer of ACL-hydrolase to producer of ACL-racemase) occurred in 8 h at 40 °C and pH 8.0     

Penicillinamidohydrolase inEscherichia coli

Substrate specificity of the bacterial penicillinamidohydrolase (penicillinacylase, EC 3.5.1.11) fromEscherichia coli was determined by measuring initial rates of enzyme hydrolysis of different substrates within zero order kinetics. SomeN-phenylacetyl derivatives of amino acids and amides of phenylacetic acid and phenoxyacetic acid of different substituted amides of these acids or amides, structurally and chemically similar to these compounds, served as substrates. Significant differences in ratios of initial Tates of the enzyme hydrolysis of different substrates were found when using a toluenized suspension of bacterial cells or a crude enzyme preparation, in spite of the fact that the enzyme is localized between the cell wall and cytoplasmic membrane, in the so-called periplasmic space.N-phenylacetyl derivatives are the most rapidly hydrolyzed substrates. Beta-phenylpropionamide and 4-phenylbutyramide were not utilized as substrates. The substrate specificity of the enzyme is discussed with respect to a possible use of certain colourless compounds as substrates, hydrolysis of which yields chromophor products suitable for a simple and rapid assay of the enzyme activity.     

Which Factors Affect the Success or Failure of Eradication Campaigns against Alien Species?

Although issues related to the management of invasive alien species are receiving increasing attention, little is known about which factors affect the likelihood of success of management measures. We applied two data mining techniques, classification trees and boosted trees, to identify factors that relate to the success of management campaigns aimed at eradicating invasive alien invertebrates, plants and plant pathogens. We assembled a dataset of 173 different eradication campaigns against 94 species worldwide, about a half of which (50.9%) were successful. Eradications in man-made habitats, greenhouses in particular, were more likely to succeed than those in (semi-)natural habitats. In man-made habitats the probability of success was generally high in Australasia, while in Europe and the Americas it was higher for local infestations that are easier to deal with, and for international campaigns that are likely to profit from cross-border cooperation. In (semi-) natural habitats, eradication campaigns were more likely to succeed for plants introduced as an ornamental and escaped from cultivation prior to invasion. Averaging out all other factors in boosted trees, pathogens, bacteria and viruses were most, and fungi the least likely to be eradicated; for plants and invertebrates the probability was intermediate. Our analysis indicates that initiating the campaign before the extent of infestation reaches the critical threshold, starting to eradicate within the first four years since the problem has been noticed, paying special attention to species introduced by the cultivation pathway, and applying sanitary measures can substantially increase the probability of eradication success. Our investigations also revealed that information on socioeconomic factors, which are often considered to be crucial for eradication success, is rarely available, and thus their relative importance cannot be evaluated. Future campaigns should carefully document socioeconomic factors to enable tests of their importance.     

Immobilization of the cellulolytic fungus Trichoderma reesei on the polymeric sorbent - Sorfix

Summary The immobilization of T. reesei mycelium on activated polymeric sorbent was investigated with respect to the intended flow-trough cellulase production. The retention of extracellular production of cellulolytic enzymes was monitored in a packed-column recycle reactor. Some factors affecting cellulase elution pattern are described.     

Azido analogs of neuroactive steroids

Analogs of pregnanolone (3α-hydroxy-5β-pregnan-20-one), modified in position 17 were prepared. Compounds with 20-keto pregnane side chain replaced completely by azide (17α- and 17β-azido-5β-androstan-3α-ol), compounds with its part replaced (20-azido-21-nor-5β-pregnan-3α-ol), and compounds with keto group only replaced ((20R)- and (20S)-20-azido-5β-pregnan-3α-ol) were synthesized using tosylate displacements with sodium azide or Mitsunobu reaction with azoimide. All five azido steroids were converted into corresponding sulfates. Subsequent tests for inhibition of glutamate induced response on NMDA receptors revealed that modification of pregnanolone sulfate side chain with azide did not disturb the activity and some of sulfates tested were more active than parent compound.     

Genetic differentiation of Rubus chamaemorus populations in the Czech Republic and Norway after the last glacial period

The population structure of cloudberry (Rubus chamaemorus L.), collected from Krkonose Mountains (the Czech Republic), continental Norway and Spitsbergen, was examined using microsatellite analyses (SSR). Among 184 individuals, 162 different genotypes were identified. The overall unbiased gene diversity was high (). A high level of genetic differentiation among populations (F_ST = 0.45; p < .01) indicated restricted gene flow between populations. Using a Bayesian approach, six clusters were found which represented the genetic structure of the studied cloudberry populations. The value of correlation index between genetic and geographical distances (r = .44) indicates that gene flow, even over a long distance, could exist. An exact test of population differentiation showed that Rubus chamaemorus populations from regions (Krkonose Mountains, continental Norway and Spitsbergen) are differentiated although some individuals within populations share common alleles even among regions. These results were confirmed by AMOVA, where the highest level of diversity was found within populations (70.8%). There was no difference between 87 pairs of populations (18.7%) mostly within cloudberry populations from continental Norway and from Spitsbergen. Based on obtained results, it is possible to conclude that Czech and Norwegian cloudberry populations are undergoing differentiation, which preserves unique allele compositions most likely from original populations during the last glaciation period. This knowledge will be important for the creation and continuation of in situ and ex situ conservation of cloudberry populations within these areas.