Oxidation and amidation of salicylate by Streptomyces species

Seven streptomycete strains were tested for biotransformation of salicylate. The products were identified by nuclear magnetic resonance spectroscopy and three types of conversion were found. Streptomyces cinnamonensis and Streptomyces spectabilis formed gentisate and salicylamide concurrently. Streptomyces rimosus transformed salicylate to salicylamide. Streptomyces lividans, Streptomyces coelicolor, Streptomyces griseus and Streptomyces avermitilis produced only gentisate. Time course studies of salicylate conversion by thin-layer chromatography and high pressure liquid chromatography showed that salicylamide was accumulated in the culture broth, whereas gentisate was further metabolized.Key words: salicylate, gentisate, salicylamide, biotransformation, Streptomyces spp.     

Variance deficit is not reliable evidence for niche limitation

Variance deficit in the number of species per sampling unit, as compared to a null model with species occurring independently of each other has been considered by various authors to be evidence for niche limitation. I show that simpler mechanisms could explain this phenomenon. Of those, the competition of individuals for space limits the number of individuals per sampling unit, resulting in decrease of variance in species richness. Testing the proportions of species belonging to various guilds seems to be more ecologically interesting, although here also the variance deficit can hardly be taken as reliable evidence for niche limitation.     

The growth form of the inducing microorganism and chitin addition affect mycolytic enzyme production byTrichoderma harzianum

The effect of the growth form of the inducing microorganism on specificTrichoderma harzianum mycolytic enzyme production was studied. The pelleted form ofRhizopus nigricans gave a better product concerning protoplast formation ability. The maximum yield of protoplasts from the target fungusCochliobolus lunatus was 1×10⁸ ml^–1. Analysis of individual specific enzyme activities inTrichoderma mycolytic enzyme preparations confirms the importance of high chitinase and low protease activity for high protoplast yields. Supplementation of the production medium with chitin increased the chitinase activity in theTrichoderma exoenzyme mixture.     

Organization of telomeric and subtelomeric chromatin in the higher plant Nicotiana tabacum

We have examined the structure and chromatin organization of telomeres in Nicotiana tabacum. In tobacco the blocks of simple telomeric repeats (TTTAGGG)_n are many times larger than in other plants, e.g., Arabidopsis thatiana or tomato. They are resolved as multiple fragments 60–160 kb in size (in most cases 90–130 kb) on pulsed-field gel electrophoresis (PFGE) of restriction endonuclease-digested DNA. The major subtelomeric repeat of the HRS60 family forms large homogeneous blocks of a basic 180 by motif having comparable lengths. Micrococcal nuclease (MNase) cleaves tobacco telomeric chromatin into subunits with a short repeat length of 157±5 bp; the subtelomeric heterochromatin characterized by tandemly repeated sequences of the HRS60 family is cut by MNase with a 180 by periodicity. The monomeric and dimeric particles of telomeric and subtelomeric chromatin differ in sensitivity to MNase treatment: the telomeric particles are readily digested, producing ladders with a periodicity of 7 bp, while the subtelomeric particles appear to be rather resistant to intranucleosomal cleavage. The results presented show apparent similarities in the organization of telomeric chromatin in higher plants and mammals.     

Thermodynamics of denaturation of α-chymotrypsinogen A in aqueous urea and alkylurea solutions

The effects of pH, urea, and alkylureas on the thermal stability ofα-chymotrypsinogen A (α-ctg A) have been investigated by differential scanning calorimetry (DSC) and UV spectroscopy. Heat capacity changes and enthalpies of transition ofα-ctg A in the presence of urea and alkylureas were measured at the transition temperature. Using these data, the corresponding Gibbs free energies, enthalpies, and entropies of denaturation at 25°C were calculated. Comparison of these values shows that at 25°C denaturation with urea is characterized by a significantly smaller enthalpy and entropy of denaturation. At all denaturant concentrations the enthalpy term slightly dominates the entropy term in the Gibbs free energy function. The most obvious effect of alkylureas was lowering of the temperature of transition, which was increasing with alkylurea concentration and the size of alkyl chain. Destabilization of the folded protein in the presence of alkylureas appears to be primarily the result of the weakening of hydrophobic interactions due to diminished solvent ordering around the protein molecules. At pH lower than 2.0,α-ctg A still exists in a very stable form, probably the acid-denatured form (A-form).     

Transfer of the broad-host-range IncQ plasmid RSF1010 and other plasmid vectors to the Gram-positive methylotroph Brevibacterium methylicum by electrotransformation

Gram-positive facultative methylotrophic coryneform bacterium Brevibacterium methylicum was efficiently transformed with various plasmids using electroporation of intact cells. In addition to the plasmid vectors pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from coryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasmid pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to be present as autonomous structurally unchanged DNA molecules in B. methylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selective conditions. When plasmid DNAs isolated from B. methylicum were used, the highest efficiency of transformation (10⁵ transformants/g DNA) was achieved. Correspondence to: J. Nevera     

Correlation between physico-chemical properties of quaternary ammonium salts of heptacaine and their inhibitory activity against photosynthesizing organisms

Photosynthesis inhibition in algae (Chlorella) and plant (spinach) chloroplasts by quaternary ammonium salts of heptacaine {N-[2-(2-heptyloxyphenylcarbamoyloxy)-ethyl]-N-alkylpiperidinium bromides} depended on the alkyl chain length of the alkyl substituent and showed good correlations with theoretical hydrophobic fragment constants as well as with experimentally determined physico-chemical parameters, namely extraction constants and surface activities. Communicated by. Z. ŠESTáK     

Inhibitory effect of lignin by-products of pulping on yeast growth

The antimicrobial properties of lignin by-products obtained by organic solvent, neutral sulfite semichemical and kraft pulping were shown in a series of yeasts. Lignin can act as an inhibitor of growth ofSporobolomyces roseus, Candida tropicalis, Trichosporon cutaneum andCandida albicans. Oxidation of all lignin samples tested depresses their inhibitory effects.     

Application of the exploratory data analysis for evaluating the toxicity of chlorinated phenol derivatives by various cell models

Exploratory data analysis based on multivariate statistical analysis techniques was introduced as a new approach to expressing the toxicity of chemical substances at the simultaneous acceptance of various cell models. Using principal component analysis and cluster analysis methods the toxicity of chlorinated phenol derivatives on employing some of the cell models (chlorococcal algae, cyanobacteria, bacteria, micromycetes, plant and animal cells) was characterized. The previous empirical experience that the toxicity of chlorinated phenol derivatives will increase with a growing degree of chlorination and that the presence of the methoxy group will cause a lowering of the toxic effect was demonstrated. The relationship between groups of tests used was presented.