Biosynthesis of naphthoquinone pigments by fungi of the genus Fusarium

We studied biosynthesis of colored naphthoquinone metabolites by Fusarium decemcellulare, F. graminearum, and F. bulbigenum fungi. F. bulbigenum and F. graminearum synthesized bikaverin and aurofusarin, respectively, which depended on the conditions of cultivation. F. decemcellulare synthesized soluble extracellular naphthoquinones of the naphthazarin structure (javanicin, anhydrojavanicin, fusarubin, anhydrofusarubin, bostricoidin, and novarubin) or extracellular dimeric naphthoquinone aurofusarin. Biosynthesis of naphthoquinone pigments was shown to be the main fungal response to stress exposure. It occurs under conditions of growth inhibition or arrest.     

Occurrence of nonmevalonate and mevalonate pathways for isoprenoid biosynthesis in bacteria of different taxonomic groups

The effect of fosmidomycin and mevinoline, inhibitors of the nonmevalonate and the mevalonate pathways of isoprenoid biosynthesis, respectively, on the growth of 34 anaerobic and 10 aerobic prokaryotic strains was studied. Fosmidomycin at the concentrations used was shown to inhibit the growth of 9 (of 10) representatives of the family Microbacteriaceae, 4 (of 5) strains of Thermoanaerobacter, and 11 (of 12) strains of Clostridium, whereas mevinoline inhibited the growth of lactobacilli (Carnobacterium), methanogenic and sulfate-reducing bacteria insensitive to fosmidomycin. During the late growth phase, four strains of actinobacteria (of nine) accumulated the compound, which, upon oxidation, generates a long-lived free radical; three strains synthesized 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC). It was concluded that the difference in the sensitivity of the organisms to fosmidomycin and mevinoline might serve as a test to differentiate several representatives of the family Microbacteriaceae. The use of mevinoline for inhibiting methanogens in ecological investigations seems to be promising.__________Translated from Mikrobiologiya, Vol. 74, No. 2, 2005, pp. 185–190.Original Russian Text Copyright © 2005 by Trutko, Dorofeeva, Shcherbakova, Chuvilskaya, Laurinavichus, Binyukov, Ostrovskii, Hintz, Wiesner, Jomaa, Akimenko.     

Prevalence of nonmevalonate and mevalonate pathways for isoprenoid biosynthesis among bacteria of different systematic groups

The effect of fosmidomycin and mevinoline, inhibitors of the nonmevalonate and the mevalonate pathway of isoprenoid biosynthesis, respectively, on the growth of 34 anaerobic and 10 aerobic prokaryotic strains was studied. Fosmidomycin at the concentrations used was shown to inhibit the growth of 9 (of 10) representatives of the family Microbacteriaceae, 4 (of 5) strains of Thermoanaerobacter, and 11 (of 12) strains of Clostridium, whereas mevinoline inhibited the growth of lactobacilli (Carnobacterium), methanogenic and sulfate-reducing bacteria insensitive to fosmidomycin. During the late growth phase, four strains of actinobacteria (of nine) accumulate the compound, which, upon oxidation, generates a long-lived free radical; three strains synthesize 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC). It was concluded that the difference in the sensitivity of the organisms to fosmidomycin and mevinoline might serve as a test to differentiate several representatives of the family Microbacteriaceae. The use of mevinoline for inhibiting methanogens in ecological investigations seems to be promising.     

Ray-interray interactions during fin regeneration of Danio rerio

Teleost fin ray bifurcations are characteristic of each ray in each fin of the fishes. Control of the positioning of such morphological markers is not well understood. We present evidence suggesting that the interray blastema is necessary for a proper bifurcation of each ray during regeneration in Danio rerio (Hamilton-Buchanan) (Cyprinidae, Teleostei). We performed single ray ablations, heterotopical graftings of ray fragments and small holes in lateral rays which do not normally bifurcate, to generate recombinants in which the lateral rays are surrounded with ectopic interrays originating from different positions within the tail fin. These ray-interray recombinants do now bifurcate. Furthermore, we show that the interray tissue and surrounding epidermis can modulate the length of the ray. These results stress the role of the interray in inducing bifurcations of the ray blastema as well as modulating ray morphogenesis in general. In addition, gene expression analysis under these experimental conditions suggests that msxA and msxD expression in the ray and interray epidermis is controlled by the ray blastema and that bmp4 could be a candidate signal involved in these inductions.     

Methanogenic sarcina from an anaerobic microbial community degrading p-toluene sulfonate

The methanogenic strain MM isolated from an anaerobic microbial community degrading p-toluene sulfonate showed optimal values of temperature and pH for growth equal to 37 degrees C and 6.3-6.9, respectively. The doubling times of the isolate grown on methanol, acetate, and methylamines under the optimal conditions were 8.8, 19.1, and 10.3-28.1 h, respectively. The growth of strain MM was observed only when the cultivation medium contained casamino acids or p-toluene sulfonate. The G + C content of the DNA of the isolate was 40.3 mol%. This, together with DNA-DNA hybridization data, allowed the new isolate to be identified as a strain of the species Methanosarcina mazei. The new isolate differed from the known representatives of this species in that it was resistant to alkylbenzene sulfonates and able to demethylate p-toluene sulfonate when grown on acetate.     

Biosynthesis of somatotropin in a recombinant strain of Escherichia coli

A recombinant Escherichia coli K-12 strain was grown in the regime of chemostat with glucose limitation at a different flow rate and in the regime of turbidostat. The stability of its population and the dynamics of somatotropin biosynthesis were studied. The plasmid-containing strain became less stable as the flow rate in the fermenter dropped down, which was due, apparently, to a greater limitation. The level of somatotropin biosynthesis was higher at a low dilution rate (D = 0.075, 0.17 and 0.34 h-1). Possible factors responsible for this phenomenon are discussed.     

Influence of antibiotics (benzylpenicillin,pharmazin, and nystatin) on the number of microorganisms in ordinary chernozem

In model experiments, the influence of pharmaceutical antibiotics (benzylpenicillin, pharmazin, and nystatin) in different doses (100, 300, 450, and 600 mg/kg) on a number of microorganisms of the chernozem region has been studied. All the studied doses of antibiotics had reliable and overwhelming impacts on the amount of soil microorganisms. The time between a dose of antibiotics and a change in the number of microorganisms in the soil is shown to have a linear dependence. The studied groups of soil microorganisms in relation to pharmaceutical antibiotics showed a hierarchy of resistance (high concentration): Azotobacter > amylolytic bacteria > ammonifying bacteria > micromycetes.     

Redox reactions in hydrocortisone transformation by Arthrobacter globiformis cells

Hydrocortisone and prednisolone transformation by Arthrobacter globiformis cells in aerobic and anaerobic conditions was studied. 3-Ketosteroid-1-en-dehydrogenase activity was shown to be the major factor regulating the direction of transformation. When it is high (aerobic conditions), the end products of hydrocortisone transformation are prednisolone or its 20 beta-hydroxy derivative. The latter is produced via 1-en-dehydrogenation, which is not a limiting stage of the process. Low 3-ketosteroid-1-en-dehydrogenase activity (in the presence of cyanide) or its complete inhibition (strictly anaerobic conditions) result in the direct reduction of 20-keto group of hydrocortisone.     

Cause of the activity loss of the alternative pathway of electron transport in cyanide-resistant mitochondria of the yeast Candida lipolytica

The cause of the activity loss of alternative pathway of electron transport in mitochondria of the yeast Candida lipolytica has been investigated. Incubation of cyanide-resistant mitochondria at 25 degrees was shown to cause the loss by mitochondria of their ability to oxidize substrates in the presence of 1 mM cyanide. This suggests that in the course of incubation the alternative pathway loses its activity. Repeated washing of mitochondria with a solution containing 2,5 mM EDTA inhibits, while Ca2+, Mn2+, Cu2+ and Zn2+ (but not Sr2+) enhance the process of the activity loss of the alternative pathway. The loss of the cyanide-resistant respiration is also observed during incubation of mitochondria in the presence of phospholipases A, C and D or lysolecithin. In all cases studied the reactivation of the cyanide-resistant respiration of mitochondria is attained by addition of azolectin. The loss of cyanide-resistant respiration is accompanied by the activity reduction of the main respiratory chain, which is restored by addition of cytochrome c and Mg2+. These data indicate that the activity loss of the alternative pathway is not related to inactivation of any components in the alternative pathway itself or in the main respiratory chain. The most probable cause of the activity loss in the destruction of reducing equivalents in the alternative pathway of a donor as a result of a break of the structural entity of the internal membrane of mitochondria due to the detersive action of the phospholipid lysoforms produced either by endogenic or exogenic phospholipases.