Degradation of long-chain n-alkanes by mucorales

Summary The composition of fatty acids in the lipids ofAbsidia spinosa, Cunninghamella echinulata, andMortierella isabellina was determined after growth on glucose and some n-alkanes. Mycelia metabolizing odd-carbon n-alkanes contained, among others, mono- and polyenoic heptadecanoic acids, that is, C_17:1(9)-, C_{17:2(9, 12)}-, and C_{17:3(6, 9, 12)}-acids. From the amounts of the isolated lipids it can be deduced thatAbsidia andCunninghamella may mainly degrade the alkanes in a terminal oxidation pathway whileMortierella prefers a subterminal way.Dedicated to Professor Dr. L. Acker on the occasion of his 65th birthday     

Degradation of long chain n-alkanes by mucorales

Summary Extracellular oxidation products isolated from the substrates ofMortierella isabellina (CBS 224. 35) grown on n-dodecane and n-tridecane were primary and secondary isomeric alcohols, isomeric ketones, aldehydes and isomeric esters with the same numbers of carbon atoms presented in the used n-alkanes as detected by combined glass capillary gas chromatography — mass spectrometry. All esters were identified which theoretically could originate in the isomeric ketones by a reaction mechanism resembling a Baeyer-Villinger-type oxidation.     

The utilization of the mixtures of monosaccharides by some mucorales

Summary The utilization of mixtures of monosaccharides byBlakeslea trispora Thaxter,Choanephora circinans (Naganish &Kawakami)Hesseltine &Benjamin,Gilbertella persicaria var.indica Mehrotra &Mehrotra andHelicostylum piriforme Bainier was studied. The effect of sorbose on the utilization of other sugars present in the mixtures was also studied. It was found that all the mixtures of sugars in combination with asparagine or ammonium chloride were valueless for all the organisms exceptHelicostylum piriforme. Growth ofHelicostylum piriforme on the mixtures with asparagine as the nitrogen source was better than on the mixtures with ammonium chloride as the source of nitrogen. Asparagine being a favourable source counteractecd sorbose inhibition, while ammonium chloride failed to do so. On the other hand, both of the nitrogen sources failed to counteract sorbose inhibition in the rest of the organisms. None of the organisms could finish sorbose and rhamnose from any of the mixtures within the specified period.     

Structure and function of the genes involved in the biosynthesis of carotenoids in the mucorales

Carotenoids are widely distributed natural pigments which are in an increasing demand by the market, due to their applications in the human food, animal feed, cosmetics, and pharmaceutical industries. Although more than 600 carotenoids have been identified in nature, only a few are industrially important (β-carotene, astaxanthin, lutein or lycopene). To date chemical processes manufacture most of the carotenoid production, but the interest for carotenoids of biological origin is growing since there is an increased public concern over the safety of artificial food colorants. Although much interest and effort has been devoted to the use of biological sources for industrially important carotenoids, only the production of biological β-carotene and astaxanthin has been reported. Among fungi, several Mucorales strains, particularlyBlakeslea trispora, have been used to develop fermentation process for the production of β-carotene on almost competitive cost-price levels. Similarly, the basidiomycetous yeastXanthophyllomyces dendrorhous (the perfect state ofPhaffia rhodozyma), has been proposed as a promising source of astaxanthin. This paper focuses on recent findings on the fungal pathways for carotenoid production, especially the structure and function of the genes involved in the biosynthesis of carotenoids in the Mucorales. An outlook of the possibilities of an increased industrial production of carotenoids, based on metabolic engineering of fungi for carotenoid content and composition, is also discussed.     

Localization and partial characterization of a sex-specific enzyme in homothallic and heterothallic mucorales

A study was made of some late reactions in the trisporic acid biosynthetic pathway in Mucor mucedo. Trisporic acids induce sexual reproduction in several Mucorales.Two enzymes involved in these reactions, a NADP-dependent dehydrogenase and an esterase, appeared to be highly specific for the minus mating type.The synthesis of these enzymes is stimulated by trisporic acids, indicating a positive control of these hormones upon their own synthesis.The dehydrogenase was histochemically shown to be concentrated in the zygophores of Mucor mucedominus. In the homothallic Zygorhynchus moelleri the copulating main branch (which is known to have a minus character) appeared to be the major site of dehydrogenase activity.     

Sexuality and reproduction

The relationship between coital rates, a quantitative index of sexuality, and the quality and quantity of reproduction is discussed in terms of sex ratio, delayed fertilization, frequency of intercourse, intercourse distribution within the menstrual cycle, acceleration of ovulation, and the quality of intercourse. Frequency of intercourse affects chances of conception, but its effect on twinning and sex ratio are unclear. Current research on reproduction offers little evidence of the effect of intercourse quality on reproduction in fully fecund individuals; research into the possible effect on reduced fecundity would be desirable.     

Perspectives on Human Sexuality

Perspectives on Human Sexuality. Anne Bolin and Patricia Whelehan. Albany: State University of New York Press. 1999. 503 pp.