Amylase and cellulase activities of thermophilic fungi causing deterioration of tobacco products in Nigeria

The conditions necessary for the production and activities of extracellular enzymes of thermophilic fungi obtained from tobacco products were determined. While amylases were produced in extractable amounts by all the fungi used in this study, extracellular cellulases were produced only by Chaetomium thermophile La Touche, Humicola insolens Cooney and Emerson, Malbranchea pulchella Sacc. et Penzig var. sulfurea (Miehe) Cooney and Emerson, and Mucor pusillus Lindt. A narrow range of pH 6–7 was best for the activities of the amylases of all the fungi used while a lower range of pH 5–6 was optimal for their cellulase activities. Peak activities were recorded for both enzymes at a temperature range of 45 °–50 °C. The possible use of the exo-enzymes of these fungi in industrial fermentation processes is suggested.     

Biotoxic activity in the Mucorales

The toxigenicity of representatives of 15 species of Mucorales (Absidia glauca, Actinomucor elegans, Cunninghamella elegans, Helicostylum piriforme, Mortierella isabellina, Mortierella (Mucor) rammaniana, Mucor hiemalis, Mucor mucedo, Mucor spinosus, Phycomyces blakesleeanus, Rhizopus oligosporus, Rhizopus stolonifer, Syncephalastrum racemosum, Thamnidium elegans, Zygorhynchus moelleri) towards the larvae of brine shrimp (Artemia salina) and the growth of pea seedlings (Pisum sativum) and tobacco plants (Nicotiana tabacum) was evaluated. The fungi were cultivated on malt extract agar and aqueous solutions of the cultures were tested.Thamnidium elegans showed a marked toxic action towards brine shrimp (mortality: 74.1%) andPhycomyces, Actinomucor andSyncephalastrum were only weakly toxic. Length and weight of stems of pea seedlings were moderately reduced by extracts ofAbsidia, Cunninghamella, Zygorhynchus andThamnidium and to a lesser degree byMucor spinosus. Cunninghamella andMucor spinosus also inhibited the development of pea hypocotyls. The length of tobacco stems was reduced byMortierella ramanniana, Rhizopus stolonifer andCunninghamella elegans. Wilting or other toxic phenomena were never observed with both test plants. Considering the present results and data from literature it is suggested that species of Mucorales have only a weak toxigenicity.     

Thermophilic fungi and applied research: a synopsis of name changes and synonymies

The present synopsis reports on taxonomic decisions and name changes introduced in the last decades for a number of thermophilic fungi. Taxa dealt with are those most commonly cited in the literature of fundamental and applied work or concern species having complex taxonomic histories. The definition of a thermophile follows the classificatory scheme elaborated by Cooney & Emerson in 1964. The synopsis provides the latest legal valid names for several thermophiles. Binomials of accepted synonymies are also reported with arguments in favour of these taxonomic decisions. The material of this contribution is a synthetic simplified account of two previous reviews on the taxonomy of thermophilic fungi. The present document aims: (1) to suppress the use of ghost binomials having no status of any kind; (2) to favour the continuous use of the latest legal valid name of a taxon to avoid cases of redundancies by citing binomials of known synonyms. Homogeneity in cited names is a fundamental prerequisite for comparative studies. The synopsis is thus a sound tool for future critical reviews of ecological and of biotechnological interests. The status of over a hundred names are here reviewed. Two additional new synonyms are proposed; these concern Mucor miehei var. minor and Sporotrichum cellulophilum. This revised version was published online in November 2006 with corrections to the Cover Date.     

Regioselectivity of lipases in organic solvents

Summary A facile system was developed for the quantitative determination of lipase regioselectivities in organic solvents towards the 1(3)-position of glycerides. It was utilized for the measurement of the regioselectivities displayed by lipase preparations fromMucor miehei (Lipozyme),Pseudomonas fluorescens andRhizopus delemar. It was shown that the lipases fromMucor miehei andPseudomonas fluorescens do in fact not display the high 1(3)-specifities reported in the literature for these enzymes.     

Efficient isolation of thermophilic and thermotolerant mucoralean fungi

Rhizomucor miehei (Cooney & Emerson) Schipper, R. pusillus (Lindt) Schipper, Rhizopus rhizopodiformis (Cohn) Zopf, and Absidia corymbifera (Cohn) Sacc. & Trotter were isolated from numerous materials immersed in YpSs agar or 2% malt extract agar containing 50 g/ml Benlate, 100 U/ml penicillin G, and 40 g/ml streptomycin sulfate; agar plates were incubated at 45 °C. Alternative media and procedures useful for special circumstances are described. These four pathogenic thermophilic or thermotolerant species were readily isolated from spices, herbal teas, sunflower seeds, and other materials.     

Production and Purification of Thermostable β-Glucosidase from Mucor miehei YH-10

A thermophilic fungus, Mucor miehei YH-10, isolated from manure was selected to produce thermostable β-glucosidase among 207 isolates. When Mucor miehei YH-10 was grown on wheat bran medium, the maximal accumulation of thermostable β-glucosidase was obtained after 4 days at 50°C, The β-glucosidase had an optimal temperature of 60°C and retained 73% of original activity after heating at 95°C for 5 min. The β-glucosidase was fractionated by Sephadex G-100 chromatography into two components during the purification steps. These components were further purified by consecutive column chromatographies until they were homogeneous on disc electrophoresis. One retained 56% of original activity after heating at 95°C for 5 min, whereas the other was completely inactivated after heating at 80°C for 5 min.     

The effects of fungicides on the growth rates of thermophilous fungi

The effects of the fungicides Captan, Dicloran, Thiram, Verdasan and mercuric chloride (HgCl₂) on the radial and mycelial growth rates of thermophilous fungi isolated from living green leaves were studied. On controlplates Thermoascus aurantiacus andTorula thermophila had the highest radial growth rates whileMalbranchea pulchella var.sulfurea andTalaromyces duponti had the lowest growth rates. Good sporulation was seen on all control plates.With increasing concentrations of fungicides the growth rates were correspondingly retarded and sporulation was reduced. At het higher fungicide concentrations the hyphal tips and young hyphae were thicker and warty or granulated.Of the fungi studies,Aspergillus andMucor pusillus were the most tolerant species; they were capable of growth in more concentrations of fungicides compared with the other species.Talaromyces duponti andThermomyces lanuginosus emerged as the most sensitive species.Most marked reductions in the growth rates were produced by Thiram and Verdasan than by the other fungicides. All the ten thermophilous species studied were capable of growth with more concentrations of HgCl₂ than with the organo mercurial Verdasan.Six of the ten thermophilous species studied showed higher radial growth rates compared with the two fastest growing mesophilic species studied;Trlchoderma viride andZygorhynchus moelleri. While M. pusillus was capable of growth in dry weight at 0.05 ppm of all fine fungicides,Sporotrichum thermophile did not show mycelial growth with Verdasan at 0.05 ppm.Thermomyces lanuginosus showed reduced growth rates with Thiram and no mycelial growth with both HgCl₂ and Verdasan.     

Growth of three fungi on poultry fat or beef tallow

Aspergillus niger, Geotrichum candidum and Mucor miehei, when grown on a medium containing beef tallow or poultry fat for 5 days at 28°C, in Roux bottles, shake-flasks or fermenters, synthesized from 0.4 to 3.2 g lipids/I. The degree of fat utilization varied from 15 to 70%. The type of fat in the medium, the species of fungi and its cultivation method all influenced the fatty acid composition of fats remaining in the medium, as well as the intracellular lipids of the fungi.     

Presence of carotenoids and ergosterol inMucor azygospora and inMucor inaequisporus

The yellow-orange mycelia ofMucor azygospora andM. inaequisporus were analyzed for the presence of carotenoids.Mucor azygospora contained 7 carotenoids with γ-carotene as the principal pigment andMucor inaequisporus the same carotenoids with Β-carotene predominating. The steroid ergosterol was obtained in a crystalline state from the unsaponifiable fraction of both fungi. The author thanks Miss M. Krul for her technical assistance.     

Use of the Zebrafish Larvae as a Model to Study Cigarette Smoke Condensate Toxicity

The smoking of tobacco continues to be the leading cause of premature death worldwide and is linked to the development of a number of serious illnesses including heart disease, respiratory diseases, stroke and cancer. Currently, cell line based toxicity assays are typically used to gain information on the general toxicity of cigarettes and other tobacco products. However, they provide little information regarding the complex disease-related changes that have been linked to smoking. The ethical concerns and high cost associated with mammalian studies have limited their widespread use for in vivo toxicological studies of tobacco. The zebrafish has emerged as a low-cost, high-throughput, in vivo model in the study of toxicology. In this study, smoke condensates from 2 reference cigarettes and 6 Canadian brands of cigarettes with different design features were assessed for acute, developmental, cardiac, and behavioural toxicity (neurotoxicity) in zebrafish larvae. By making use of this multifaceted approach we have developed an in vivo model with which to compare the toxicity profiles of smoke condensates from cigarettes with different design features. This model system may provide insights into the development of smoking related disease and could provide a cost-effective, high-throughput platform for the future evaluation of tobacco products.     

Effect of moisture on lipase catalysed esterification of geraniol of palmarosa oil in non-aqueous system

Summary Optimisation of reaction conditions for the esterification of geraniol of palmarosa oil with n-butyric acid using immobilized lipase from Mucor miehei in non-aqueous system was carried out. Palmarosa oil could be easily esterified upto 95% w/w at 40°C in 24 h. Effect of moisture content was studied using Na₂SO₄ and recycling of the immobilized enzyme.     

Mycoflora of mangrove mud

Summary Thirty-nine species and four varieties of fungi are reported from mangrove mud collected from Kagh Island, Port Canning and Diamond Harbour, West Bengal, India. Of these forms twelve species and two varieties belonged to genusAspergillus and three species belonged, each toMucor, Penicillium andPreussia. Two species both ofFusarium andTrichoderma were also isolated. Two new species,Cladosporium indicum andPaecilomyces indicus and five other interesting fungi are described in detail.     

Role of water activity on the synthesis of geranyl butyrate by a Mucor miehei esterase in a solvent-free system

The initial activity rate for the synthesis of geranyl butyrate by an esterase from Mucor miehei increased with increasing water activity and decreased above 0.5 water activity. The conversion yield after 75 h was about 75% for different, but low, initial water activities and decreased above 0.5 water activity. This behaviour is related to water-enzyme interactions.     

Some keratinophilic fungi from Spain

Summary Three keratinophilic species of Gymnoascaceae obtained in culture and isolated from Spanish soils are described, i.e. Amauroascus kuehnii von Arx, Arachnotheca albicans (Apinis) von Arx and Gymnoascus reticulatus Zukal. All of them are new records from Spain.     

Lipase catalyzed polytransesterification in an organic solvent

Summary Lipase-catalyzed polytransesterification ofbis(2,2,2-trifluoroethyl) dodecanedioate with aliphatic diols (from 1,2-ethanediol to 1,6-hexanediol) was studied with 4 enzymes and a number of solvents. The effects of experimental parameters were investigated with the purpose of obtaining a polyester of as high as possible average molar mass. The highest mass average molar mass (M _w) of 34,750 g mol^-1 (DP = 122) was obtained under vacuum with 1,4-butanediol,Mucor miehei lipase, and diphenyl ether as solvent.     

A Facile Method for Preparation of Polymerizable, Optically Active Ketoprofen Prodrug by Irreversible Lipase-catalysed Resolution

Summary An irreversible resolution of ketoprofen prodrug was developed by lipase-catalysed hydrolysis using corresponding vinyl ester as activated substrate in organic medium. The product obtained, (S)-ketoprofen vinyl ester would be used as a potential prodrug and a significant monomer for polymeric drug. Lipozyme^? immobilized from Mucor miehei showed the highest selectivity and activity after enzyme screening. The effect of solvent, water amount in the reaction medium and reaction temperature on the activity and enantioselectivity of Lipozyme^? was studied. Polymerizable, optically active ketoprofen prodrug could be obtained with excellent enantioselectivity (ee >99%, E ~ 400) in a mixture of dioxane/water (97.5/2.5, v/v) at 25 °C.     

Thermophilic and thermotolerant fungi in poultry droppings in Nigeria.

Ten species of fungi were obtained from poultry droppings in Nigeria. Six of these are true thermophiles while the other four are thermotolerant. Aspergillus fumigatus Fresenius, Mucor pusillus Lindt and Thermoascus aurantiacus Stolk are known human pathogens. Except for M. pusillus, all the thermotolerant species had a higher occurrence at 45 degrees C while the thermophilic varieties were readily obtained at 50 degrees C.     

Lipase catalysed synthesis of sugar ester in organic solvents

Summary The synthesis of sugar esters catalysed by lipase in organic solvents was studied. Immobilized Candida and Mucor miehei lipase catalysed the synthesis of fructose and glucose esters of stearic acid in tertiary butyl alcohol with yields of 10 to 24 %. In the presence of phenyl or butyl boronic acid synthesis of glucose ester was achieved in hexane, heptane, benzene and toluene. The only positive reaction on disaccharides was found with palatinose.     

Distribution of fungi on two mite species and their habitats in Egypt

Fungi associated with two mite species,Acotyledon krameri andTyrophagus putrescentiœ, and their habitats were studied using 1% glucose-Czapek's and potato-dextrose agar media at 28±2°C. A total of 54 species and one variety belonging to 25 genera were recovered from different habitats of mite species; 36 species and one variety belonging to 18 genera were associated with mite bodies. Nearly most fungal species isolated from mite bodies were also encountered in their habitats. The most common species wereAspergillus flavus, A. fumigatus, A. niger, Mucor racemosus, Nectria hœmatococca. A. terreus, Scopulariopsis brevicaulis andTrichurus spiralis were isolated only from mite bodies whereasFusarium oxysporum, Penicillium chrysogenum, P. corylophilum, P. funiculosum andRhizopus stolonifer were recovered from the mite habitats.A. krameri individuals survived well onCunninghamella elegans, F. oxysporum andM. racemosus cultured on both type of media, whereasCylindrocarpon destructans was best forT. putrescentiœ survival.