Sterol and fatty acid composition were combined for comparison of five industrially important Aspergillus species. Quantitative amounts of individual fatty acids, especially unsaturated ones, and the composition of sterols showed the differences among fungi examined. Besides ergosterol, six other sterols were present in detectable amounts in fungal mycelia. The most outstanding were the differences in the amounts of linolenic acid, ergosterol, and lanosterol, as well as in a sterol with M+376 identified as ergosterol peroxide.

Aspergillus niger strain MZKI A116 was used to produce lipolytic enzymes in submerged culture. Lipase production was induced by addition of olive oil to a complex medium with an initial pH of 5.0. Maximal activity was reached after 70 h in a 15 1 bioreactor at 30 °C with aeration of 0.5 vvm and agitation 400 rpm. Optimal temperature and pH conditions for the action of the lipases tested on tributyrin were 45 °C and pH 7.0. Triacetin and tributyrin were shown to be the best substrates. The presence of iron and silver ions at low concentrations did not alter the activities. Two enzymes possessing lipase activity were isolated by acetone precipitation followed by ion-exchange chromatography. The molecular weights were 43 kDa and 65 kDa with isoelectric points of pH 4.1 and 4.2, respectively. The higher molecular weight lipase showed preference toward 1- and 3-positions of the triglyceride molecule and was stereoselective for the sn-1 position with an enantiomeric excess of 20%. It displayed strong activity toward naphthyl, indolyl, umbelliferyl and resorufin esters and was active on esters of hydroxynaphthoic acid anilide, while it showed no activity toward esters of hydroxypyrene trisulfonic acid.

A new species of Mucor, M. troglophilus Zalar, is described from a cave in Slovenia, in association with the cave cricket Troglophilus neglectus. The species is closely related to M. bacilliformis, but differs by the shape and size of the sporangiospores, of the columellae and of the arthrospores, and by the natural ability of producing a persistent yeast phase in aerobic as well as anaerobic conditions.

During the study of mevinolin biosynthesis by Aspergillus terreus ATCC 20542, 10 different medium components were selected for medium optimization. A new optimization method based on genetic algorithms and inductive learning was used for experimental design. For better efficiency the method was supported by a model, constructed with machine learning method, to predict the productivity. In four generations of fermentation experiments the productivity increased nearly three times.

Screening of different yeast species showed that they are able to synthesize hydroxymethylglutaryl-CoA (HMGCoA) reductase inhibitors. Crude methanol extracts and the purified inhibitors from Pichia labacensis and Candida cariosilignicola were tested for their biological activity on the solubilized microsomal HMGCoA reductase from Chinese hamster ovary cells. Identification of the inhibitors was studied by thin layer chromatography, high pressure liquid chromatography and mass spectroscopy.

High-performance liquid chromatographic analysis of mevinolin in fermentation broth was initially performed after addition of acid and extraction with methanol using a mobile phase at pH 3.0. Under such conditions mevinolin was present in three different forms: as a lactone, as the corresponding ß-hydroxy acid (mevinolinic acid) and as its methyl ester. To achieve accurate and reproducible results the method was modified such that only one form was present: mevinolinic acid. The fermentation broth samples were adjusted to pH 7.7 before the extraction with methanol, and the pH of the mobile phase was adjusted to 7.7 as well. For the separation a 250 × 4 mm I.D. column, termostated at 40°C, packed with Spherisorb ODS 2 of 5 μm particle size was used. Under these conditions mevinolin was detected at 237 nm as a single peak of a ß-hydroxy acid, which has the lowest retention time of all three forms.

Two baker's and two brewer's yeast strains of Saccharomyces cerevisiae were compared. Regarding their cell composition there was almost no difference in proteins and nucleic acids. Differences were observed in total lipid amounts as well as in lipid composition. Baker's yeasts contained only about one half as much lipids as the brewer's yeasts. Among phospholipids phosphatidylethanolamine prevailed in all strains tested. The phosphatidylcholine content was almost ten times higher in brewer's yeasts whereas the amounts of phosphatidylserine and phosphatidylinositol were two to three times higher in baker's yeast strains. The ratio of saturated to unsaturated fatty acids was always lower with brewer's yeasts. The differences in fatty acid composition were less pronounced than the differences in phospholipid composition.

Gunde-Cimerman, N., and Cimerman, A. 1995. Pleurotus fruiting bodies contain the inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase-lovastatin. Experimental Mycology 19, 1-6. In the fruiting bodies of the fungus Pleurotus ostreatus, also called the oyster mushroom, we found a competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase—lovastatin. The appearance of the inhibitor during the development of fruiting bodies was followed and lovastatin determined in the vegetative mycelium, in the primordia, as well as in different parts of sporocarps of different sizes. Less lovastatin was found in stipes as compared to pili or in mature stages in the lamellae and basidiospores.

Lipase biosynthesis occured in medium without lipids, but for improved production an inducer was needed. The source and concentration of an inducer had no signifficant effect. Starch as an additional carbon source stimulated lipase biosynthesis when used in small amounts. Addition of NH4NO3 as a nitrogen source, KH2PO4 as a phosphate source as well as Mg ions to the medium with inital pH 5.0 gave the best yield.

Different methods are compared for the preservation of a Rhizomucor miehei strain used for the production of rennet, which is used in the dairy industry. The best method was found to be preservation under mineral oil, After 2 years of storage, R. miehei kept its original milk clotting activity, had a lowered non-specific proteolytic activity and therefore a higher specific activity.

Pectolytic enzymes were synthesized during the cultivation of Aspergillus niger in a medium with decationized commercial sugar at concentration of 140 g l−1. Cultivation experiments were performed in a 10-l stirred-tank bioreactor. During the period of pronounced dissolved oxygen consumption, aeration and agitation had to be increased stepwise up to 1 vvm and 600 rev min−1 after 60 h. The pH value of the broth decreased during this period to 2.2 and remained low. Reducing sugars first increased due to the hydrolysis of sucrose; later they steadily decreased and were nearly entirely consumed. Ammonium nitrogen was depleted earlier. After about 40 h an increase in biomass and extracellular soluble protein could be detected. Maximal values of pectolytic activities were attained within 140 to 180 h and amounted to 375 U ml−1 for apple juice depectinizing activity, 88% for pectin viscosity reduction activity, 3 U ml−1 for polygalacturonase (EC 3.2.1.15), 13 U ml−1 for pectinesterase (EC 3.1.1.11), and 0.5 (extinction) for pectin lyase (EC 4.2.2.10). Maximal biomass concentration was 13 g l−1, which was low considering the high concentration of sugar in the medium. On the other hand, a high concentration of extracellular soluble dry matter was present at the end of the process even though the yields of soluble protein amounted only to 0.6 g l−1. It was shown that the remaining extracellular soluble dry matter was due to citric acid, which had been produced in amounts of up to 60 g l−1 thus constituting a useful by-product.

Fungi of the genus Pleurotus were shown to produce the 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor mevinolin. Crude methanol extracts and the purified inhibitor from three different species, P. sapidus, P. saca and P. ostreatus, were tested using the solubilized microsomal HMGCoA reductase from Chinese hamster ovary cells. The identity of the inhibitor was also confirmed by thin layer chromatography, high pressure liquid chromatography and mass spectroscopy.

Simple sugars were used as C-sources to test whether the chosen Aspergillus niger strain was able to synthesize pectolytic enzymes in a substrate without pectic substances. The most promising results were obtained on commercial sugar (sucrose) which was previously deionized by using a cation exchange resin. Some pectolytic activities such as pectinesterase (PE) and pectin lyase (PL) were similar to those obtained when using a pectin containing substrate. Apple juice depectinizing (AJDA) activity and polygalacturonase (PG) were considerably higher in the sucrose medium. By increasing the sugar concentration from 1.5% to around 15%, the activities increased as follows: AJDA from 15 up to 750 U/ml, PG from 1.8 up to 20 U/ml and PL from 0.14 to 0.65. PE activity was not affected by the sugar concentration. With 14% sugar and other substrate constituents proportionally increased, no benefit was observed with respect to pectolytic activities.

Aspergillus niger was grown in two substrates, one producing a high excretion of citric acid into the media and another which hinders it. In both cases big differences in individual mycelial constituents were observed during the cultivation period. In citric acid accumulating conditions the synthesis of lipids and nucleic acids in fungal mycelia stopped after an initial increase, and did not change till the end of the process; whereas in nonproductive pellets both lipids and nucleic acids increased during the whole period of cultivation. Concomitantly big differences were also observed with intra- and extra-cellular proteins and amino acids, extra-cellular keto acids, and intracellular tricarboxylic acid cycle acids.

A survey of data on composition, properties, and possibilities of disposal or treatment of fruit distillery wastes is presented. Fruit distillery wastes contain high amounts of organic matter and have a pH of 3.3–4.5. The slimy nature of some constituents impairs simple filtration or sedimentation. Comparing different ways of treating distillery wastes, a bioconversion process using filamentous fungi seems to be promising. A production scheme is given. In addition to the elimination of the troublesome wastes, some useful products can be recovered. Filter cake can be used as a protein-enriched feed, and enzymes can be recovered from the filtrate.

A large number of submerged citric acid fermentations in a beet molasses substrate was studied. The development of Aspergillus niger from conidia to pellets was followed. Rheological characteristics of the fermentation broth including the pellets were determined. The results obtained confirm the fact that the non-Newtonian pseudoplastic behaviour of the fermentation broth was due to the presence of mycelial pellets. The most significant changes in rheological properties occurred during the period of maximal citric acid production and increase in biomass.

A comparative study of the lipid composition of Aspergillus niger mycelia was done. The amount of total lipids in mycelia grown in the presence of manganese was up to two times higher than in conditions favoring citric acid accumulation (Cu2+ present). Among individual lipid classes, the amounts of phospholipids and neutral lipids were lower under managese deficiency. Regarding phospholipid composition, phosphatidylethanolamine and diphosphatidylglycerol prevailed under citric acid accumulating conditions, whereas under restricted citric acid biosynthesis, phosphatidylcholine was present in larger amounts. Regarding the fatty acid composition, unsaturated acids predominated in all mycelial samples tested. The ratio of saturated to unsaturated acids was always lower in accumulating conditions. There was more linolenic acid and less palmitic and stearic acid when citrate was accumulated.

Aspergillus niger (ATCC 6275, A-98) was mutated by gamma rays and N-methyl-N′-nitro-N-nitrosoguanidine. Selected mutants were tested in fermentation on apple distillery waste substrates to get improved hydrolytic activities and technological properties, e.g. improved filtration, reduced values for chemical oxygen demand and higher raw protein content in the dry filter cake. A scheme of the combined mutagenic treatment is given. A mutant selected after the fourth series of mutagenic treatment was compared with the parent strain and found to have four times higher endo-1,4-β-d-glucanase (1,4(1,3;1,4)-β-d-glucan 4-glucanohydrolase, EC 3.2.1.4) and exo-1,4-β-d-glucanase (1,4-β-d-glucan cellobiohydrolase, EC 3.2.1.91) activities, ten times higher aryl-β-d-glucosidase activity and essentially higher pectolytic and amylolytic activities than the parent strain.