Safety evaluation of phosphodiesterase derived from Leptographium procerum.

5'-Phosphodiesterase is produced by fermentation of the fungus Leptographium procerum and is used to hydrolyse yeast RNA to produce flavour enhancers. To establish the safety in use of this enzyme preparation a number of studies have been performed: analysis for the potential of the production strain to produce toxic secondary metabolites, 28-days oral toxicity study of the preparation in the rat, bacterial mutation assay and in vitro mammalian chromosome aberration test in human lymphocytes. The production strain did not produce any secondary metabolites that may be of significance in food. Administration of dosage levels of 1250, 2500 and 5000 mg/kg body weight/day to rats for 28 day did not result in any toxicological significant changes. The enzyme preparation showed no mutagenic activity in the bacterial mutation assay and no clastogenic potency in an in vitro test. These results together with existing knowledge of the production organism and the chemical and microbiological characterisation of the enzyme preparation lead to the conclusion that the enzyme preparation containing 5'-phosphodiesterase activity from Leptographium procerum can safely be used for the production of flavour enhancers from bakers yeast at the anticipated intake levels for these uses.

On the safety of Aspergillus niger--a review.

Aspergillus niger is one of the most important microorganisms used in biotechnology. It has been in use already for many decades to produce extracellular (food) enzymes and citric acid. In fact, citric acid and many A. niger enzymes are considered GRAS by the United States Food and Drug Administration. In addition, A. niger is used for biotransformations and waste treatment. In the last two decades, A. niger has been developed as an important transformation host to over-express food enzymes. Being pre-dated by older names, the name A. niger has been conserved for economical and information retrieval reasons and there is a taxonomical consensus based on molecular data that the only other common species closely related to A. niger in the Aspergillus series Nigri is A. tubingensis. A. niger, like other filamentous fungi, should be treated carefully to avoid the formation of spore dust. However, compared with other filamentous fungi, it does not stand out as a particular problem concerning allergy or mycopathology. A few medical cases, e.g. lung infections, have been reported, but always in severely immunocompromised patients. In tropical areas, ear infections (otomycosis) do occur due to A. niger invasion of the outer ear canal but this may be caused by mechanical damage of the skin barrier. A. niger strains produce a series of secondary metabolites, but it is only ochratoxin A that can be regarded as a mycotoxin in the strict sense of the word. Only 3-10% of the strains examined for ochratoxin A production have tested positive under favourable conditions. New and unknown isolates should be checked for ochratoxin A production before they are developed as production organisms. It is concluded, with these restrictions, that A. niger is a safe production organism.

Containment in industrial biotechnology within wastewater treatment plants.

Both physical and biological containment are considered to be essential parts in the risk analysis of industrial Good Industrial Large-Scale Practice (GILSP) processes using genetically modified organisms (GMOs). Biological containment of industrial microorganisms has become a more important issue since the introduction of recombinant DNA techniques. In the event of an accidental discharge in the production plant, a large amount of organisms could be released into the wastewater treatment (WWT) system. This WWT system should therefore be considered as a part of the containment. This study demonstrates both a hydrodynamic and a microbiological model for the containment aspects of industrial WWT plants. The models are verified by measurements using industrial hosts of GILSP GMOs at full scale. Both models describe the full-scale equipment accurately. The results are supplemented with microcosm studies on survival of GMOs in defined niches. It is shown that WWT plants can be considered as useful additional parts of the containment of microorganisms, in case of an accidental discharge. The effect of drainage of an enormous amount of microorganisms (several tons) through the WWT plant into the environment is shown to be comparable to the direct drainage of a small-scale fermenter. Microcosm experiments correlate well with the survival rates in the WWT and therefore can be of use to predict the behaviour of GMOs in this environment.