Christopher W. Lewis

Increased cytotoxicity of food-borne mycotoxins toward human cell lines in vitro via enhanced cytochrome p450 expression using the MTT bioassay

Eight food-borne mycotoxins epidemiologically implicated in human disease were tested for their cytotoxic effects on human cells previously immortalised and transfected to introduce human cytochrome p450(CYP 450) genes. Such cells retain many characteristics of normal cell growth and differentiation while simultaneously having the potential of either increasing or decreasing the metabolic activity (cytotoxicity) of the challenging mycotoxins. The MTT assay provided an indication of cytotoxicity. Of the nine CYP 450s introduced CYP1A2 was most effective,rendering the cells 540 times more sensitive than the control cells to aflatoxin B1, 28 times more sensitive to aflatoxin G1 and 8-fold more sensitive to ochratoxin A. CYP3A4 resulted in the cells being 211 times more toxic to aflatoxin B1 and 8-fold more toxic to aflatoxin G1 while CYP 2A6, CYP 3A5 and CYP 2E1 also produced observable effects. No increase in metabolic activity was found using cyclopiazonic acid, deoxynivalenol,fumonisin B1, patulin or T-2 toxin. CD5Os were calculated for the mycotoxins against the non-CYP-introduced control cells. There was almost a five order of magnitude difference between the most toxic,T-2 toxin (CD50 0.0057 μg/ml) and the least toxic, fumonisin 1(CD50 476.2 μg/ml). In vitro biological assays thus provide an excellent system for quantifying the often low CD50s expressed bymycotoxins in foods.

Fuels from biomass—energy outlay versus energy returns: A critical appraisal

The concept of fuel production by the microbial conversion of biomass is discussed with particular emphasis upon the energy implications involved. Both the energy requirements and energy returns for a number of selected systems are assessed in the light of current technology, while areas for future improvements are also mentioned.

The Presence of Mycotoxin-Associated Fungal Spores Isolated from the Indoor Air of the Damp Domestic Environment and Cytotoxic to Human Cell Lines

One hundred and fifty-two fungal isolates from the air spores of 503 damp, mouldy dwellings in Glasgow and Edinburgh, Scotland, were screened for cytotoxicity against the human embryonic diploid fibroblast lung cell line, MRC-5 (ATTC No. CCL171). At least 37% of the isolates, principally of the genus Penicillium, showed toxicity to the cells when subjected to the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay follow ing a water extraction procedure. When spores of 23 of the isolates were sub jected to extraction with the organic solvent dimethyl sulphoxide, an addition al level of cytotoxicity was observed separate from the water extraction meth ods. Many mycotoxins are known to be sparingly soluble in water. When some of these isolate extracts were exposed to human Chang liver cells (ATCC No. CCL13) and to human normal sternal bone marrow cells, (Detroit 98, ATCC No. CCL18), some additional cytotoxicity was observed. A comparison was also made, in some cases, between results obtained in the MTT and neutral red assays. Organisms exhibiting the greatest cytotoxicity included Penicil lium viridicatum, P. expansum, P. chrysogenum, P. commune and Aspergillus fumigatus.

A net energy analysis of fuels from biomass: the case of Nigeria

Abstract Nigeria is a major world oil producer; yet fossil fuel consumption was only 6·6 GJ capita−1 in 1983, below that of several poorer African states. With the population growing at 3.3% and deforestation at 2.2% annually, the countrys fossil and traditional biomass resources are under pressure. Net energy analysis has been used here as an indicator of which biofuel options to pursue within a diversified national energy strategy. Afforestation of 100 000 hectares annually could provide 30 PJ year−1 of fuelwood. The anaerobic digestion of 25% of the countrys cattle manure would yield 15 PJ of biogas each year plus 50 × 103 t of fertiliser nitrogen. Both cassava and maize use as feedstocks for bioethanol production lead to low net energies, while those sorghum and sugarcane are much higher at 118·5 GJ ha−1 year−1 and 95·2 GJ ha−1 year−1, respectively. Sorghum however is a staple food. An area of 97 × 103 hectares of sugarcane could produce sufficient ethanol for inclusion in gasohol at the 10% level throughout Nigerias fleet of petrol-driven vehicles.

Health-Related Aspects of the Genus Aspergillus

While the genus Aspergillus is now recognized to contain approximately 200 species and varieties (Samson and van Reenen-Hoekstra, 1988), fewer than half a dozen are considered to be important implicating factors in human disease, notably A. fumigatus, A. flavus, A. niger, A. nidulans, and A. terreus (Evans and Gentles, 1985). Aspergillus wentii, A. amstelodami, A. repens, A. ruber, A. niveus, A. candidus, A. conicus, A. carneus, A. ustus, A. oryzae, A. glaucus, A. clavatus, A. restrictus, A. parasiticus, A. sydowii, A. tamarii, A. ochraceus, A. flavipipes, A. fischeri, and A. versicolor (Rogers and Kennedy, 1991) are among the second, less important group of healththreatening species, largely through their ability either to produce toxic secondary metabolites or to cause infections in humans and other animals or to do both.

The incidence of moulds within 525 dwellings in the United Kingdom

Airborne viable mould spore counts were determined for living rooms, kitchens and bedrooms within 503 council houses in Edinburgh and Glasgow (UK); at least one child lived in each house. Approximately one‐half of the 1709 rooms sampled contained 300 cfu m‐3, indicating a positive relationship between surface growth and air spore levels. The most common genera isolated from internal surfaces (including those from a further 22 London houses) were identified.

Biomass through the ages

Abstract Biomass energy, in the form of wood, had fuelled the worlds economy for thousands of years before the advent of more easily winnable coal and subsequently oil, gas and uranium. The Industrial Revolution in England 200 years ago saw the West begin to embark upon the fossil fuel era-an era which we now appreciate as being a short-lived one. Bioenergy is now once more a recognised fuel supply option in the developed world, just as it has continued to be in the Third World. Highlights of the history of biomass energy use are documented in this paper, which attempts to show that innovations made in the past demonstrate that the concept of biological energy production is by no means revolutionary, and that it has the potential to return again as a major supply to the West as well as to the developing countries where it remains so indispensable even today.

Biomass assessment in third world villages via a systems methodology

Abstract Using a systems analysis methodology, the potential of indigenously produced biomass to enhance the development of a Third World rural community can be gauged through time. An integrated system of physical and biosolar technologies, allied to improvements in traditional agriculture, is demonstrated to increase output and decrease the need for expensive energy intensive imports such as diesel for irrigation and chemical fertilisers for maximising crop productivity. Under the conditions simulated for an existing Indian village, food consumption can increase by around 200%, indigenous energy production by 85% and overall solar energy capture by just over 150% - all within 12 years. Even with a population growth rate of 2% per annum, the scenario proposed is robust enough to maintain improved living standards well into the next century. Should such a strategy for decentralised development be extensively adopted then it could benefit a significant proportion of the people currently living in the rural areas of the Third World.

Efficiency improvements in bioenergy conversion systems

Abstract A discussion of the main bioenergy conversion systems is presented, including their respective efficiencies and how these are being improved. The concept of net energy analysis is also introduced as a guideline for determining system efficiencies and process selection. Combustion remains the most efficient conversion method for dry organic matter, with anaerobic digestion and ethanolic fermentations preferred for biomass containing a high percentage of water. The efficiencies of gasification, pyrolysis and the longer term proposition of biophotolysis are also covered. While most of the data presented accrues from industrialized, intensive systems it is envisaged that bioenergy will make its greatest impact within the nations of the Third World.

Biofeedstocks and land use in Western Europe.

Abstract This article assesses the impact of biotechnology on the manufacture of biofuels and commodity and speciality chemicals over the next 10–15 years within Western Europe. Demand projections are made for the products under review, the biomass feedstock requirements and the resulting effects on land use policy. It is concluded that in order for biotechnology to make a great impact on land use policy in Western Europe, a large ethanol-from-biomass programme must be set in motion. Land is available for such an initiative, but the main objection is the economic one and the need for subsidies.