Essential oils are frequently used for flavour and fragrance in the perfume, pharmaceutical, cosmetic and food industries. The antimicrobial activities of the essential oils of Artemisia afra, Pteronia incana and Rosmarinus officinalis were tested against 41 microbial strains. The test organisms were selected on the basis of their significance as food spoilage and/or poisoning, common human and plant pathogens. The agar diffusion assay was performed using nutrient agar and antibiotic medium. All the oils tested displayed some antimicrobial activities. However, the efficiency differed and depended both on the type and concentration of the oil, as well as the test microbial strain. Artemisia afra and R. officinalis showed similar and higher antimicrobial activity than P. incana. Due to their broad antimicrobial activities, the essential oils of the above plants growing in Eastern Cape may have preservative potential for the food and cosmetic industries.

The use of essential oils in the production of cosmetics and related products may have several advantages, such as enhancing the dermato-cosmetic properties and preservation, as well as the marketing image of the final product. The use of botanical materials such as essential oils in cosmetic formulations at relatively high concentrations is likely to provide skin benefit. The potential of essential oils indigenous to the tropical and subtropical part of Africa has not been sufficiently exploited in this regard. Using a challenge test, this study demonstrates the potential application of two South African indigenous plant essential oils, viz. Artemisia afra and Pteronia incana oils, and oils of two Mediterranean aromatic plants grown in South Africa, viz. Lavandula officinalis, and Rosmarinus officinalis, to be used as natural cosmetic preservatives in an aqueous cream formulation. Except for Pseudomonas aeruginosa strains, the oils displayed remarkable antimicrobial activities against all common test organisms (including bacteria and fungi) and environmental isolates used. All the test microorganisms used in this study were generally more susceptible to the oils during the challenge test in aqueous cream compared to the antimicrobial test performed on agar. The results indicate, therefore, that the oils can be recommended as candidate natural cosmetic preservatives. Artemisia afra oil was the most efficient in reducing the load of artificial contaminations in the aqueous cream formulation within 2-7 days. Since relatively high concentrations of the oils were used, the oils could at the same time serve as natural fragrances in aqueous cream, in addition to assuring protection against microbial contamination.

The Umtata River was characterised by using standard physico-chemical and microbiological methods to assess the present water quality in the river. The results indicated high turbidity, gross microbiological and cadmium pollution. Turbidity values ranged from 0.28 NTU to 1 899 NTU highlighting the known problem of donga erosion in the catchment. Faecal coliform counts varied between 0 and 21 000 counts/100 ml while the total coliform counts ranged from 0 to 69 000 counts for all the sites sampled. The levels of cadmium varied between 0.01 mg/l and 1.0 mg/l. Nutrient levels were also high. Nitrate values ranged from 0.01mg/l to 28.0 mg/l as N while phosphate values varied between 0.02 mg/l and 5.0 mg/l as P. The high coliform counts and the nutrient values exceeding acceptable limits are indicative of pollution from domestic wastes from several informal settlements located along the riverbank. Water uses in the area were determined and were found to be mainly domestic and recreational. The gross pollution of the river exposes the local people who depend on it for their primary water source to serious health risk. Another use included livestock watering.

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This study (i) investigated changes that take place during the composting of tobacco wastes with other organic materials, (ii) characterized the resulting composts, and (iii) evaluated their agronomic effectiveness. Four composts were made, all of which contained tobacco waste and sawdust/wood shavings but differed in the third ingredient, which was either cow dung, pig dung, poultry manure or cabbage waste. Changes in pH and electrical conductivity (EC) during composting were consistent with those generally observed, in spite of the presence of toxic tobacco wastes. Changes in temperature regime and the results of a bioassay (germination test) suggested that compost maturity was achieved after 45-59 days in all four composts. Mixing of tobacco waste with other organic wastes reduced the nicotine content of tobacco wastes from 12180 mg kg-1 to 4872 mg kg-1 by dilution while composting reduced it further to < 160 mg kg-1 in the final composts. Tobacco waste had a depressing effect on microbial activity in soil but the composts stimulated it, possibly as a result of their lower EC and reduced nicotine and related alkaloid levels.All final composts had C:N ratios < 17 and so were considered conducive to N mineralization and thus suitable for horticultural use. However, they had high electrical conductivity (6.0 to 9.3 mS cm-1 ) and may not be ideal for salt-sensitive crops or as sole components in horticultural growing media without modification. Application of the composts to soil (to supply 80 mg N kg-1 ) improved the growth of lettuce relative to the control and uncomposted tobacco waste but full growth potential was not attained due to inadequate nitrogen supply. A subsequent experiment with spinach designed to address the N limitation revealed that satisfactory yields could be obtained by the application of 20 t ha-1 cow dung compost or 10 t ha-1 compost in combination with NPK fertilizer supplying 50 kg N ha-1 • *Corresponding author-pmnkeni @ufh.ac.za 101 Downloaded by [University of South Carolina ] at 01:56