nystatin-a1 and n-hexadecane

In this study, the impact of bacterial and fungal processes on (14)C-hexadecane mineralisation was investigated in weathered hydrocarbon contaminated soil. The extent of (14)C-hexadecane mineralisation varied depending on the bioremediation strategy employed. Under enhanced natural attenuation conditions, (14)C-hexadecane mineralisation after 98 days was 8.5 ± 3.7% compared to <1.2% without nitrogen and phosphorus additions. (14)C-hexadecane mineralisation was further enhanced through Tween 80 amendments (28.9 ± 2.4%) which also promoted the growth of a Phanerochaete chyrsosporium fungal mat. Although fungal growth in weathered hydrocarbon contaminated soil could be promoted through supplementing additional carbon sources (Tween 80, sawdust, compost, pea straw), fungal (14)C-hexadecane mineralisation was negligible when sodium azide was added to soil microcosms to inhibit bacterial activity. In contrast, when fungal activity was inhibited through nystatin additions, (14)C-hexadecane mineralisation ranged from 6.5 ± 0.2 to 35.8 ± 3.8% after 98 days depending on the supplied amendment. Bacteria inhibition with sodium azide resulted in a reduction in bacterial diversity (33-37%) compared to microcosms supplemented with nystatin or microcosms without inhibitory supplements. However, alkB bacterial groups were undetected in sodium azide supplemented microcosms, highlighting the important role of this bacterial group in (14)C-hexadecane mineralisation.

Topics: Alkanes; Analysis of Variance; Bacteria; Biodegradation, Environmental; Carbon Radioisotopes; Cluster Analysis; Nitrogen; Nystatin; Petroleum; Phanerochaete; Phosphorus; Polymerase Chain Reaction; Polysorbates; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Sodium Azide; Soil Pollutants

Techniques are described which allow mutated populations of Candida cloacae to be enriched efficiently (up to 167-fold in one round of enrichment) for mutants deficient in the alkane degradation pathway (Alk-). Such mutants, as well as being of scientific importance in studies of the degradation pathway, are also of commercial interest because several of the degradative intermediates are of value to the chemical industry. The Alk- mutants were readily isolated by their inability to grow on agar plates supplied with hexadecane as sole carbon source. A total of 288 Alk- mutants were isolated from, effectively, 4 x 10(6) mutagen-treated cells. They were further characterized by replica-plating using palmitic acid (PA) or acetate (Ac) as sole carbon source. Preliminary screening studies showed that of the 84 Alk- PA- Ac+ mutants, most could accumulate dicarboxylic acids from hexadecane and palmitic acid and at least one mutant also produced 3-hydroxyhexadecanedioic acid. Of the 80 mutants characterized as Alk- PA+, 16 produced small amounts of hexadecanol.

Topics: Alkanes; Amphotericin B; Antifungal Agents; Candida; Mutation; Nitrogen; Nystatin; Palmitic Acids