Fungi biocide resistance

The data in Table 13.10 show a high level of performance of the biocide against all the test fungi. A. niger was more resistant in the Disk Test, but equally well suppressed in the NSA Test. 

Phenyl diisocyanate (VIII) was used as a grafting molecule following the same strategy discussed above in the case of the double anhydride in [14—17]. As expected, the FTIR spectrum of the modified wood surface, after extraction of the unreacted VIH, displayed a strong peak at 2 250cm, characteristic of the presence of isocyanate functions (see Fig. 20.5). These modified wood samples were treated with the biocides IV and V, which provided an excellent resistance to fungi [18]. 

OBPA is a biocide, that means it is not only toxic to microbes but also to fish and other living species. Its antimicrobial effectiveness is similar to that of organo-mercurials covering a broad spectrum of bacteria, yeasts and mould producing fungi (minimum inhibition concentrations approx. 10 mg OBPA/litre). Among the fungal species Scopulariopsis brevicaule is relatively resistant to OBPA under use conditions. 

There is no evidence associating the presence or acquisition of plasmids with resistance to biocides in fungi, although acquired resistance (non-plas-mid) of yeasts to organic acids has been demonstrated [254]. 

ASTM G 22, Resistance of Plastics to Bacteria The test protocol is similar to G 21 specimens are inoculated (usually) with Pseudomonas aeruginosa, an opportunistic soil bacterium that is a hazard to immune-compromised persons. The zone of inhibition is sometimes determined. This should not be combined with fungus resistance testing, as Pseudomonas can metabolize a variety of fungi (instead of the biocide-containing nutrient). 

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