Pp.S. Handley

Fungi are the predominant micro-organisms responsible for degradation of soil-buried polyester polyurethane over a range of soil water holding capacities

Aims: To investigate the relationship between soil water holding capacity (WHC) and biodegradation of polyester polyurethane (PU) and to quantify and identify the predominant degrading micro‐organisms in the biofilms on plastic buried in soil.

Comparative susceptibility of resident and transient hand bacteria to para-chloro-meta-xylenol and triclosan

Aims: To determine the susceptibility of planktonic and biofilm‐grown strains of resident and transient skin bacteria to the liquid hand soap biocides para‐chloro‐meta‐xylenol (PCMX) and triclosan. 
Methods and Results: Freshly isolated hand bacteria were identified by partial 16S rRNA gene sequencing. Two resident and three transient strains, as well as four exogenous potential transient strains, were selected for biocide susceptibility testing. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of planktonic cells were determined. Resident and transient strains showed a range of susceptibilities to both biocides (PCMX, MIC 12˙5–200 mg l−1, MBC 100–400 mg l−1; triclosan, MIC 0˙6– > 40 mg l−1, MBC 1˙3– > 40 mg l−1). Strains were attached to polystyrene plates for 65 h in 96‐well microtitre plates and challenged with biocide to determine the biofilm inhibitory concentration and biofilm eradicating concentration. For all strains tested, biofilms were two‐ to eightfold less susceptible than planktonic cells to PCMX. 
Conclusions: Very few transients were detected on the hand. Transients were not more sensitive than residents to the biocides and susceptibility to PCMX and triclosan was strain dependent. Biofilm‐grown strains were less susceptible to PCMX than planktonic cells. 
Significance and Impact of the Study: The study provides increased knowledge about the susceptibility of skin bacteria to biocides present in typical liquid antibacterial hand soaps and suggests that the concentration of biocide employed in such products is in excess of that required to kill the low numbers of transient bacteria typically found on skin.

Influence of growth environment on coaggregation between freshwater biofilm bacteria

Aim:  To characterize the expression of coaggregation between Blastomonas natatoria 2.1 and Micrococcus luteus 2·13 following growth in liquid culture, on agar and in an artificial biofilm matrix composed of poloxamer hydrogel.

Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil

ABSTRACT This work investigated biostimulation and bioaugmentation as strategies for removing polyurethane (PU) waste in soil. Soil microcosms were biostimulated with the PU dispersion agent “Impranil” and/or yeast extract or were bioaugmented with PU-degrading fungi, and the degradation of subsequently buried PU was determined. Fungal communities in the soil and colonizing buried PU were enumerated on solid media and were analyzed using denaturing gradient gel electrophoresis (DGGE). Biostimulation with yeast extract alone or in conjunction with Impranil increased PU degradation 62% compared to the degradation in untreated control soil and was associated with a 45% increase in putative PU degraders colonizing PU. Specific fungi were enriched in soil following biostimulation; however, few of these fungi colonized the surface of buried PU. Fungi used for soil bioaugmentation were cultivated on the surface of sterile wheat to form a mycelium-rich inoculum. Wheat, when added alone to soil, increased PU degradation by 28%, suggesting that wheat biomass had a biostimulating effect. Addition of wheat colonized with Nectria haematococca, Penicillium viridicatum, Penicillium ochrochloron, or an unidentified Mucormycotina sp. increased PU degradation a further 30 to 70%, suggesting that biostimulation and bioaugmentation were operating in concert to enhance PU degradation. Interestingly, few of the inoculated fungi could be detected by DGGE in the soil or on the surface of the PU 4 weeks after inoculation. Bioaugmentation did, however, increase the numbers of indigenous PU-degrading fungi and caused an inoculum-dependent change in the composition of the native fungal populations, which may explain the increased degradation observed. These results demonstrate that both biostimulation and bioaugmentation may be viable tools for the remediation of environments contaminated with polyurethane waste.

Influence of starvation, surface attachment and biofilm growth on the biocide susceptibility of the biodeteriogenic yeast Aureobasidium pullulans

Aims:  To investigate the effect of starvation, surface attachment and growth in a biofilm on the susceptibility of Aureobasidium pullulans to the biocides 2‐n‐octyl‐4‐isothiazolin‐3‐one (OIT) and sodium hypochlorite (NaOCl).

In situ quantification of biocide efficacy using GFP transformed Aureobasidium pullulans

Aims:  To develop a real‐time in situ method to quantify loss of viability of Aureobasidium pullulans PRAFS8 cells attached to plasticized polyvinyl chloride (pPVC) with incorporated biocides, and to use the method to compare biocide efficacy in situ.