Molekularbiologische Charakterisierung von Pilzen in Paddy Soils

Pilze haben in Reisböden (Paddy Soils) eine große Bedeutung für den Abbau von Reis-stroh. Ihre Aktivität und Diversität wird dabei im Wesentlichen durch die sich im Laufe einer Reisanbauphase ändernden Feuchte-zustände beeinflusst. Da durch Verfahren der Kultivierung nur ein geringer Teil der im Boden vorhandenen Pilze erfasst werden kann, wurden moleku-larbiologische Methoden eingesetzt, um die Pilzgemeinschaften in drei unterschiedlichen Paddy Soils Süd-Ost Chinas zu untersuchen. Mit diesem Ansatz konnten Populationsshifts aufgezeigt werden, die sowohl durch die Austrocknung von Paddy Soils als auch durch unterschiedliche Reisstrohapplikatio-nen hervorgerufen wurden

Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801

<div><p>Bactericidal materials gained interest in the health care sector as they are capable of preventing material surfaces from microbial colonization and subsequent spread of infections. However, commercialization of antimicrobial materials requires proof of their efficacy, which is usually done using <i>in vitro</i> methods. The ISO 22196 standard (Japanese test method JIS Z 2801) is a method for measuring the antibacterial activity of daily goods. As it was found reliable for testing the biocidal activity of antimicrobially active materials and surface coatings most of the laboratories participating in this study used this protocol. Therefore, a round robin test for evaluating antimicrobially active biomaterials had to be established. To our knowledge, this is the first report on inaugurating a round robin test for the ISO 22196 / JIS Z 2801. The first round of testing showed that analyses in the different laboratories yielded different results, especially for materials with intermediate antibacterial effects distinctly different efficacies were noted. Scrutinizing the protocols used by the different participants and identifying the factors influencing the test outcomes the approach was unified. Four critical factors influencing the outcome of antibacterial testing were identified in a series of experiments: (1) incubation time, (2) bacteria starting concentration, (3) physiological state of bacteria (stationary or exponential phase of growth), and (4) nutrient concentration. To our knowledge, this is the first time these parameters have been analyzed for their effect on the outcome of testing according to ISO 22196 / JIS Z 2801. In conclusion, to enable assessment of the results obtained it is necessary to evaluate these single parameters in the test protocol carefully. Furthermore, uniform and robust definitions of the terms antibacterial efficacy / activity, bacteriostatic effects, and bactericidal action need to be agreed upon to simplify communication of results and also regulate expectations regarding antimicrobial tests, outcomes, and materials.</p></div

Summary of the results for antibacterial testing of the compounds in different laboratories.

<p>Summary of the results for antibacterial testing of the compounds in different laboratories.</p

Summary of material surface characterization for the compounds.

<p>Summary of material surface characterization for the compounds.</p

Description of alternative test methods used in the study.

<p>Description of alternative test methods used in the study.</p

Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801 - Fig 1

<p>Testing of the effect of compound 1 and 3 on <i>E</i>. <i>coli</i> subject to incubation time (a) and calculation of the resulting R values according to ISO 22196 / JIS Z 2801 (b). Data is given as mean ± standard deviation. Note that the R values were calculated to the growth controls at the respective time points to avoid bias.</p

Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801 - Fig 5

<p>AFM measurements of the PA6 control (a), compound 1 (b) and compound 3 (c). Surface roughness is depicted in a range from 0 to 400 nm. The scale bar determines a length of 2 μm.</p

General information on test conditions according to ISO 22196:2011/ JIS Z 2801:2012 and deviations from the standard protocol.

<p>General information on test conditions according to ISO 22196:2011/ JIS Z 2801:2012 and deviations from the standard protocol.</p