Microtiter Plate Assay for Assessment of Listeria monocytogenes Biofilm Formation

Abstract

Listeria monocytogenes has the ability to form biofilms on food-processing surfaces, potentially leading to food product contamination. The objective of this research was to standardize a polyvinyl chloride (PVC) microtiter plate assay to compare the ability of L. monocytogenes strains to form biofilms. A total of 31 coded L. monocytogenes strains were grown in defined medium (modified Welshimer's broth) at 32°C for 20 and 40 h in PVC microtiter plate wells. Biofilm formation was indirectly assessed by staining with 1% crystal violet and measuring crystal violet absorbance, using destaining solution. Cellular growth rates and final cell densities did not correlate with biofilm formation, indicating that differences in biofilm formation under the same environmental conditions were not due to growth rate differences. The mean biofilm production of lineage I strains was significantly greater than that observed for lineage II and lineage III strains. The results from the standardized microtiter plate biofilm assay were also compared to biofilm formation on PVC and stainless steel as assayed by quantitative epifluorescence microscopy. Results showed similar trends for the microscopic and microtiter plate assays, indicating that the PVC microtiter plate assay can be used as a rapid, simple method to screen for differences in biofilm production between strains or growth conditions prior to performing labor-intensive microscopic analyses.

Identification of Components of the SUMOylation Machinery in Candida glabrata

“…Biofilm Assay-The ability of C. glabrata cells to produce biofilms on polystyrene-coated plates was assessed as described previously (52). One ml of the YPD-grown logarithmic culture (1 ϫ 10 5 cells in PBS) was added to a well of the polystyrenecoated 24-well plate and incubated at 37°C for 90 min.…”

Phenotype switching affects biofilm formation by Candida parapsilosis

“…The cells were allowed to adhere for 2 h and wells were washed twice with PBS to remove non-adhered cells; 100 ml fresh growth medium then was added to the wells and the plates were returned to the incubator for 48 h. To determine the effect of farnesol, cells were incubated in YPD medium containing 8 % glucose supplemented with 30 or 300 mM trans,trans-farnesol (Sigma). After 12-60 h, the wells were washed twice with 200 ml PBS and biofilm mass was measured by using a crystal violet assay (Djordjevic et al, 2002). Each of the washed wells was stained by adding 100 ml 0?1 % aqueous crystal violet solution and incubating at 30 uC for 15 min.…”

Biossurfactantes: propriedades anticorrosivas, antibiofilmes e antimicrobianas

“…Por outro lado, pode ser um dos fatores envolvidos na aderência inicial dos micro-organismos às superfícies. 10,20 Quanto maior a hidrofobicidade das superfícies envolvidas na formação do biofilme, maior será a formação deste. 21 A hidrofobicidade bacteriana pode variar muito entre diferentes linhagens de mesmos micro-organismos.…”

“…20 Esta resistência das células do biofilme às influências externas como antibióticos, defesas do hospedeiro, antissépticos e forças de cisalhamento, é uma preocupação constante nas indústrias e na medicina. 6 Existem três mecanismos usualmente aceitos que justificam a resistência maior dos micro-organismos presentes nos biofilmes, são eles: a capacidade do EPS impedir o contato do agente com os micro-organismos, funcionando como um filtro; os micro-organismos apresentarem um estado metabólico diferenciado (metabolismo mais lento) e a capacidade de modificar e/ou neutralizar o agente (principalmente em biofilmes com mais de uma espécie).…”