Investigation of the microbial communities colonizing prepainted steel used for roofing and walling

© 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd. Microbial colonization of prepainted steel, commonly used in roofing applications, impacts their aesthetics, durability, and functionality. Understanding the relevant organisms and the mechanisms by which colonization occurs would provide valuable information that can be subsequently used to design fouling prevention strategies. Here, next-generation sequencing and microbial community finger printing (T-RFLP) were used to study the community composition of microbes colonizing prepainted steel roofing materials at Burrawang, Australia and Kapar, Malaysia over a 52-week period. Community diversity was low and was dominated by Bacillus spp., cyanobacteria, actinobacteria, Cladosporium sp., Epicoccum nigrum, and Teratosphaeriaceae sp. Cultivation-based methods isolated approximately 20 different fungi and bacteria, some of which, such as E. nigrum and Cladosporium sp., were represented in the community sequence data. Fluorescence in situ hybridization imaging showed that fungi were the most dominant organisms present. Analysis of the sequence and T-RFLP data indicated that the microbial communities differed significantly between locations and changed significantly over time. The study demonstrates the utility of molecular ecology tools to identify and characterize microbial communities associated with the fouling of painted steel surfaces and ultimately can enable the targeted development of control strategies based on the dominant species responsible for fouling

Evaluation of hindered amine light stabilisers and their N-chlorinated derivatives as antibacterial and antifungal additives for thermoset surface coatings

© 2016 Elsevier B.V. N-Halogenated amines or ‘halamines’ have attracted recent attention as potential biocides for materials and surface coatings application. Facile N-chlorination of the hindered amine light stabiliser (HALS) Tinuvin®770, bis-(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, was achieved by reaction with sodium dichloroisocyanurate. The chlorinated product was incorporated into a polyester-based paint formulated for coil coating, applied to test panels and subjected to high temperature curing conditions characteristic of the coil coating process (55 s at 262 °C). Rapid detection of N-chlorinated Tinuvin®770 in the cured coating was confirmed, using liquid extraction surface analysis-mass spectrometry, by the characteristic fragmentation patterns of the halamines observed upon collision-induced dissociation. Antimicrobial activity of the coating was determined by testing against the bacterium Pseudomonas aeruginosa and the fungus Cladosporium sp., two organisms that are known to colonise both internal and external surfaces in building and cladding applications. The activity of HALS and halamine containing coatings were compared against a commercial product containing an antimicrobial additive as well as control surfaces without additives. Significant activity against the bacterium, but not against the fungus was demonstrated for the parent HALS and halamine containing coatings. The possibility of regeneration of the halamines was also tested and confirmed by mass spectrometry, post-chlorination of samples showed no significant differences in activity between corresponding pairs of samples