Showing papers by "Frederik Hammes published in 2020"

360-Degree Distribution of Biofilm Quantity and Community in an Operational Unchlorinated Drinking Water Distribution Pipe.

Abstract: In the present study, triplicate rings of 360° pipe surfaces of an operational drinking water distribution pipe were swabbed. Each ring was equally divided into 16 parts for swabbing. The collected swabs were grouped into 3 sections and compared with the biofilm samples sampled by sonication of specimens from the same pipe. The results showed that the biofilm is unevenly distributed over the 16 parts and the 3 sections of the pipe surface. Both the active biomass and the number of observed OTUs increased as the measurements proceeded from the top to the bottom of the pipe. The bacterial community was dominated in all sections by Proteobacteria. At the genus level, Nitrospira spp., Terrimonas spp., and Hyphomicrobium spp. were dominant in all sections. Gaiella spp. and Vicinamibacter spp. dominated in S-I, Blastopirellula spp. and Pirellula spp. dominated in S-II, while Holophaga spp. and Phaeodactylibacter spp. dominated in S-III. When swabbing and pipe specimen sonication were compared, the results showed that the sampling strategy significantly influences the obtained biofilm bacterial community. A consistent multisectional swabbing strategy is proposed for future biofilm sampling; it involves collecting swabs from all sections and comparing the swabs from the same position/section across locations.

Feeding the building plumbing microbiome: The importance of synthetic polymeric materials for biofilm formation and management

Abstract: The environmental conditions in building plumbing systems differ considerably from the larger distribution system and, as a consequence, uncontrolled changes in the drinking water microbiome through selective growth can occur In this regard, synthetic polymeric plumbing materials are of particular relevance, since they leach assimilable organic carbon that can be utilized for bacterial growth Here, we discuss the complexity of building plumbing in relation to microbial ecology, especially in the context of low-quality synthetic polymeric materials (ie, plastics) and highlight the major knowledge gaps in the field We furthermore show how knowledge on the interaction between material properties (eg, carbon migration) and microbiology (eg, growth rate) allows for the quantification of initial biofilm development in buildings Hence, research towards a comprehensive understanding of these processes and interactions will enable the implementation of knowledge-based management strategies We argue that the exclusive use of high-quality materials in new building plumbing systems poses a straightforward strategy towards managing the building plumbing microbiome This can be achieved through comprehensive material testing and knowledge sharing between all stakeholders including architects, planners, plumbers, material producers, home owners, and scientists

Towards a probiotic approach for building plumbing – nutrient-based selection during initial biofilm formation on flexible polymeric materials

Abstract: Upon entering building plumbing systems, drinking water bacteria experience considerable changes in environmental conditions. For example, some flexible polymeric materials leach organic carbon, which increases bacterial growth and reduces diversity. Here we show that the carbon supply by a flexible polymeric material drives nutrient-based selection within establishing biofilm communities. We found that migrating carbon from EPDM coupons resulted in considerable growth for different drinking water communities (0.2 – 3.3 × 108 cells/cm2). All established biofilm communities showed low diversity (29 – 50 taxa/biofilm), with communities dominated by even viewer taxa (e.g., 5 taxa accounting for 94 ± 5 % relative abundance, n = 15). Interestingly, biofilm communities shared some taxa (e.g., Methylobacterium spp.) and families (e.g., Comamonadaceae), despite the difference in starting communities. Moreover, selected biofilm communities performed better than their original communities regarding maximum attachment (91 ± 5 vs. 69 ± 23 %, n = 15) and attachment rate (5.0 ± 1.7 × 104 vs. 2.4 ± 1.2 × 104 cells/cm2/h, n = 15) when exposed to new EPDM coupons. Our results demonstrate nutrient-based selection during initial biofilm formation on a flexible polymeric material and a resulting benefit to selected communities. We anticipate our findings to help connecting observational microbiological findings with their underlying ecological principles. Regarding initial biofilm formation, attachment dynamics, growth, and selection thereof are important for the management of microbial communities. In fact, managing initial colonization by supplying specific carbon and/or introducing consciously chosen/designed communities potentially paves the way for a probiotic approach for building plumbing materials.