Seasonal Dynamics in the Number and Composition of Coliform Bacteria in Drinking Water Reservoirs

Abstract

Worldwide, surface waters like lakes and reservoirs are one of the major sources for drinking water production, especially in regions with water scarcity. In the last decades, they have undergone significant changes due to climate change. This includes not only an increase of the water temperature but also microbiological changes. In recent years, increased numbers of coliform bacteria have been observed in these surface waters. In our monitoring study we analyzed two drinking water reservoirs (Klingenberg and Kleine Kinzig Reservoir) over a two-year period in 2018 and 2019. We detected high numbers of coliform bacteria up to 2.4 x 10^4 bacteria per 100 ml during summer months, representing an increase of four orders of magnitude compared to winter. Diversity decreased to one or two species that dominated the entire water body, namely Enterobacter asburiae and Lelliottia spp., depending on the reservoir. Interestingly, the same, very closely related strains have been found in several reservoirs from different regions. Fecal indicator bacteria Escherichia coli and enterococci could only be detected in low concentrations. Furthermore, fecal marker genes were not detected in the reservoir, indicating that high concentrations of coliform bacteria were not due to fecal contamination. Microbial community revealed Frankiales and Burkholderiales as dominant orders. Enterobacterales, however, only had a frequency of 0.04% within the microbial community, which is not significantly affected by the extreme change in coliform bacteria number. Redundancy analysis revealed water temperature, oxygen as well as nutrients and metals (phosphate, manganese) as factors affecting the dominant species. We conclude that this sudden increase of coliform bacteria is an autochthonic process that can be considered as a mass proliferation or ‘coliform bloom’ within the reservoir. It is correlated to higher water temperatures in summer and is therefore expected to occur more frequently in the near future, challenging drinking water production.

Penggunaan H2O2 (Hidrogen Peroksida) untuk Mengurangi Kadar Coliform Air Pada Peternakan Ayam Petelur di Kabupaten Blitar

“…Hidrogen Peroksida mampu menekan jumlah coliform air pada peternakan ayam petelur di desa kawedusan Ponggok Blitar pada tandon C. Hidrogen peroksida merupakan desinfektan yang ramah lingkungan dan tidak berpengaruh terhadap kesehatan manusia (Ciriminna, et al,2016). Peningkatan total coliform di dalam air merupakan proses proliferasi di dalam reservoir (Reitter, et al,2021). Pentingnya memilih penggunaan desinfektan yang sesuai dengan konsentrasi sebagai pembersih air yang akan membunuh coliform daripada pemilihan desinfektan yang hanya menyebabkan penghambatan sel bakteri sehingga dapat diinduksi yang menghasilkan pemulihan dari bakteri coliform (Izumi, et al,2016).…”

Draft Genome Sequences of Enterobacter spp., Lelliottia spp., and Serratia spp., Coliform Bacteria from Drinking Water Reservoirs and Lakes

“…forming “coliform blooms,” whereas Serratia spp. dominate in winter ( 1 – 3 ). As coliform bacteria occasionally overcome treatment and reach drinking water, further research is needed with regard to their hygienic relevance and their capability to proliferate in these oligotrophic environments ( 3 ).…”

“…dominate in winter ( 1 – 3 ). As coliform bacteria occasionally overcome treatment and reach drinking water, further research is needed with regard to their hygienic relevance and their capability to proliferate in these oligotrophic environments ( 3 ). Traditionally regarded as fecal indicator bacteria, coliform bacteria also occur naturally in water, plants, and soil ( 4 – 6 ).…”