However, these studies often lacked a strong microbiological foundation and comparisons to standard techniques. Several studies have investigated the use of microbiological testing during field assessments and in low-resource settings ( 10– 14), employing products such as Petrifilms™ (3M™).

To minimize temporal degradation, environmental samples would ideally be processed as soon as they are collected. Therefore, any evaluation of microbiological water quality in areas that lack repeat sampling and long-term monitoring is considered to be only a snapshot of bacterial loads from that sampling location at that particular time ( 1). Guidelines often specify values for both the geometric mean of all samples and a single-sample maximum to account for the heterogeneous nature of water bodies ( 1, 7, 9). Regulatory guidelines outline both the frequency of sampling and the minimum number of samples that should be collected for a given recreational area, allowing for only a limited regional inference. Many monitoring programs for recreational areas sample on a daily or weekly basis ( 1, 8), however, these sampling and monitoring programs come at a large expense and are typically limited in geographic scope. It is widely accepted when testing for many common indicator organisms that samples processed more than 24 h after collection poorly represent bacterial loads at the time of collection and make for inconsistent and unreliable results that can lead to inaccurate conclusions ( 1, 7). Various regulatory agencies indicate that samples for microbiological analysis should be processed within 24 h of collection, or up to 48 h for samples from remote locations, with the minimum holding time possible being preferred (ideally <8 h) ( 1– 6). The viability of microbial cells can change drastically and inconsistently over time after collection of samples and this can lead to underestimation of microbial loads and results that do not accurately reflect the original sampled location ( 1– 3). Furthermore, the timely arrival of samples to testing laboratories is critical so that the microbial community in the sample changes minimally during transit ( 1– 3). Microbiological analyses typically require a well-equipped laboratory with specialized equipment and expertise. Monitoring programs are in place for drinking water, wastewater, and for recreational beaches, but studying bacterial contamination in more remote locations poses many challenges ( 1). Surveillance and monitoring of bacterial contamination in aquatic environments is critical for public health for water recreation, consumption, and sanitation ( 1). Our incubator design can be easily adapted for a wide variety of researcher goals and represents a robust platform for field studies and other applications, including those in remote or low-resources settings. To the best of our knowledge, this is the largest bacteriological water quality assessment of freshwater lakes to date in terms of both spatial scale and the number of lakes sampled. coli was not frequently detected, but many lakes exceeded Canadian guideline values for activities such as swimming and some even exceeded the guideline value for secondary recreational activities such as boating. We found higher loads at the shoreline than the middle of lakes and different patterns between ecozones.

Using this method, thermotolerant coliforms (TTCs) and Escherichia coli were quantified from 432 lakes, allowing comparison to both historical datasets that relied on TTCs and those following current guidelines that use E. Bacterial counts were also found to be statistically equivalent to counts obtained with standard laboratory techniques using a conventional incubator. Samples from all sites were processed in duplicate and bacterial counts were highly repeatable within and across sampling teams. Rigorous testing and validation of our incubators ensured that incubation conditions were consistent within and across all 10 field teams and 2 sampling years. We developed and constructed rugged, reliable, and cost-effective portable incubators that were used by 10 independent field teams to perform microbiological assays on surface water samples from lakes across Canada. For example, the viability of some bacteria can decrease greatly between sampling and arrival to the laboratory for processing.

Performing microbiological assays on environmental samples in field settings poses logistical challenges with respect to the availability of suitable equipment or the ability to get samples to the laboratory in a timely fashion.

Lab incubator