The authors cultivated and observed extremely small populations of bacteria over an extended period of time. In this study specifically, the authors were able to study and monitor individual cells and their growth dynamics.

After cleaning the segment with lysis buffer to remove wall-adhering cells, the segment must then be flushed with sterile growth medium in order to remove any remaining buffer. This is important as it allows the authors to maintain a constant environment within the segment.

A microchemostat is a type of bioreactor that maintains a continuous culture of microorganisms under controlled conditions. This was used throughout the experiment and allowed the authors to study the microbial populations and their dynamics in a controlled environment.

Learning Standard (Table 10-1 Section 2)

Learning is defined as the combination of both knowledge and practice, not separate content and process learning goals: Core ideas in the framework are specified not as explanations to be consumed by learners. The performances combine core ideas and practices. The practices include several methods for generating and using evidence to develop, refine, and apply scientific explanations to construct accounts of scientific phenomena. Students learn and demonstrate proficiency with core ideas by engaging in these knowledge-building practices to explain and make scientifically informed decisions about the world.

Engineered bacteria with a synthetic population control circuit are used to study the growth and behavior of bacterial populations in controlled environments.

The microchemostat was primarily operated in the continuous circulation mode, but it required cleaning and dilution to remove any cells adhering to the walls. During the cleaning and dilution process, mixing is stopped and the segment is isolated from the rest of the reactor and cleaned.

Biofilms impacted the performance of the bioreactor, leading to a decrease in its efficiency.

Multiple types of passive treatment such as polyethylene glycol, ethylenediaminetetraacetic acid, polyoxyethylene sorbitan monolaurate, and bovine serum albumin were tested to see if they would prevent biofilm formation. These surface coatings were used as a passive treatment, or a treatment in which the authors would not need to actively intervene. After testing, none of the treatments proved to be effective and the authors decided they had to "actively" kill the bacteria to prevent biofilm formation.

Nutrient-rich environments allow for rapid growth of bacterial cultures. This is due to the fact that nutrient-rich environments provide many different types of organic and inorganic compounds which bacteria use as a source of energy.

Temperature growth can have a significant impact on bacterial growth. Optimal temperature allows for the metabolic processes within bacteria to perform at an effective rate, allowing for an increase in bacterial growth. When the temperature of growth medium is below or above optimal, bacterial growth decreases and cell death may occur.

Please check out the following video on engineered bacteria and synthetic genetic circuits: Syntheic Biology: Programming Living Bacteria - Christopher Voigt https://youtu.be/lNttxYdGHs4

Sterile medium is a growth medium which is free of all life forms. This was used to measure cell growth from zero cell growth.

The authors aimed for a consistent environment with fixed temperature and consistent nutrient levels to conduct a controlled study. This approach enabled them to observe cell growth while maintaining a stable environmental condition.

The process of flushing the fluidic channels and replacing the once existing biofilms with sterile medium is used by the authors to allow the bioreactor function properly. Flushing these fluidic channels must be performed actively, as the passive approached showed no effect on removing biofilms.

Wall-adhering cells are cells that grow directly on the sides or walls of the chamber they are growing in. Wall-adhering cells create biofilms and the authors use a lysis buffer to flush these cells. At which point the sterile medium is then reconnected with the growth chamber.

Inoculation is the process of introducing something into an environment suitable for growth. Inoculation was used to add E.coli MG1655 cells to five different chips.

Learning Standard (K.MD)

Describe and compare measurable attributes. The authors used measurements to compare cell density and morphology throughout the experiment.

Learning Standard (7.SP)

Use random sampling to draw inferences about a population. The authors isolated a segment from the bioreactor to further measure and study the cells within it.

Learning Standard (K.MD)

Describe and compare measurable attributes. The authors used measurements to compare the oscillations seen in cell growth throughout time.

Learning Standard (W.7)

Conduct research projects to answer questions. The authors use six experiments to receive accurate data.