Table 2.

Guidelines followed in this study to reduce plastic waste

Reuse of single-use items
Weighing boats	Washed, dried and reused
Plastic serological pipettes	For pipetting common non-sterile solutions (e.g. ethanol, concentrated buffered solutions). Sheathed in their plastic wrap, labelled with the working solution that they were used for, and attached to the cupboard near the pipette controller
Cuvettes	Decontaminated overnight in 10 % Distel, rinsed with water, dried and reused
Tip-collecting jars	Contaminated tips transferred to biohazard bins when full. Chemically decontaminate the jar overnight when necessary
Petri dishes	Petri dishes used in cell culture room with media only are decontaminated, washed and reused for agar media with antibiotics
Decontaminate and autoclave Falcon tubes
Used 15 ml and 50 ml Falcon tubes	Chemically decontaminated overnight, rinsed with water, washed in a dishwasher with a water-only programme, autoclaved in bags. Tubes are closed in a cell culture hood and considered sterile for non-cell culture work. We stopped using universal tubes since they cannot be autoclaved for reuse. Control: tested for contaminations. None so far
Substitution of single-use items with re-usable ones
Single-use	Replace by
Plastic inoculation loops	Metal inoculation loops
Plastic tips for bacterial colony picking	Wooden sticks (biodegradable and reused after autoclave)
Training
Plan experiments to reduce single-use items	Prepare master mix to reduce tips  Organize experimental layouts to use the minimum number of tubes and plates  Use 96-well plates instead of Eppendorf’s for serial dilutions in experiments with several dilutions/conditions  Divide the agar plate in parts (more than one condition per plate)  Use lines and drop technique for experiments with bacterial serial dilutions  Use the same tips for the same condition
Non-pyrogenic vs autoclaved lab plastics	When possible use in-house autoclaved tips (with reused tip boxes and without plastic wrapping) instead of filtered tips  For work that does not need to be non-pyrogenic or RNA/DNA-free, use autoclaved tubes (sterile and reused)
Before any protocol step: is there a more sustainable way to do this?

Distel refers to Distel high level laboratory disinfectant (Scientific Lab Supplies).