The amount of lipids corresponding to tiny droplets was quantified using a colorimetric method for measuring the triacylglycerol content (Triglycerides Liquicolor Mono kit, HUMAN). In brief, the subnatant samples, obtained as described in the section above, were diluted to a range of 0.4-4 g/L, and about 20 µL of the sample was weighed into a 2-mL microcentrifuge tube. Next, 1 mL of assay reagent was added, and the samples were subsequently incubated in a heating block at 800 rpm for 20 min at 20 °C. The absorbance was measured at a wavelength of 500 nm, and the concentration was calculated using a calibration curve (0.4-4 g triglycerides/L).