Rapid sample processing for intracellular metabolite studies in Penicillium ochrochloron CBS 123.824: the FiltRes-device combines cold filtration of methanol quenched biomass with resuspension in extraction solution

Table 1 Overview of performed glucose-limited chemostat cultivations (µ = 0.1^−h, 30 °C, pH 7), sampling time points, applied FiltRes-prototype and other variations in sample protocols in course of the method development

Chemostat	General		Variations in experimental protocol
Chemostat	Bioreactor	Sampling time point (h)	FiltRes prototype	Washing steps	Extraction solvent	Analytical procedure
I	BB	64^TB	GL	0^b	50 % (v/v) ethanol	IN
II	BM	116^TB	GL	0^b	50 % (v/v) ethanol	IN
III	BB	80^TB	GL	0^b, 1^b, 2^a and 3^b	50 % (v/v) ethanol	IM
			POM	1^c	50 % (v/v) ethanol	IM
IV	BB	90	GL	0^e	50 % (v/v) ethanol	IM
V	BM	53^TB	M	0^a	50 % (v/v) ethanol	IM
VI	BM	42	POM	0^b and 1^a	50 % (v/v) ethanol	IM
		73	POM	0^b	50 % (v/v) ethanol	IM
		88^TB	POM	0^b and 1^b	50 % (v/v) ethanol	IM
VII	BM	69	POM	1^b	50 % (v/v) ethanol	IM
VIII	BM	47	POM	0^c	Buffered 50 % (v/v) ethanol	F
		67	POM	0^d	Buffered 50 % (v/v) ethanol	F
		92	POM	0^d	Buffered 50 % (v/v) ethanol	F

Bioreactor (working volume): BM, Biostat M (1.8 L); BB, Biostat B (4 L)
FiltRes-prototypes: GL, prototype with GL 45 cap; M, prototype made of metal; POM, prototype made of polyoxymethylene (details see “Methods” and Additional file 1: Fig. S1)
Analytical procedure: IN, initial method after Ganzera et al. (2006); IM, intermediary method after Krüger (2013); F, final method after Krüger (2013), for details see “Methods”
Number of samples: ^a n = 2, ^b n = 3, ^c n = 4, ^d n = 5, ^e n = 6
^TB At these sampling time points also heat stopped total broth samples were taken as reference samples (details see “Methods”)