. 2018 Nov 19;9:2702. doi: 10.3389/fmicb.2018.02702

Table 1.

Culture media, incubation conditions and results of bacterial counts in wheatmeal used as feed, fresh mealworm larvae and frass of the three pooled rearing batches.

Growth medium	Presumptive microorganism	Growth conditions	Plating method	Reference	Organic wheatmeal	Mealworm larvae	Frass
					log cfu g⁻¹
PCA	Aerobic mesophilic bacteria	30°C;48 h	Pour	(American Public Health Association, 1976)	1.5 ± 0.08 ^c	9.3 ± 0.04^a	7.8 ± 0.01^b
	Spore forming bacteria				<1^c	2.3 ± 0.03 ^b	4.1 ± 0.02^a
MRS	Lactic acid bacteria	30°C;48–72 h	Pour	(De Man et al., 1960)	1.9 ± 0.08^c	8.3 ± 0.01^a	5.8 ± 0.01^b
MRS + ampicillin (8 mg L⁻¹)^*	Ampicillin resistant lactic acid bacteria				<1^c	2.2 ± 0.04^a	1.7 ± 0.05^b
MRS + vancomycin (8 mg L⁻¹) ^*	Vancomycin resistant lactic acid bacteria				1.3 ± 0.03 ^c	7.1 ± 0.01^a	3.9 ± 0.01^b
ESA	Enterococci	37°C;24–48 h	Spread	(Slanetz and Bartley, 1957)	1.6 ± 0.07 ^c	7.9 ± 0.01^a	6.7 ± 0.03^b
ESA + ampicillin (8 mg L⁻¹) ^*	Ampicillin resistant enterococci				<1^a	<1^a	<1^a
ESA + gentamicin (128 mg L⁻¹) ^*	HLAR enterococci				<1^a	<1^a	<1^a
ESA + vancomycin (4 mg L⁻¹) ^*	Vancomycin resistant enterococci				<1^c	5.7 ± 0.03^a	2.6 ± 0.01^b
MSA	Staphylococci	37°C;24–48 h	Spread	(Chapman, 1945; Bannerman, 2003)	<1^b	5.8 ± 0.01^a	5.4 ± 0.01^a
MSA + gentamicin (1 mg L⁻¹) ^*	Gentamicin resistant staphylococci				<1^b	5.7 ± 0.01^a	5.3 ± 0.01^a
MSA + erythromycin (2 mg L⁻¹) ^*	Erythromycin resistant staphylococci				<1^c	4.9 ± 0.04^a	2.8 ± 0.10^b
MSA + tetracycline (2 mg L⁻¹)^*	Tetracycline resistant staphylococci				<1^c	5.2 ± 0.01^a	4.6 ± 0.01^b
MSA + vancomycin (2 mg L⁻¹) ^*	Vancomycin resistant coagulase positive staphylococci				<1^b	4.1 ± 0.04^a	4.3 ± 0.01^a
MSA + vancomycin (4 mg L⁻¹) ^*	Vancomycin resistant coagulase negative staphylococci				<1^c	3.8 ± 0.01^b	4.3 ± 0.09^a
VRBGA	Enterobacteriaceae	37°C;24 h	Pour	(American Public Health Association, 1976)	<1^c	7.5 ± 0.01^a	5.8 ± 0.01^b
VRBGA + ampicillin (8 mg L⁻¹) ^*	Ampicillin resistant Enterobacteriaceae				<1^c	6.1 ± 0.01 ^a	5.0 ± 0.01 ^b
VRBGA + gentamicin (4 mg L⁻¹) ^*	Gentamicin resistant Enterobacteriaceae				<1^c	2.5 ± 0.01^a	1.2 ± 0.20^b
PAB	Pseudomonadaceae	30°C;24–48 h	Spread	(Geftic et al., 1979)	1.0 ±0.00^b	6.7 ± 0.03^a	6.1 ± 0.02^a
PAB + gentamicin (4 mg L⁻¹) ^*	Gentamicin resistant Pseudomonadaceae				<1^c	5.7 ± 0.03^a	3.2 ± 0.01^b

PCA, Plate Count Agar; MRS, de Man Rogosa Sharpe agar; ESA, Enterococcus Selective Agar, MSA, Mannitol Salt Agar; VRBGA, Violet Red Bile Glucose Agar; PAB, Pseudomonas Agar Base; HLAR, High-Level Aminoglycoside Resistance

the breakpoint values defined by European Committee on Antimicrobial Susceptibility Testing (EUCAST, 2017)

Results of bacterial counts are expressed as mean values ± standard deviation of three independent experiments (one for each batch)

Means followed by different letters are significantly different (P < 0.05).