Saccharomyces cerevisiae expressing bacteriophage endolysins reduce Lactobacillus contamination during fermentation

Khatibi, Piyum A; Roach, Dwayne R; Donovan, David M; Hughes, Stephen R; Bischoff, Kenneth M

doi:10.1186/1754-6834-7-104

Biotechnology for Biofuels and Bioproducts

Table 1 Lactic acid, acetic acid, and ethanol concentrations over 72 h from experimentally infected fermentations

From: Saccharomyces cerevisiae expressing bacteriophage endolysins reduce Lactobacillus contamination during fermentation

Treatment and yeast variant¹		N	Lactic acid²				Acetic acid²				Ethanol²
			(mg/mL ± SEM)				(mg/mL ± SEM)				(mg/mL ± SEM)
			0 h	24 h	48 h	72 h	0 h	24 h	48 h	72 h	0 h	24 h	48 h	72 h
Induced	LysA	4	0.1^a ± 0.0	0.4^b ± 0.2	1.9^b ± 0.7	2.7^bc ± 1.0	0.2^a ± 0.0	1.0^bc ± 0.2	2.1^cd ± 0.4	2.8^bc ± 0.6	2.8^a ± 0.8	22.0^a ± 3.5	36.5^a ± 2.6	45.4^a ± 2.7
	LysA2	4	0.1^a ± 0.0	0.1^b ± 0.0	0.5^c ± 0.3	1.7^cd ± 0.6	0.1^a ± 0.0	0.6^c ± 0.1	1.4^de ± 0.2	1.9^cd ± 0.4	2.6^a ± 0.6	18.0^a ± 4.4	35.7^a ± 6.6	41.2^ab ± 7.9
	Untransformed	4	0.1^a ± 0.0	0.9^b ± 0.5	2.7^b ± 0.4	3.4^b ± 0.5	0.1^a ± 0.0	1.3^b ± 0.3	2.5^bc ±0.3	3.0^b ± 0.3	3.0^a ± 0.4	23.6^a ± 3.3	36.9^a ± 5.1	41.5^ab ± 6.6
Induced and yeast lysate-treated (BB)	LysA	4	0.1^a ± 0.0	0.1^b ± 0.0	0.1^c ± 0.0	0.1^d ± 0.0	0.1^a ± 0.0	0.8^bc ± 0.2	1.1^e ± 0.2	1.3^de ± 0.3	3.3^a ± 0.7	22.3^a ± 3.8	36.9^a ± 5.2	46.2^a ± 7.0
	LysA2	4	0.1^a ± 0.0	0.1^b ± 0.0	0.1^c ± 0.0	0.1^d ± 0.0	0.1^a ± 0.0	0.7^bc ± 0.1	0.9^e ± 0.2	1.0^e ± 0.2	2.9^a ± 0.8	20.2^a ± 4.6	29.9^ab ± 5.2	34.1^ab ± 5.3
	Untransformed	3	0.1^a ± 0.0	0.3^b ± 0.2	2.1^b ± 0.2	3.7^b ± 0.6	0.1^a ± 0.0	0.9^bc ± 0.1	2.1^cd ± 0.2	2.9^bc ± 0.1	2.4^a ± 0.5	17.1^a ± 2.8	29.4^ab ± 4.3	37.4^ab ± 6.0
Non-induced	LysA	3	0.1^a ± 0.0	3.3^a ± 0.7	4.8^a ± 0.8	6.5^a ± 0.8	0.1^a ± 0.0	2.1^a ± 0.4	3.2^ab ± 0.4	4.3^a ± 0.4	2.5^a ± 1.0	15.4^a ± 2.4	21.0^b ± 2.8	24.5^b ± 2.7
	LysA2	3	0.1^a ± 0.0	3.1^a ± 0.5	5.5^a ± 0.6	6.4^a ± 0.8	0.1^a ± 0.0	2.2^a ± 0.1	3.7^a ± 0.1	4.4^a ± 0.2	2.3^a ± 0.2	19.3^a ± 2.1	30.2^ab ± 3.5	33.4^ab ± 4.1
	Untransformed	4	0.1^a ± 0.0	2.9^a ± 0.2	4.4^a ± 0.6	6.1^a ± 0.6	0.2^a ± 0.1	2.0^a ± 0.1	3.0^ab ± 0.2	4.1^a ± 0.3	2.8^a ± 0.3	24.0^a ± 1.2	31.5^ab ± 0.7	35.6^ab ± 2.7

¹Fermentations were conducted using S. cerevisiae strain BY4727. Induced fermentations contained 10% galactose, while non-induced fermentations were supplemented with deionized water. Experimentally infected fermentations were inoculated at time zero with 5 log₁₀ (CFU/mL) L. fermentum 0605-B44. To prepare a yeast lysate containing LysA or LysA2, 10% of the fermentation volume was removed at 0 h and 0.5 h and was mechanically lysed (bead beating; BB) for five rounds of 30 s followed by 30 s on ice and returned to the fermentation.
²Concentrations (mg/mL ± SEM) of ethanol, lactic acid, and acetic acid with different superscript letters within a column are significantly different (P < 0.05) from each other using Student’s t-test.

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