Enhancement of lignocellulosic degradation in high-moisture alfalfa via anaerobic bioprocess of engineered Lactococcus lactis with the function of secreting cellulase

Liu, Qinhua; Li, Junfeng; Zhao, Jie; Wu, Jingxing; Shao, Tao

doi:10.1186/s13068-019-1429-4

Biotechnology for Biofuels and Bioproducts

Table 2 Fermentative characteristics of high-moisture alfalfa silages after ensiling

From: Enhancement of lignocellulosic degradation in high-moisture alfalfa via anaerobic bioprocess of engineered Lactococcus lactis with the function of secreting cellulase

Items	Additives	Time (days)				SEM	Significance
Items	Additives	1	6	18	60	SEM	Additives	Time	Additives × time
pH	Control	5.80^aA	4.57^aB	4.39^aB	5.35^aA	0.059	< 0.001	< 0.001	< 0.001
	EN	5.80^aA	4.42^abC	4.17^bcD	4.62^bB
	HT1	4.95^cB	4.42^abC	4.32^abC	5.22^aA
	HT1 + EN	5.23^bA	4.40^abB	4.29^abcC	4.47^bB
	HT2	4.76^dA	4.20^bC	4.12^cC	4.49^bB
Lactic acid (g/kg DM)	Control	8.67^bB	40.1^bA	41.1^bA	16.3^bB	2.914	< 0.001	< 0.001	< 0.001
	EN	10.3^bC	45.2^abAB	56.6^aA	33.8^bB
	HT1	16.4^aC	40.3^bB	49.4^abA	18.3^bC
	HT1 + EN	16.1^aC	52.5^aB	50.1^abB	69.0^aA
	HT2	17.4^aD	41.9^bC	58.2^aB	67.1^aA
Acetic acid (g/kg DM)	Control	12.0^aC	22.8^abBC	32.4^abAB	42.5^bA	3.027	< 0.001	< 0.001	< 0.001
	EN	12.2^aC	24.8^aBC	33.6^aB	79.2^aA
	HT1	2.10^bC	16.0^bcBC	24.6^bB	46.2^bA
	HT1 + EN	5.09^bD	19.0^abC	30.9^abB	39.9^bA
	HT2	1.70^bD	9.56^cC	24.3^bB	32.4^bA
Propionic acid (g/kg DM)	Control	0.19	0.00	0.00	5.69	1.028	0.150	0.011	0.110
	EN	0.00	0.00	0.00	0.00
	HT1	0.00^B	0.00^B	0.00^B	3.79^A
	HT1 + EN	0.00	0.00	0.00	0.00
	HT2	0.00	0.00	0.00	0.00
Butyric acid (g/kg DM)	Control	0.00^B	0.00^B	0.59^B	36.94^aA	2.700	< 0.001	< 0.001	< 0.001
	EN	0.00	0.00	0.00	0.00
	HT1	0.00B	0.00B	0.00B	29.89^aA
	HT1 + EN	0.00	0.00	0.00	0.00^b
	HT2	0.00	0.00	0.00	0.00^b
Ammonia-N (g/kg N)	Control	50.2^aB	103^aB	113^aB	246^aA	11.49	< 0.001	< 0.001	< 0.001
	EN	48.2^abC	79.2^bB	87.1^bB	129^bA
	HT1	35.6^bcB	65.8^bcB	83.26^bB	210^abA
	HT1 + EN	37.7^abcD	64.7^bcC	91.0^bB	108^bA
	HT2	34.0^cD	51.9^cC	81.1^bB	106^bA
LA/AA	Control	0.74 ^dBC	1.77^bA	1.26^cAB	0.38^bC	0.254	< 0.001	< 0.001	< 0.001
	EN	0.84^dB	1.83^bA	1.68^bcAB	0.44^bC
	HT1	7.84^bA	2.64^bB	2.04^abBC	0.43^bC
	HT1 + EN	3.16^cA	2.81^bA	1.65^bcB	1.75^aB
	HT2	10.33 aA	4.40 aB	2.39 aC	2.08^aC
V-score	Control	99.6^abA	85.9^cA	79.8^bA	38.2^bcB	2.519	< 0.001	< 0.001	< 0.001
	EN	99.5^bA	91.7^bB	87.9^aB	68.8^abC
	HT1	100^aA	95.6^abAB	88.8^aB	36.5^cC
	HT1 + EN	100^aA	95.4^abA	88.3^aB	79.7^aC
	HT2	100^aA	99.5^aA	91.7^aB	83.6^aC

Values with different superscript lowercase letters show significant differences among treatments in the same ensiling day, values with different superscript capital letters show significant differences among ensiling days in the same treatment (P < 0.05) according to Tukey’s test
Control, silage treated without additives; DM, dry matter; EN, cellulase; HT1, wild-type L. lactis subsp. lactis MG1363; HT1 + EN, combination of HT1 and EN; HT2, combination of transgenically engineered L. lactis strains HT1/pMG36e-usp45-bgl1, HT1/pMG36e-usp45-cbh2, and HT1/pMG36e-usp45-egl3; N, nitrogen; LA/AA, ratio of lactic acid to acetic acid; SEM, standard error of the means

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ISSN: 2731-3654

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