Influence of temperature and pH on the production of biosurfactant, bacteriocin and lactic acid by Lactococcus lactis CECT-4434

Figures & data

Table 1. pH changes as a function of time during Lc. lactis cultures carried out at 30°C, 37°C, and 40°C, with or without pH control.

Tabla 1. Variación del pH a lo largo del tiempo durante el cultivo de Lc. Lactis llevado a cabo a 30, 37 y 40ºC, con y sin control de pH.

	Time (h)	30°C	37°C	40°C
Without pH control	0	5.30	5.30	5.30
	6	4.74	4.71	4.99
	16	4.23	4.25	4.77
	24	4.16	4.20	4.64
With pH control	0	5.30	5.30	5.30
	6	5.11	5.05	5.12
	16	5.10	5.01	5.15
	24	5.21	5.12	5.14

Figure 1. Glucose consumption (•), surface tension reduction (∎), lactic acid production (♦). Runs without pH control at: (a) 30°C, (b) 37°C, and (c) 40°C. Runs with pH control at: (d) 30°C, (e) 37°C, and (f) 40°C.

Figura 1. Consumo de glucosa (•), reducción de tensión superficial (∎), producción de ácido láctico (♦). Ensayos sin control del pH: (a) 30°C, (b) 37°C and (c) 40°C. Ensayos con control del pH: (d) 30°C, (e) 37°C y (f) 40°C.

Table 2. Inhibition zones (mm) of Lactobacillus sakei ATCC 15521 and Staphylococcus aureus CECT-239 growth induced by Lactococcus lactis CECT-4434 bacteriocin produced at different temperatures, with and without pH control.

Tabla 2. Zonas de inhibición de crecimiento (mm) de las cepas Lactobacillus sakei ATCC 15521 y Staphylococcus aureus CECT-239 por la bacteriocina producida por Lactococcus lactis CECT-4434 a diferentes temperaturas, con y sin control de pH.

		L. sakei ATCC 15521*			S. aureus CECT-239*
	Time (h)	30°C	37°C	40°C	30°C	37°C	40°C
Without pH control	6	10.0 ± 0.0^def	9.0 ± 0.0^bc	7.8 ± 0.8^ab	14.0 ± 0.0^l	13.4 ± 0.4^jkl	12.9 ± 0.4^ijkl
	16	9.8 ± 0.3^cdef	9.6 ± 0.2^cde	7.7 ± 0.9^ab	13.0 ± 0.0^hijkl	12.5 ± 0.1^hi	12.0 ± 0.0^gh
	24	9.8 ± 0.3^cdef	9.4 ± 0.1^cd	7.5 ± 0.6^a	13.8 ± 0.2^kl	12.8 ± 0.3^hijk	11.0 ± 0.0^fg
With pH control	6	10.5 ± 0.0^ef	10.0 ± 0.0^cdef	9.6 ± 0.2^cde	14.0 ± 0.0^l	13.1 ± 0.2^ijkl	12.7 ± 0.0^hij
	16	10.6 ± 0.1^ef	10.4 ± 0.0^def	10.0 ± 0.1^def	13.6 ± 0.6^kl	13.0 ± 0.0^hijkl	12.4 ± 0.7^hij
	24	10.4 ± 0.5^ef	10.2 ± 0.0^def	10.0 ± 0.0^cdef	14.0 ± 0.0^l	12.8 ± 0.7^ijkl	13.2 ± 0.1^ijkl

*Mean values (n = 3) ± standard deviation. Different letters show statistically significant difference among the values in the table (P < 0.05).

*Valores medios (n = 3) ± desviación estándar. Diferentes letras muestran diferencias estadísticamente significativas entre los valores de la tabla (P < 0,05).

Table 3. Lactococcus lactis CECT-4434 biomass concentration (g/L) and reduction of surface tension (STred) as a result of biosurfactant production at different temperatures, with and without pH control.

Tabla 3. Concentración de biomasa de Lactococcus lactis CECT-4434 (g L) y reducción de la tensión superficial (STred) como resultado de la producción de biosurfactante a diferentes temperaturas, con y sin control del pH.

		30°C		37°C		40°C
	Time (h)	Biomass(g/L)	STred	Biomass(g/L)	STred	Biomass(g/L)	STred
Without pH control	0	0.1 ± 0.0^a	–	0.1 ± 0.0^a	–	0.1 ± 0.0^a	–
	6	4.6 ± 0.1^f	16.4 ± 0.5^a	4.8 ± 0.0^f	22.5 ± 0.5^cdef	2.3 ± 0.1^b	18.1 ± 0.5^ab
	16	5.3 ± 0.1^g	21.9 ± 0.2^cde	5.4 ± 0.2^gh	24.4 ± 2.5^fgh	3.3 ± 0.0^c	19.7 ± 1.7^bc
	24	5.7 ± 0.2^hi	22.8 ± 1.0^cdef	5.4 ± 0.0^g	24.7 ± 2.0^fgh	3.6 ± 0.1^d	22.1 ± 0.7^cde
With pH control	0	0.1 ± 0.0^a	–	0.1 ± 0.0^a	–	0.1 ± 0.0^a	–
	6	5.4 ± 0.0^g	21.1 ± 1.2^cd	6.0 ± 0.1^i	20.0 ± 0.5^bc	4.6 ± 0.1^f	23.3 ± 1.0^defg
	16	6.8 ± 0.0^k	21.4 ± 3.5^defgh	7.1 ± 0.1^l	23.7 ± 1.4^defgh	4.0 ± 0.1^e	22.8 ± 0.9^cdef
	24	6.5 ± 0.1^j	24.2 ± 1.3^efgh	6.4 ± 0.1^j	26.4 ± 1.6^h	3.9 ± 0.1^e	25.7 ± 1.2^gh

*Mean values (n = 3) ± standard deviation. Different letters show statistically significant difference among the values in the table (P < 0.05).

Intracellular biosurfactant and/or biosurfactant adsorbed onto cell membrane was extracted with PBS (pH 7.0).

*Valores medios (n = 3) ± desviación estándar. Diferentes letras muestran diferencias estadísticamente significativas entre los valores de la tabla (P < 0,05).

El biosurfactante intracelular y/o adsorbido sobre la membrana celular se extrajo con PBS (pH 7,0).