Xylan-mediated aggregation of Lactobacillus brevis and its relationship with the surface properties and mucin-mediated aggregation of the bacteria

Figures & data

Fig. 1. Aggregation rates of L. brevis strains after the addition of xylan (A) and microscopic analysis of the strains in the presence (a, c) and absence (b, d) of xylan (B). The representative results by L. brevis strains NBRC 3960 (a, b) and NBRC 13109 (c, d) are shown as the results of optical microscopic analysis. As and Ac represent the optical density at 600 nm of the sample with xylan and the control without xylan, respectively. The soluble fraction of xylan was used, and data for 2 h after xylan addition are shown.

Fig. 2. Analysis of the cell surface proteins of L. brevis by SDS-PAGE. The numbers next to the bands denote the proteins subjected to identification.

Table 1. Identification of the cell surface proteins of L. brevis by MALDI-TOF mass spectrometry.

			Identified protein
Band no. in Fig. 2.	Strain	Mr estimated by SDS-PAGE (kDa)	Protein name	Source	Mr	Protein Score	Accession no. in NCBInr
1	NBRC 3345	41	S-layer protein	L. brevis ATCC 8287	48130	1450	gi|548935
1	NBRC 3690	48	Slp M	L. brevis	51430	1550	gi|380042350
1	NBRC 12005	52	LVIS_2085	L. brevis ATCC 367	31136	644	gi|116334645
1′	NBRC 12005	47	LVIS_2085	L. brevis ATCC 367	31136	663	gi|116334645
1	NBRC 12520	52	LVIS_2085	L. brevis ATCC 367	31136	895	gi|116334645
1′	NBRC 12520	47	LVIS_2085	L. brevis ATCC 367	31136	939	gi|116334645
1	NBRC 13109	41	LVIS_2086	L. brevis ATCC 367	16649	346	gi|116334646
1	NBRC 13110	41	LVIS_2086	L. brevis ATCC 367	16649	323	gi|116334646
1	NBRC 107147^T	49	Slp B	L. brevis DSM 20054	50894	2200	gi|25989136
2	NBRC 3345, 3690, 12005, 12520, 13109, 13110	33	LVIS_1982	L. brevis ATCC 367	36918	916–1440	gi|116334544
			Xylanase/chitin deacetylase	L. brevis ATCC 367	36886	791–1210	gi|116334822
2	NBRC 107147^T	39	Slp D	L. brevis DSM 20054	44544	1490	gi|25989140
			LVIS_1974	L. brevis ATCC 367	44555	1480	gi|116334537
3	NBRC 3345, 3690, 12005, 12520, 13109, 13110, 107147^T	26	Phosphoglycerate mutase	L. brevis ATCC 367	29450	1060–1700	gi|116334724

Fig. 3. Effect of LiCl treatment on the xylan-mediated aggregation rate and zeta potential of L. brevis. As and Ac represent the optical density at 600 nm of the sample with xylan and the control without xylan, respectively. The soluble fraction of xylan was used for the aggregation assay, and data for 2 h after xylan addition are shown. ^aThere was one outlier in aggregation rate of L. brevis NBRC 3960, which was treated with 4 M LiCl, and the value was −1.83 ± 0.58.

Fig. 4. Analysis of the remaining S-layer proteins of L. brevis after LiCl treatment. The bands corresponding to proteins labeled “1” in Figure 2 are shown.

Fig. 5. Effect of NaCl concentration on the xylan-mediated aggregation rate of both of intact and LiCl-treated L. brevis. As and Ac represent the optical density at 600 nm of the sample with xylan and the control without xylan, respectively. The soluble fraction of xylan was used for the aggregation assay, and data for 1 h after xylan addition are shown. ^aStandard assay condition contained 154 mM NaCl which came from saline solution. ^bThe concentration of LiCl treatment was 6 M for L. brevis NBRC 3960 and NBRC 107147^T and 3 M for the other strains, respectively.

Fig. 6. Time course of the aggregation rate of L. brevis after xylan and mucin addition. As and Ac represent the optical density at 600 nm of the sample with xylan or mucin and the control without them, respectively. The soluble fractions of xylan and mucin were used.