Isolation, characterization and localization of extracellular polymeric substances from the cyanobacterium Arthrospira platensis strain MMG-9

Figures & data

Table 1. Fluorescent dyes and conditions.

Name of dye	Buffer used	Incubation time	Excitation λ	Emission λ
DTAF (1 mM)	Carbonate buffer, pH 9.0	Overnight	493 nm	517 nm
Con A-FITC (1 mM)	Phosphate buffer saline, pH 8	20 min	494 nm	518 nm
Lotus-FITC (1 mM)	Phosphate buffer, pH 8	20 min	494 nm	518 nm
CSA-TRITC (1 mM)	Phosphate buffer, pH 8	20 min	540 nm	605 nm
AAA-Alexa 488	Sodium bicarbonate buffer, pH 8.5	20 min	488 nm	518 nm

Table 2. Biochemical characteristics of EPS fractions.

	Total EPS (mg g chl a^−1) *	Carbohydrates (mg g^−1) of dry EPS*	Protein (mg g^−1) of dry EPS*	Uronic acid (mg g^−1) of dry EPS*	Glycosaminoglycan (mg g^−1) of dry EPS*
REPS	201.6 ± 0.15(b)	502.1 ± 0.51(a)	16.2 ± 1.26(b)	15.2 ± 1.5(b)	8.2 ± 1.75(b)
LEPS	84 ± 0. 13(a)	574 ± 0.22(b)	11.1 ± 2.23(a)	6.3 ± 1.31(a)	5.5 ± 0.89(a)
TEPS	275.4 ± 0.14(c)	605.4 ± 0.54(c)	23.3 ± 1.12(c)	21.8 ± 2.81(c)	16.3 ± 1.78(c)
Relative percentages of each component
	Total EPS	Carbohydrates	Protein	Uronic acid	Glycosaminoglycan
REPS	36	30	32	35	27
LEPS	15	34	22	15	18
TEPS	49	36	46	50	55

* Mean ± SE (N = 3). Different letters indicate significant differences, Duncan’s multiple range test (P = 0.05).

Table 3. Comparison of constituent monosaccharidic residues in different EPS fractions of A. platensis MMG-9.

Monomer	REPS		LEPS		TEPS
	* µg mg (Chl a)^−1	Relative %	* µg mg (Chl a)^−1	Relative %	* µg mg (Chl a)^−1	Relative %
Fructose	0 ± 0.0 (a)	0	0 ± 0.0 (a)	0	0 ± 0.0 (a)	0
Fucose	37.9 ± 0.5 (c)	15	22.4 ± 0.6 (b)	9	99.2 ± 1.3 (i)	11
Galactose	47.1 ± 0.4 (d)	19	75.3 ± 3.02 (d)	32	237.8 ± 3.8 (m)	26
Glucose	42.2 ± 1.4 (c)	17	39.1 ± 2.2 (c)	17	198.4 ± 6.5 (k)	22
Mannose	0 ± 0.0 (a)	0	0 ± 0.0 (a)	0	30.7 ± 1.2 (d)	3
Rhamnose	102.3 ± 1.0 (e)	41	79.8 ± 1.7 (d)	34	114.7 ± 1.8 (j)	13
Ribose	0 ± 0.0 (a)	0	0 ± 0.0 (a)	0	15.2 ± 0.8 (b)	2
Xylose	18.3 ± 0.8 (b)	8	19.9 ± 1.3 (b)	8	205.0 ± 8.9 (l)	23

* Mean ± SE (N = 3). Different letters indicate significant differences, Duncan’s multiple range test (P = 0.05).

Figs 1–9. Localization of EPS from A. platensis MMG-9 using confocal laser scanning microscopy. Figs 1, 3. Overlaid images of autofluorescence and stained EPS with DTAF. Figs 2, 4. Spiral trichomes embedded in EPS stained with DTAF. Figs 5–6. Overlaid images of autofluorescence and stained EPS with CSA-TRITC. Fig. 7. Image of EPS stained with CSA-TRITC. Fig. 8. Staining with Con-A-FITC. Fig. 9. Staining with Alexa Fluor 488. Scale bars = 10 µm (Figs 1, 2), 15 µm (Figs 3, 4), 5 µm (Fig. 5), 10 µm (Figs 6–9). Red = cyanobacterial autofluorescence, green = EPS.

Figs 10–14. Localization of EPS from A. platensis MMG-9 using confocal laser scanning microscopy. Figs 10–12. Spiral filaments embedded in EPS stained with Lotus-FITC. Fig. 13. EPS clouds from A. platensis MMG-9 using confocal laser scanning microscopy and three dyes (Lotus-FITC, CSA-TRITC and Alexa Fluor 488). Fig. 14. z-stacks showing the depth of the image (numbers show depth in µm). Scale bars = 15 µm (Fig. 10), 10 µm (Fig. 11), 50 µm (Fig. 12), 10 µm (Fig. 13). Red = cyanobacterial autofluorescence, green = EPS.