Chemosystematic evaluation of the genus Scytonema (Cyanobacteria) based on occurrence of phycobiliproteins, scytonemin, carotenoids and mycosporine-like amino acid compounds

Figures & data

Table 1. Origins of the cyanobacterial isolates investigated and their possible assignment as botanical species on the basis of morphology, morphometry and ecology.

Culture Collection^1	Strain	Code	Assignment	Cell width (µm)	Filament width (µm)	Cell form	Cytoplasm colour	Terminal meristematic zone	Habitat	Locality
ULG	219/6	L1	Scytonema sp1	6.51 ± 0.4	7.9 ± 0.32	disc-shaped	blue-green	slight	aerophytic	on mosses on the rocks in Luxembourg
ULG	223	L2	Scytonema sp2	5.95 ± 0.22	6.81 ± 0.24	disc-shaped	blue-green	slight	aerophytic	on mosses on the rocks in Luxembourg
ULG	363/2	L3	Scytonema sp3	6.3 ± 0.31	7.52 ± 0.31	disc-shaped	blue-green	slight	edaphic	on soil in Luxembourg
ULG	484	F1	Scytonema sp4	7.92 ± 0.29	10.04 ± 0.16	elongate	blue-green	marked	cavernicolous	in a cave in Florida
ULG	490	F2	Scytonema sp5	10.92 ± 0.17	14.03 ± 0.14	disc-shaped	blue-green	slight	atmophytic	in a greenhouse in Florida
ULG	495	F3	Scytonema sp6	6.26 ± 0.12	7.66 ± 0.23	elongate	blue-green	marked	atmophytic	in a greenhouse in Florida
PCC	7110	B1	Scytonema sp7	6.17 ± 0.5	7.66 ± 0.38	elongate	blue-green	marked	atmophytic	Bermuda
ULG	2040	GR1	Scytonema sp8	7.53 ± 0.41	9.73 ± 0.19	elongate	blue-green	marked	edaphic	on soil in Greece
ULG	2041	GR2	Scytonema sp9	10.37 ± 0.15	13.01 ± 0.28	elongate	blue-green	marked	epilithic	on rocks in Greece
ULG	97-7	P1	Scytonema sp10	9.31 ± 0.15	10.77 ± 0.44	disc-shaped	blue-green	slight	corticolous	on the bark of trees in Portugal
ULG	87-602	GE1	Scytonema sp11	5.94 ± 0.34	8.16 ± 0.26	elongate	blue-green	marked	atmophytic	in a greenhouse in Germany
ULG	SA3	GU1	Scytonema sp12	10.41 ± 0.29	12.55 ± 0.5	elongate	violet	marked	atmophytic	Guiana
ULG	87-06	TH1	Scytonema sp13	7.08 ± 0.16	11.13 ± 0.24	elongate	violet	marked	atmophytic	Thailand
ULG	87-18	TH2	Scytonema sp14	9.8 ± 0.42	12.53 ± 0.15	elongate	violet	marked	corticolous	on the bark of trees in Thailand
ULG	Th 95-1	TH3	Scytonema sp15	12.75 ± 0.36	15.94 ± 0.23	disc-shaped	blue-green	slight	atmophytic	Thailand
ULG	Th 95-2	TH4	Scytonema sp16	10.95 ± 0.29	13.58 ± 0.13	elongate	blue-green	slight	epilithic	on rocks in Thailand
ULG	Th 95-23	TH5	Scytonema sp17	10.32 ± 0.43	13.51 ± 0.44	elongate	violet	marked	atmophytic	Thailand
ULG	Aus 95-20/2	A1	Scytonema sp18	8.51 ± 0.17	12.88 ± 0.25	elongate	violet	marked	edaphic	on sand in Australia
ULG	179/c	SW1	Scytonema sp19	14.63 ± 0.46	26.73 ± 0.28	disc-shaped	blue-green	slight	atmophytic	Switzerland
ULG	87-601	SI1	Scytonema sp20	8.11 ± 0.39	10.46 ± 0.17	elongate	blue-green	slight	atmophytic	Singapore
ULG	87-595/1	SI2	Scytonema sp21	9.78 ± 0.13	11.78 ± 0.34	elongate	violet	marked	edaphic	on soil in Singapore
ULG	750	NG1	Scytonema sp22	11.20 ± 0.25	12.98 ± 0.45	elongate	violet	marked	corticolous	on the bark of trees in Papua New Guinea
ULG	780	NG2	Scytonema sp23	15.4 ± 0.29	19.03 ± 0.28	elongate	violet	marked	corticolous	on the bark of trees in Papua New Guinea
ULG	871/1	NG3	Scytonema sp24	8.23 ± 0.21	9.68 ± 0.37	elongate	violet	marked	epizoic	on dead coral in Papua New Guinea
ULG	871/4	NG4	Scytonema sp25	15.4 ± 0.43	19.03 ± 0.29	elongate	violet	marked	atmophytic	Papua New Guinea
ULG	873/1	NG5	Scytonema sp26	13.5 ± 0.5	19.0 ± 0.18	disc-shaped	blue-green	slight	corticolous	on the bark of trees in Papua New Guinea
ULG	873/2	NG6	Scytonema sp27	15.4 ± 0.14	19.03 ± 0.26	elongate	violet	marked	corticolous	on the bark of trees in Papua New Guinea
ULG	1037	NG7	Scytonema sp28	15.0 ± 0.24	19.27 ± 0.46	disc-shaped	blue-green	slight	corticolous	on the bark of trees in Papua New Guinea
ULG	1100	NG8	Scytonema sp29	5.57 ± 0.25	7.99 ± 0.26	elongate	blue-green	slight	epilithic	on rocks in Papua New Guinea
ULG	1152	NG9	Scytonema sp30	4.15 ± 0.43	5.95 ± 0.43	elongate	blue-green	slight	epilithic	on walls in Papua New Guinea
ULG	1570	NG10	Scytonema sp31	11.59 ± 0.27	15.52 ± 0.17	elongate	violet	marked	epilithic	on rocks in Papua New Guinea
ULG	1908	NG11	Scytonema sp32	15.4 ± 0.41	19.03 ± 0.25	elongate	violet	marked	atmophytic	Papua New Guinea
ULG	87-83	NG12	Scytonema sp33	7.38 ± 0.5	9.21 ± 0.32	elongate	blue-green	slight	epilithic	on rocks and soil in Papua New Guinea
ULG	87-122	NG13	Scytonema sp34	9.48 ± 0.29	10.93 ± 0.43	elongate	blue-green	slight	atmophytic	Papua New Guinea
ULG	97-78	N1	Scytonema stuposum	12.4 ± 0.17	20.74 ± 0.21	disc-shaped	blue-green	slight	atmophytic	Nepal
ULG	97-106b	SW2	Scytonema myochrous	19.46 ± 0.27	26.94 ± 0.12	disc-shaped	blue-green	slight	atmophytic	Switzerland
ULG	97-63a	N2	Scytonema sp35	11.94 ± 0.21	14.3 ± 0.42	elongate	violet	marked	atmophytic	Nepal
ULG	KAN2	N3	Scytonema sp36	5.51 ± 0.19	7.08 ± 0.17	elongate	blue-green	slight	atmophytic	Nepal
ULG	VAPOR	SP1	Scytonema julianum	7.44 ± 0.42	8.39 ± 0.46	elongate	blue-green	marked	cavernicolous	in a cave in Spain
ULG	96-12	GE2	Scytonema sp37	11.20 ± 8	14.75 ± 0.39	elongate	violet	marked	atmophytic	Germany

¹ ULG: University of Liège; PCC: Pasteur Culture Collection.

Fig. 1. Percentages of total phycobiliproteins in different Scytonema cultures. Scytonema isolate codes are given in Table 1.

Fig. 2. Cluster analysis of Scytonema isolates according to their pigment characteristics. Scytonema isolate codes are given in Table 1.

Table 2. Characteristics of the three groups of Scytonema distinguished by cluster analysis of biochemical data (Fig. 2).

Group	Isolates	Carotenoids	MAAs	Phycobiliproteins	Scytonemin
1	L1, L2, L3, F2, P1, TH3, TH4, SW1, SI1, NG5, NG7, NG8, NG9, NG12, NG13, SW2, N3, N1	β-carotene, canthaxanthin, echinenone, zeaxanthin	absent	allophycocyanin, phycocyanin	present
2	GU1, TH1, TH2, TH5, A1, SI2, NG1, NG2, NG3, NG4, NG6, NG10, NG11, N2, GE2	β-carotene, canthaxanthin, echinenone, isozeaxanthin, myxoxanthophyll	present	allophycocyanin, phycocyanin, phycoerythrin	present
3	F1, F3, B1, GR1, GR2, GE1, SP1	β-carotene, canthaxanthin, echinenone	present (only shinorine)	allophycocyanin, phycocyanin, phycoerythrocyanin	absent

Table 3. Comparison of the phycobiliproteins, scytonemin, carotenoids and mycosporine-like amino acid data (mean ± S.D.), evaluated by non-parametric Kruskal–Wallis tests (P < 0.05) among the three groups of Scytonema cultures distinguished by cluster analysis (Fig. 2).

	Group 1 (N = 18)	Group 2 (N = 15)	Group 3 (N = 7)	Statistic value (H)	P^1
Carotenoids (carotenoid : chlorophyll a by molecular weight)
β-carotene	9.50 ± 13.01	24.91 ± 43.92	12.82 ± 14.66	0.703	0.704^ns
canthaxanthin	8.08 ± 8.96	16.14 ± 32.69	10.02 ± 16.16	0.024	0.988^ns
echinenone	5.63 ± 5.37	9.59 ± 14.14	9.87 ± 12.72	0.589	0.745^ns
isozeaxanthin	0	28.37 ± 48.65	0	36.290	0.000***
myxoxanthophyll	0	13.13 ± 25.83	0	36.290	0.000***
zeaxanthin	5.26 ± 5.45	0	0	34.749	0.000***
MAAs (A335 × mg^−1 chl a)
1	0.03 ± 0.11	0.35 ± 0.76	0	3.000	0.223^ns
2 (shinorine)	0	0	1.32 ± 0.94	38.533	0.000***
3	0	0.08 ± 0.32	0	1.667	0.435^ns
4	0	0.01 ± 0.04	0	1.667	0.435^ns
5	0.01 ± 0.02	0	0	1.222	0.543^ns
6 (stanierine)	0	0.15 ± 0.58	0	1.667	0.435^ns
7	0.01 ± 0.04	0	0	1.222	0.543^ns
8 (asterina-330)	0.02 ± 0.08	0.96 ± 1.25	0	33.109	0.000***
9	0	0.01 ± 0.03	0	1.667	0.435^ns
10	0	0.05 ± 0.21	0	1.667	0.435^ns
11	0	0.03 ± 012	0	1.667	0.435^ns
12	0	0.11 ± 0.44	0	1.667	0.435^ns
13	0	0.18 ± 0.36	0	7.197	0.027*
14	0	0.09 ± 0.36	0	1.667	0.435^ns
Phycobiliproteins (mg PB × mg^–1 chl a)
allophycocyanin	3.14 ± 0.85	3.63 ± 0.58	4.42 ± 0.74	11.771	0.003**
phycocyanin	4.38 ± 0.75	4.81 ± 057	5.55 ± 0.72	9.752	0.008**
phycoerythrin	0	6.68 ± 0.72	0	36.290	0.000***
phycoerythrocyanin	0	0	8.22 ± 1.10	38.533	0.000***
Scytonemin (A370 × mg^–1 chl a)
scytonemin	0.68 ± 1.08	1.43 ± 1.65	0	20.690	0.000***

¹ Kruskal–Wallis test. *P < 0.05; **P < 0.01, *** P < 0.001, ns (not significant).

Table 4. Mycosporine-like amino acid compounds and scytonemin in different isolates of Scytonema. The numbers represent the order of leaving the HPLC column. The specific MAA contents are expressed as absorbance (at 335 nm) mg⁻¹ chl a. The specific scytonemin contents are expressed as absorbance (at 370 nm) mg⁻¹ chl a. – = not detected. For Scytonema isolate codes, see Table 1.

Isolate	1	2 (shinorine)	3	4	5	6 (stanierine)	7	8 (asterina-330)	9	10	11	12	13	14	scytonemin
L1	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.22
L2	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.1
L3	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.13
F1	–	0.27	–	–	–	–	–	–	–	–	–	–	–	–	–
F2	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.15
F3	–	2.21	–	–	–	–	–	–	–	–	–	–	–	–	–
B1	–	1.51	–	–	–	–	–	–	–	–	–	–	–	–	–
GR1	–	1.65	–	–	–	–	–	–	–	–	–	–	–	–	–
GR2	–	0.11	–	–	–	–	–	–	–	–	–	–	–	–	–
P1	–	–	–	–	–	–	–	–	–	–	–	–	–	–	4.45
GE1	–	0.93	–	–	–	–	–	–	–	–	–	–	–	–	–
GU1	–	–	–	–	–	–	–	0.75	–	–	–	–	–	–	0.23
TH1	–	–	–	0.15	–	–	–	0.1	0.13	–	–	–	–	–	6.69
TH2	–	–	1.23	–	–	–	–	0.1	–	–	–	–	–	–	1.52
TH3	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.19
TH4	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.12
TH5	–	–	–	–	–	–	–	0.13	–	–	–	–	1.21	–	1.59
A1	–	–	–	–	–	–	–	1.4	–	–	–	–	–	–	1.75
SW1	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.12
SI1	–	–	–	–	–	–	–	–	–	–	–	–	–	–	1.1
SI2	–	–	–	–	–	–	–	0.52	–	–	–	–	0.65	–	2.24
NG1	–	–	–	–	–	2.23	–	0.45	–	0.8	–	1.7	0.23	1.4	1.73
NG2	2.42	–	–	–	–	–	–	0.35	–	–	–	–	–	–	2.21
NG3	1.32	–	–	–	–	–	–	0.51	–	–	–	–	–	–	1.24
NG4	1.5	–	–	–	–	–	–	2.58	–	–	–	–	–	–	0.25
NG5	–	–	–	–	–	–	–	–	–	–	–	–	–	–	1.5
NG6	–	–	–	–	–	–	–	4.52	–	–	–	–	–	–	1.4
NG7	–	–	–	–	–	–	–	–	–	–	–	–	–	–	1.44
NG8	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.23
NG9	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.18
NG10	–	–	–	–	–	–	–	0.13	–	–	0.47	–	–	–	0.2
NG11	–	–	–	–	–	–	–	0.16	–	–	–	–	0.56	–	0.11
NG12	–	–	–	–	–	–	–	–	–	–	–	–	–	–	1.55
NG13	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.11
N1	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.19
SW2	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.32
N2	0.45	–	–	–	0.1	–	0.15	0.42	–	–	–	–	–	–	0.12
N3	–	–	–	–	–	–	–	–	–	–	–	–	–	–	0.1
SP1	–	2.59	–	–	–	–	–	–	–	–	–	–	–	–	–
GE2	–	–	–	–	–	–	–	2.21	–	–	–	–	–	–	0.27

Fig. 3. Percentages of total carotenoids in different Scytonema cultures. Scytonema isolate codes are given in Table 1.

Table 5. Comparison of the phycobiliproteins, scytonemin, carotenoids and mycosporine-like amino acid data among the different habitat groups of Scytonema, evaluated by non-parametric Kruskal–Wallis tests (P < 0.05). The habitats represented among the 40 isolates were aerophytic (2), epilithic (7), cavernicolous (2), atmophytic (18), edaphic (4), and corticolous (7).

	Statistic value (H)	P^1
Carotenoids
β-carotene	0.199	0.999^ns
Canthaxanthin	0.989	0.963^ns
Echinenone	0.654	0.985^ns
Isozeaxanthin	3.592	0.609 ^ns
Myxoxanthophyll	3.480	0.623 ^ns
Zeaxanthin	4.375	0.497 ^ns
MAAs
1	1.211	0.944^ns
2 (shinorine)	11.823	0.037*
3	4.714	0.452^ns
4	1.222	0.943^ns
5	1.222	0.943^ns
6 (stanierine)	4.714	0.452^ns
7	1.222	0.943^ns
8 (asterina-330)	4.245	0.515 ^ns
9	1.222	0.943^ns
10	4.714	0.452^ns
11	4.714	0.452^ns
12	4.714	0.452^ns
13	2.357	0.798^ns
14	4.714	0.452^ns
Phycobiliproteins
Allophycocyanin	5.723	0.334 ^ns
Phycocyanin	8.007	0.156 ^ns
Phycoerythrin	2.936	0.710 ^ns
Phycoerythrocyanin	11.745	0.038*
Scytonemin
Scytonemin	14.202	0.014*

¹ Kruskal–Wallis test. *P < 0.05, ns (not significant).

Fig. 4. Principal component analysis (PCA) (with standardization) of 40 Scytonema cultures (open triangles included in group 1; open circles in group 2 and open squares in group 3), pigment contents and morphometry. Scytonema isolate codes are given in Table 1 and MAAs codes in Table 4.