. 2020 Sep 2;13:153. doi: 10.1186/s13068-020-01792-y

Table 1.

Archaeal heterotrophic hyperthermophiles and characterized GHs

Species*	Growth range [°C]	T_opt [°C]	Characterized GH derived from organism**	T_opt [°C]	T_stab	Genbank accession no.***
Pyrococcus furiosus [25]	70–103	100	Endoglucanase (GH12) extracellular enzyme [46] No Genbank	100	T_1/2 40 h at 95 °C	WP_011011985.1 (from CAZy website)
			Endoglucanase (GH16) extracellular enzyme [47]	105	100% of residual activity after incubation at 80 °C for 110 h	AF013169
			Amylase extracellular enzyme [44]	100	> 60% relative activity at 120 °C after incubation for 1 h	n.l.
			Amylase intra- and extracellular enzymes [43]	106	30% residual activity after incubation for 8 h at 98 °C	n.l.
			Amylase extracellular enzyme [48]	100	80% residual activity after incubation for 6 h at 100 °C	U96622
			Amylase intracellular enzyme [49]	100	> 80% residual activity after incubation for 2 h at 100 °C	n.l.
			Glucosidase intracellular enzyme [50]	102–105	T_1/2 85 h at 100 °C	n.l.
			Glucosidase secretion n.l. [51]	100	80% residual activity after incubation for 1 h at 100 °C	AF013169
Pyrococcus horikoshii [26]	< 80–102	98	Endoglucanase (GH5) extracellular enzyme [52]	97	Relative activity 80% after incubation at 97 °C for 3 h	AAQ31833.1 (from CAZy website)
Pyrococcus woesei [53]	n.l.	100–103	Amylase extracellular enzyme [54]	100	No loss of activity after incubation at 90 °C for 6 h	n.l.
Palaeococcus pacificus [55]	50–90	80	Cyclodextrinase PpCD (GH13) secretion n.l. [56]	95	> 90% relative activity after 8 h at 85 °C	WP_048164969
Thermofilum pendens [57]	85–90	Up to 95	Glucosidase (GH 3) intracellular enzyme [51]	90	50% residual activity after incubation for 60 min at 95 °C	YP_920894
Staphylothermus marinus [58]	n.l.	98	Amylase SMMA (GH13) secretion n.l. [59]	100	Melting point T_m 109 °C	WP_011838911.1
Thermococcus chitonophagus [60]	60–93	85	Chitinase chi70 associated with outer cell membrane [61]	70	> 50% activity after incubation at 120 °C for 1 h	n.l.
Thermococcus kodakarensis [62]	60–100	85	Pullulanase TK-PUL (GH13) secretion n.l. [63]	95–100	T_1/2 45 min at 100 °C	BAD85166.1
Saccharolobus shibatae [64]	Up to 86	81	Endoglucanase (GH 12) secretion n.l. [65]	100	100% activity after incubation at 85 °C for 1 h	LT221867
Sulfolobus acidocaldarius [66]	55–80	70–77	Amylase (GH 57) membrane-bound enzyme [67]	105	T_1/2 2.5 h at 100 °C	AAY80509.1 (from CAZy website)
Saccharolobus solfataricus [68]	n.l.	70	Xylanase membrane-bound enzyme [69]	90	T_1/2 47 min at 100 °C	n.l.
			Endoglucanase SSO1949 (GH 12) extracellular enzyme [41]	80	T_1/2 8 h at 80 °C (pH 1.8)	AAK42142.1; NP_343352.1 (from CAZy website)
			Galactosidase intracellular enzyme [70]	95	> 3 h at 75 °C	n.l.
			Galactosidase secretion n.l. [71]	90	> 2 h at 75 °C	n.I.
			Galactosidase (GH36) intracellular enzyme [72]	90	T_1/2 30 min at 90 °C	n.l.
			Xylosidase (GH 31) secretion n.l. [73]	90	T_1/2 38 h at 90 °C	AJ251975
			Mannosidase (GH 38) intracellular enzyme [74]	85	> 20% activity after 10 min at 80 °C	AAK43108.1; AIX48014.1; CAC24028.1; NP_344318.1 (from CAZy website)
Caldivirga maquilingensis [75]	60–92	85	Galactosidase (GH1) secretion n.l. [76]	110	100% relative activity after 120 min at 90 °C	ABW01253.1
Pyrobaculum aerophilum [77]	75–104	100	Glucosidase (GH31) intracellular [78]	90	46% relative activity after 1 h at 110 °C	gi:18160499
Picrophilus torridus [79]	45–65	60	Glucosidase (GH31) intracellular enzyme [80]	87	81% relative activity after 120 min at 80 °C	AAT42677.1 (from CAZy website)
Picrophilus torridus [79]	45–65	60	Mannosidase (GH38) intracellular enzyme [80]	70	50% relative activity after 1 h at 80 °C (with Cd²⁺⁾	AAT42676.1

Functional screening of metagenomes derived from hydrothermal systems
Metagenome	Characterized GH derived from metagenome (archaeal origin)	T_opt [°C]	T_stab	Genbank accession no.***
Deep sea hydrothermal vent	Endoglucanase (GH 12) extracellular enzyme [81]	92	> 80% activity after incubation at 80 °C for 4,5 h	LN850140 (fosmid insert)
Hot spring	Glucosidase (GH 1) secretion n.l. [40]	90	> 67% activity after incubation at 90 °C for 1.5 h	HG326254

Combinatorial approach of enrichment culture and screening
Enrichment culture*	Archaeon	Characterized GH derived from enrichment culture	T_opt [°C]	T_stab	Genbank accession no.***
Shallow marine vent sample from Vulcano Island, incubation 90 °C, cellulosic substrate, anoxic [82]	Unknown, not cultivated in pure culture, probably related to Thermococcus	Endoglucanase Vul_Cel5A (GH 5) extracellular enzyme [42]	115	T_1/2 43 min at 100 °C	MH910342
		Glucosidase (GH 1) intracellular enzyme [22]	105	T_1/2 99 min at 75 °C	MN329095
Sample from 94 °C geothermal pool of northern Nevada, incubated at 90 °C, cellulosic substrates, anoxic [83]	Unknown, not cultivated in pure culture, probably related to Ignisphaera	Endoglucanase EBI-244 (multidomain) extracellular enzyme [83]	109	T_1/2 4.5 h at 100 °C	JF509452
In situ enrichment culture in hot vent (76–99 °C, Kuril archipelago) using xylan as carbon source [84]	Thermococcus sp. Strain 2319X1	Multidomain glycosidase MDG (Multidomain) extracellular enzyme Full-length protein Truncated GH5 version [84]	60 90	n.l. n.l.	CP012200 (genome)

Selection criteria of the reported GHs shown in the table are a high thermo-activity and thermo-stability. GH families (in brackets) and Genbank accession numbers are provided if the respective articles contain this information

n.l. not listed in the original paper

* Literature source reports the first description of the organism

** Literature source reports the enzyme characterization

*** As provided by the literature source or CAZy