Xylanolytic and Ethanologenic Potential of Gut Associated Yeasts from Different Species of Termites from India

Figures & data

Figure 1. Phylogenetic placement of yeasts under study based on partial LSU-rRNA gene sequences. The tree was reconstructed using the maximum-likelihood analysis of 647 aligned positions with the Tamura–Nei model. The scale bar indicates the number of expected substitutions per site. The numbers provided on branches are frequencies with which a given branch appeared in 1000 bootstrap replications. The tree was rooted with Rhizopus oryzae.

Table 1. Summary of yeasts obtained in this study and their biochemical profile.

Sampling details		No. of isolates obtained	Representative strain		Identification using LSU rRNA gene	Sugar fermentation and assimilation profile
Termite	Location		Strain code	GenBank accession number		Glu	Gal	L-Ara	Mal	Man	Suc	Xyl
Coptotermes heimi	Singalandhapuram, Tamil Nadu (11.420428 °N, 78.220487 °E)	25	TS1	MH890522	Candida tropicalis	++^a	++	––^b	++	+–^c	+–	+–
			TS8	MH900181	Candida tropicalis	++	++	––	++	+–	+–	+–
			TS21	MH900183	Kodamaea ohmeri	++	+–	––	+–	+–	++	+–
			TS25	MH890501	Trichosporon coremiiforme	+–	+–	––	+–	+–	+–	+–
			TS32	MH900185	Candida tropicalis	++	++	––	++	+–	+–	+–
			TS33	MH900182	Trichosporon asahii	+–	––	––	w–^d	+–	––	+–
			TS36	MH900186	Candida tropicalis	++	++	––	++	+–	+–	+–
			TS50	MH900184	Kodamaea ohmeri	++	+–	w–	+–	+–	++	w–
Odontotermes obesus	Pune, Maharashtra (18.520745 °N, 73.8315643 °E)	19	TY6	MH885532	Sugiyamaella smithiae	+–	+–	+–	––	+–	––	+–
			TY9	MH900195	Sugiyamaella valenteae	+–	+–	+–	––	+–	––	+–
			TY45	MH900196	Sugiyamaella valenteae	+–	+–	+–	+–	+–	––	+–
			TYS1	MH890500	Pichia manshurica	+–	––	w–	––	+–	––	+–
Odontotermes javanicus	Pune, Maharashtra (18.520745 °N, 73.8315643 °E)	35	STAG1.1	MN186827	Vishniacozyma taibaiensis	+–	+–	w–	+–	+–	+–	+–
			STAG1.2	MN124445	Papiliotrema flavescens	+–	+–	+–	+–	+–	+–	+–
			STAG1.4	MN186830	Papiliotrema laurentii	+–	+–	+–	+–	+–	+–	+–
			STAG1.7	MN124507	Pseudozyma hubeiensis	+–	+–	+–	+–	+–	+–	+–
			STAG1.8	MN186833	Papiliotrema mangalensis	+–	w–	+–	+–	+–	+–	+–
			STAG1.11	MN186831	Papiliotrema laurentii	+–	+–	+–	+–	+–	+–	+–
			STAG1.12	MN124516	Pseudozyma hubeiensis	+–	+–	+–	+–	+–	+–	+–
			STAG1.13	MN124389	Hannaella luteola	+–	+–	+–	w–	+–	+–	+–
			STAG1.14	MN124394	Hannaella pagnoccae	+–	+–	+–	+–	+–	+–	+–
			STAG1.78	MN186825	Vishniacozyma dimennae	+–	+–	w–	+–	––	+–	+–
			STAG1.88	MN186824	Cystobasidium slooffiae	+–	+–	w–	w–	+–	+–	+–

^a (++): growth and fermentation both positive.

^b (––): no growth and no fermentation.

^c (+–): growth positive but no fermentation.

^d (w–): weakly positive growth but no fermentation.

Table 2. Ethanol and xylanase production profiles of yeasts.

Termite	Strain code	Yeast species	Ethanol^a				Xylanase (IU)^f	Cellulase (IU)^g
			Concentration (g/L)^b	Yield (g/g)^c	Productivity (g/L/h)^d	Efficiency (%)^e
Coptotermes heimi	TS1	Candida tropicalis	3.78 ± 0.01	0.38	0.053	73.97	0.50 ± 0.03	NP
	TS8	Candida tropicalis	4.07 ± 0.00	0.40	0.057	79.64	0.56 ± 0.02
	TS21	Kodamaea ohmeri	3.97 ± 0.02	0.39	0.055	77.69	0.79 ± 0.04
	TS25	Trichosporon coremiiforme	NP	NP	NP	NP	0.22 ± 0.03
	TS32	Candida tropicalis	4.42 ± 0.04	0.44	0.061	86.50	0.22 ± 0.03
	TS33	Trichosporon asahii	NP	NP	NP	NP	0.27 ± 0.01
	TS36	Candida tropicalis	4.31 ± 0.01	0.43	0.060	84.34	0.33 ± 0.01
	TS50	Kodamaea ohmeri	3.02 ± 0.03	0.30	0.042	59.09	0.63 ± 0.03
Odontotermes javanicus	STAG1.1	Vishniacozyma taibaiensis	NP	NP	NP	NP	0.15 ± 0.00	NP
	STAG1.2	Papiliotrema flavescens	NP	NP	NP	NP	NP
	STAG1.4	Papiliotrema laurentii	NP	NP	NP	NP	0.11 ± 0.00
	STAG1.7	Pseudozyma hubeiensis	NP	NP	NP	NP	1.31 ± 0.01
	STAG1.8	Papiliotrema mangalensis	NP	NP	NP	NP	0.89 ± 0.02
	STAG1.11	Papiliotrema laurentii	NP	NP	NP	NP	0.27 ± 0.00
	STAG1.12	Pseudozyma hubeiensis	NP	NP	NP	NP	0.61 ± 0.01
	STAG1.13	Hannaella luteola	NP	NP	NP	NP	NP
	STAG1.14	Hannaella pagnoccae	NP	NP	NP	NP	1.17 ± 0.01
	STAG1.78	Vishniacozyma dimennae	NP	NP	NP	NP	NP
	STAG1.88	Cystobasidium slooffiae	NP	NP	NP	NP	0.30 ± 0.00
Odontotermes obesus	TY6	Sugiyamaella smithiae	0.20 ± 0.01	0.02	0.003	03.91	0.11 ± 0.03	NP
	TY9	Sugiyamaella valenteae	NP	NP	NP	NP	0.20 ± 0.03
	TY45	Sugiyamaella valenteae	NP	NP	NP	NP	0.24 ± 0.02
	TYS1	Pichia manshurica	NP	NP	NP	NP	0.43 ± 0.02

^a Initial glucose concentration is 10 g/L.

^b Ethanol concentration (g/L).

^c Ethanol yield (g/g): ratio between ethanol concentration (g/L) and glucose consumed (g/L).

^d Ethanol productivity (g/L/h): ratio of ethanol concentration (g/L) and fermentation time (72 h).

^e Fermentation efficiency (%): percentage of the maximal theoretical yield of ethanol (0.511 g ethanol/g glucose).

^f Xylanase activities (IU) were obtained from cell-free supernatants induced by xylan for 72 h at 30 °C and assessed at 45 °C.

^g Cellulase activities (IU) were obtained from cell-free supernatants induced by CMC for 72 h at 30 °C and assessed at 45 °C.

NP: not produced.

Figure 2. Effect of temperature, pH, and sugar concentration on ethanol production. (A) Ethanol production (in g/L) by TS32 and standard strain NCIM3186 tested at different temperatures; 20, 25, 30, 35, 37, and 40 °C. (B) Ethanol production (in g/L) at 35°C and different pH tested; 4.0, 4.5, 5.0, 5.5, and 6.0. (C) Ethanol production (in g/L) at 35 °C, pH 4.5 and varying glucose concentrations; 5%, 10%, 15%, 20%, and 30%. Asterisks (*) symbol denotes the level of significance with a p value <0.05 analyzed by one-way ANOVA.

Table 3. Ethanol production from alkali-pretreated rice straw hydrolysate.

Yeast strain	Sugars released (g/L)				Ethanol
	Glucose	Xylose	Arabinose	Total	Concentration (g/L)^a	Yield (g/g)^b	Productivity (g/L/h )^c	Efficiency (%)^d
TS32	20.94	10.60	2.40	33.94	8.95 ± 1.17	0.42	0.12	83.56
NCIM3186					8.65 ± 0.33	0.41	0.12	80.76

^a Ethanol concentration (g/L).

^b Ethanol yield (g/g): ratio between ethanol concentration (g/L) and glucose consumed (g/L).

^c Ethanol productivity (g/L/h): ratio of ethanol concentration (g/L) and fermentation time (72 h).

^d Fermentation efficiency (%): percentage of the maximal theoretical yield of ethanol (0.511 g ethanol/g glucose).