Fatty acid profiles and desaturase-encoding genes are different in thermo- and psychrotolerant strains of the Bacillus cereus Group

Table 1 Distribution of key fatty acids (FA), desA and desB according to phylogenetic group in B. cereus sl

Categories to which the tested strains and the tested genomes belong			FA%										FA profile category based on i13/i15 ratio	% of genomes positive for Δ5 and Δ10 desaturases (TblastN)
Phylo-genetic group	Growth range (T, °C)	Major thermotype	Saturated FA (SFA)			Unsaturated FA (UFA)								desA (Δ5)	desB (Δ10)
Phylo-genetic group	Growth range (T, °C)	Major thermotype	i13	i15	n16	i16:1 (5)*	C16:1 (5)*	i17:1 (5)*	i16:1 (10)^#	C16:1 (10)^#	i17:1 (10)^#	a17:1 (10)^#		desA (Δ5)	desB (Δ10)
VII	20–52	T	5.58 ± 1.17	37.95 ± 1.64	11.28 ± 2.14	0.05 ± 0.05	0.02 ± 0.01	0.08 ± 0.03	1.01 ± 0.43	4.09 ± 0.98	1.06 ± 0.47	0.72 ± 0.30	4	0	100
I	10–43	M	11.98 ± 0.49	13.11 ± 0.16	8.69 ± 0.24	0.07 ± 0.05	0.05 ± 0.01	0.13 ± 0.02	3.08 ± 0.17	13.14 ± 0.77	2.54 ± 0.19	1.16 ± 0.08	2	0	100
III	15–45	HM	16.33 ± 0.92	25.69 ± 0.78	7.53 ± 3.23	0.45 ± 0.09	0.31 ± 0.02	6.28 ± 3.18	1.93 ± 0.82	5.76 ± 0.6	3.27 ± 1.55	0.60 ± 0.39	3	99	100
IV	10–45	M	18.66 ± 1.44	20.86 ± 0.59	12.47 ± 0.15	0.26 ± 0.05	0.50 ± 0.03	3.21 ± 0.49	0.81 ± 0.14	6.25 ± 0.34	1.29 ± 0.23	0.54 ± 0.05	2	96	100
V	9–40	IM	18.71 ± 1.34	17.01 ± 1.92	14.55 ± 1.96	0.42 ± 0.13	0.66 ± 0.06	3.93 ± 1.05	0.69 ± 0.22	4.31 ± 1.13	0.79 ± 0.27	0.41 ± 0.13	2	100	100
II	7–40	LP	17.00 ± 1.51	18.94 ± 2.36	14.75 ± 1.55	0.53 ± 0.13	1.24 ± 0.05	5.26 ± 0.5	0.54 ± 0.13	3.50 ± 0.65	0.70 ± 0.09	0.21 ± 0.09	2	100	100
VI	5–37	HP	20.15 ± 3.3	12.02 ± 0.94	14.67 ± 3.23	0.53 ± 0.31	1.09 ± 0.13	8.05 ± 5.34	0.57 ± 0.4	4.99 ± 1.22	1.02 ± 0.61	0.46 ± 0.16	1	100	100

Phylogenetic groups and growth temperature ranges are described in previous works [15, 21].
FA proportions obtained from the FAMEs extractions and GC–MS analysis for a total of 21 representative strains are presented as mean value ± standard deviation (sd) (n = 2–6 representative strains, with 1–3 replicates). FA nomenclature is: iX: iso-FA with X carbons; aX: anteiso-FA with X carbons; nX: saturated FA with X carbons. For unsaturated FA, symbol “:” is prefixed to the number of unsaturations in FA chain; position of unsaturation in FA chain is indicated between parentheses. The symbol “*” indicates that the FA is unsaturated by DesA and “#” indicates that the FA is unsaturated by DesB.
TblastN search was performed to find orthologs of D5 desaturase gene (desA) and D10 desaturase gene (desB) (locus BC_2983 and BC_0400 respectively in strain ATCC 14579T) among 210 B. cereus sl genomes representative of the seven major phylogenetic groups. For both the in silico search of desA and desB orthologs, the number of tested genomes (found in databanks in September of 2014) was 3 for group VII, 74 for group III, 70 for group VI, 7 for group I, 18 for group V, 8 for group II, 30 for group VI.
Thermotypes: T thermotolerant, HM highly mesophilic, M mesophilic, LP low psychrotolerant, HP highly psychrotolerant.

ISSN: 1756-0500