The mutation induced by space conditions in Escherichia coli

Table 1 Properties of the boarded E. coli strains

Strain	Genotype
A2	Ara (lac proB)strA/F’lacI-proA+B+
A3	Ara (lac proB)strA/F’lacIqpro+
CSH108	Ara (gpt-lac)gyrA argEamproB/F’lacI-Z-proA+B+

Table 2 The Arg⁺ reversion frequency of strain CSH108 in different boarding ways

Sample	Group	Arg+ reversion frequency (× 10-8)
Boarding sample	Group I	2.9
	Group II	1.8
	Group III	26.3
Ground control	A(1)	1.2
	B(2)	2.8

(1) Ground control: Strain was kept at room temperature; (2) Ground control: Strain was stored in freezer (-60 °C).

Table 3 The occurrence of Lac⁺ phenotype among Arg⁺ revertants

Sample	Group	Total No. of Arg+ reversion	No. of Lac+	Lac+/Arg+ (%)
Boarding sample	Group I	60	25	41.7
	Group II	139	52	37.4
	Group III	384	376	97.9
Ground control	A(1)	36	14	38.9
	B(2)	39	27	69.2

A⁽¹⁾ and B⁽²⁾ are the same with that in Table 2.

Table 4 The survival and frequency of LacI^- mutant from A3 strain

Sample	Group	Survival (× 108)	LacI- frequency (× 10-8)
Boarding sample	Group I	3.6	0.4
	Group II	5.5	240.0
	Group III	3.0	15.8
Ground control	A(1)		3.6

All figures were means of four tests. (1) Ground control: strain was kept at room temperature.