Comparison of two methods for root nodule bacteria preservation: Lyophilization and liquid nitrogen freezing

• Published in: Journal of microbiological methods Vol. 24; no. 3; pp. 231 - 237
• Main Authors: Safronova, V.I., Novikova, N.I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1996
• Subjects: Bradyrhizobium; Freezing in liquid nitrogen; Induction of prophage; Lyophilization; Rhizobium; Root nodule bacteria; Survival of bacteria; Symbiotic properties of bacteria; Symbiotic properties of bacteria; Induction of prophage; Lyophilization; Freezing in liquid nitrogen; Root nodule bacteria; Survival of bacteria
• ISSN: 0167-7012; 1872-8359
• DOI: 10.1016/0167-7012(95)00042-9

Liquid nitrogen freezing and freeze-drying were compared as methods for long-term preservation of root nodule bacteria. The viability of cells and the maintenance of symbiotic properties were checked in the following strains:
Rhizobium meliloti 1723;
R. leguminosarum bv.
trifolii 1326;
R. leguminosarum bv.
viciae 1026;
R. leguminosarum bv.
phaseoli 2620;
R. galegae 0702, 0716, 0720;
Bradyrhizobium japonicum 2490 and
B. sp.
Lupinus 1614 which possess high and low growth rates. The level of prophage induction before and after preservation was estimated in five lysogenic strains:
R. galegae 0703(07-2),
0703(
1
OW
)
;
R. loti 1801(18-5), 1801(18-6) and
R. meliloti D1(H19). In contrast to freeze-drying the liquid nitrogen freezing, for the most part, was not accompanied with a significant drop in the suspension titre and did not change the symbiotic properties of root nodule bacteria. The level of prophage induction in some lysogenic strains after freezing was considerably lower than that after freeze-drying. The results obtained in this work demonstrated that liquid nitrogen freezing offers significant advantages over lyophilization.