Abstract
Deinococcus radiodurans exhibits growth medium-dependent morphological variation in cell shape, but there is no evidence whether this phenomenon is observed in other members of the Deinococcaceae family. In this study, we isolated a red-pigmented, aerobic, Deinococcus indicus strain DR1 from Dadri wetland, India. This D. indicus strain exhibited cell–morphology transition from rod-shaped cells to multi-cell chains in a growth-medium-dependent fashion. In response to addition of 1% casamino acids in the minimal growth medium, rod-shaped cells formed multi-cell chains. Addition of all 20 amino acids to the minimal medium was able to recapitulate the phenotype. Specifically, a combination of L-methionine, L-lysine, L-aspartate, and L-threonine caused morphological alterations. The transition from rod shape to multi-cell chains is due to delay in daughter cell separation after cell division. Minimal medium supplemented with L-ornithine alone was able to cause cell morphology changes. Furthermore, a comparative UPLC analysis of PG fragments isolated from D. indicus cells propagated in different growth media revealed alterations in the PG composition. An increase in the overall cross-linkage of PG was observed in muropeptides from nutrient-rich TSB and NB media versus PYE medium. Overall our study highlights that environmental conditions influence PG composition and cell morphology in D. indicus.
Highlights
Deinococcaceae family is among the few groups of bacteria that are ubiquitously distributed in the environment
Further examination revealed that D. indicus displayed small rod-shaped cells in PYE growth medium and multi-cell chains in Luria Bertani broth (LB), Tryptone soy broth (TSB), and Nutrient broth (NB) media (Figure 1)
It is plausible that cell morphology changes could be a result of differential growth rate of D. indicus in various growth media
Summary
Deinococcaceae family is among the few groups of bacteria that are ubiquitously distributed in the environment. The members of this family are aerobic, non-spore forming, chemo-organotrophs that display extreme resistance to UV/gamma radiation as well as desiccation (Cox and Battista, 2005). Members of family Deinococcaceae have a complex cell envelope. D. radiodurans has an unusual multilayered cell envelope, which includes a thick peptidoglycan layer, an outer membrane like lipid layer, and a S-layer (Battista, 1997; White et al, 1999). The TAM consists of two components TamA and TamB that form a complex essential for assembly of several outer membrane proteins (Webb et al, 2012). Multiple cell formation was previously reported in Deinococcus radiodurans where it was seen that cell growth and division took place without separation, creating a cluster of cells (Chou and Tan, 1991)
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