Induction of Maltose Release by Light in the Endosymbiont Chlorella variabilis of Paramecium bursaria

Genome sequences of Chlorella sorokiniana UTEX 1602 and Micractinium conductrix SAG 241.80: implications to maltose excretion by a green alga

“…The strain was obtained from the Algal Culture Collection of the Plant Physiology Institute, University of Goettingen, Germany, where it was originally deposited in 1974. Our experiments compared extracellular sugar production by M. conductrix SAG 241.80 and C. sorokiniana UTEX 1602 at pH 5.7 and 7.6 with what has been previously reported for other sugar‐releasing strains (Dorling et al ., ; Shibata et al ., ). The results illustrated the stark differences in the phenotypes for M. conductrix SAG 241.80 grown at the two pH conditions tested (pH 5.7 and 7.6) as well as in comparison to C. sorokiniana UTEX 1602 (Figure ).…”

“…A recent report looked at the release of maltose by the P. bursaria endosymbiont Chlorella variabilis F36‐ZK in relation to light and culture medium pH (Shibata et al ., ). Nearly all of the extracellular sugar released by C. variabilis F36‐ZK is in the form of maltose (Kamako and Imamura, ), similar to our findings with M. conductrix SAG 241.80.…”

“…The accumulation of maltose in symbiotic algae has been described in a number of species (Cernichiari et al ., ; Ziesenisz et al ., ; Mews and Smith, ; Matzke et al ., ; Kessler et al ., ; Brechignac and Schiller, ; Dorling et al ., ; Hoshina et al ., ; Shibata et al ., ). While the accumulation of maltose or glucose in the culture medium is well documented, a clear understanding or even a simple pathway for the production of maltose for the purpose of sustaining this pathway and the association between the algae and the host is still lacking, even following more than 100 years of research in this field (Hoshina et al ., ; Pröschold et al ., ).…”

“…The release of sugars to the extracellular space in certain strains of green algae isolated from symbiotic associations is well documented (Mews and Smith, ; Douglas and Smith, ; Matzke et al ., ; Kessler et al ., ; Brechignac and Schiller, ; Dorling et al ., ; Summerer et al ., ; Shibata et al ., ). Algae isolated from symbiotic associations are often maintained within perialgal vacuoles inside the host.…”

“…However, the molecular mechanism of maltose secretion in relation to acid tolerance of growth and symbiotic ability still remains poorly understood for symbiotic algae in these associations. These specific associations are of interest for developing an understanding of the pathways and regulation of sugar production and export, which includes efforts to uncover the specific pathways utilized to biosynthetically construct and direct these sugars outside of the algal cell (Shibata et al ., ). Such knowledge might lead to the potential application of these algae for the production of sugars through algal biotechnology (Brechignac and Schiller, ; Ducat et al ., ).…”