KA­RIN HOLM­FELDT: Who is kil­ling your bug - Vi­ral sto­ries from aqua­tic en­vi­ron­ments

Who is killing your bug - Viral stories from aquatic environments

Ka­rin Holm­feldt

Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden

Vi­ru­s­es on earth have been esti­ma­ted to be 10 bil­li­on more nu­merous than all the stars in the uni­ver­se and the ma­jo­ri­ty of the­se vi­ru­s­es in­fect mi­cro­bes. In aqua­tic en­vi­ron­ments they com­mon­ly out­num­ber their mi­cro­bi­al hosts ten-fold and through host spe­ci­fic in­fec­tion and ly­sis they are im­portant for mi­cro­bi­al mor­ta­li­ty and di­ver­si­fi­ca­ti­on with cas­ca­ding eco­lo­gi­cal ef­fects. By com­bi­ning iso­la­ted vi­rus-bac­te­ria mo­del sys­tems and high-through­put se­quen­cing, the mys­te­ries of vi­ral di­ver­si­ty, func­tio­na­li­ty, ac­tivi­ty, and host in­ter­ac­tions have star­ted to be un­ra­ve­led.

Here I will gui­de you through an unusual­ly di­ver­se sys­tem of twel­ve dif­fe­rent vi­ral ge­ne­ra, in­clu­ding both dou­ble- and sin­gle-stran­ded DNA vi­ru­s­es, all in­fec­ting the same bac­te­ri­al spe­cies, the aqua­tic Flav­o­bac­te­ri­um Cellulophaga baltica. The­se vi­ru­s­es are not only ge­ne­ti­cal­ly di­ver­se but also re­pre­sent a wide va­rie­ty of host in­ter­ac­tions, ran­ging from ge­ne­ra­lists to spe­cia­lists, but also pro­vi­des in­for­ma­ti­on on how vi­ral in­fec­tion also can be mo­du­la­ted by the host they in­fect. Fur­ther, the­se vi­ru­s­es may chan­ge the hos­t’s func­tio­na­li­ty, both du­ring in­fec­tion but also in the re­sis­tant mi­cro­bi­al po­pu­la­ti­on sur­vi­ving vi­ral in­fec­tion. Over­all, the les­sons lear­ned from this mo­del sys­tem has lar­ge­ly im­pro­ved our un­der­stan­ding of the in­tri­ca­te in­ter­ac­tions oc­cur­ring among the smal­lest bio­lo­gi­cal play­ers in the oce­ans.