Bacteria survived 30,000 years

How bacteria survived during a 30,000 years long winter

The bac­te­ria in the Siber­ian per­mafrost have been stud­ied and found to have sur­vived hiber­nat­ing for up to 30,000 years—much longer than com­mon­ly assumed. What do they do dur­ing that time? How can they survive?

Read on to find out more amaz­ing facts about how bac­te­ria sur­vived a 30,000 years-long Siber­ian winter.

How could bacteria survive during a 30,000 years-long winter?

Bacteria survived 30,000 years

Researchers have come across strains of bac­te­ria in the Siber­ian per­mafrost that have sur­vived over 30,000 years, which is much longer than pre­vi­ous­ly expected.

A num­ber of bac­te­r­i­al strains have been found to be pro­tect­ed inside the per­mafrost at a depth of between 500 and 2,000 meters (1,640 and 6,562 ft) below the sur­face. The sam­ples were col­lect­ed in south­west­ern Siberia and are found to be almost iden­ti­cal to those found in North Amer­i­ca’s sub­arc­tic regions.

These bac­te­ria sur­vive by hiber­nat­ing dur­ing sum­mer months when tem­per­a­tures rise above ‑20°C and per­sis­tent freez­ing con­di­tions pre­vail. Researchers spec­u­late that this could be due to a com­bi­na­tion of the extreme­ly cold win­ter tem­per­a­tures and the bac­te­ri­a’s abil­i­ty to sur­vive for long peri­ods of time with­out oxygen.

Most strains iden­ti­fied in the study do not con­tain any DNA or genet­ic infor­ma­tion. How­ev­er there are some strains that do have DNA in them. The researchers call these “pro­tists” because they con­tain intra­cy­to­plas­mic organelles and have like­ly lost their own DNA.

The team who dis­cov­ered this says that it is “like­ly that pro­tist com­mu­ni­ties are extreme­ly resilient to sea­son­al freeze–thaw cycles. It seems that the pro­tists remain alive and in dynam­ic dis­e­qui­lib­ri­um with their sur­round­ing water in the per­mafrost. This implies that these com­mu­ni­ties have an active meta­bol­ic activ­i­ty deep in the per­mafrost. This is some­thing that has been pre­vi­ous­ly impos­si­ble to observe.”

Also read: Are plants con­scious in a sim­i­lar way as animals?

How could there be organisms preserved inside a deep frozen layer?

Frozen lake

Sub­ter­ranean envi­ron­ments are found beneath a range of dif­fer­ent types of sub­strates includ­ing soil, rocks and ice. In this so-called sub­arc­tic envi­ron­ment where tem­per­a­tures can get up to ‑35°C, much of it is like­ly to be cold enough for microbes to survive.

How­ev­er, the researchers think that the main rea­son why this area is such a hotspot for per­mafrost preser­va­tion is that the region has seen very lit­tle dis­tur­bance at ground lev­el, allow­ing for the soil to be pre­served in its frozen state. The Siber­ian area has also been large­ly left alone since the last Ice Age.

This means that any liv­ing organ­ism dis­cov­ered must have adapt­ed to sur­vive under these con­di­tions. In fact, it’s like­ly that only a few microor­gan­isms have sur­vived over time in sub­arc­tic regions like these. These hardy organ­isms are resis­tant to freez­ing and are able to hide inside ice crys­tals until con­di­tions start improv­ing again.

Permafrost

Per­mafrost is ground that remains frozen for sev­er­al con­sec­u­tive years. It typ­i­cal­ly occurs in high­er lat­i­tudes and high alti­tude loca­tions where the mean annu­al air tem­per­a­ture remains below freezing.

It’s formed because the ground stays cool year-round while the sur­face lay­er freezes each win­ter. Over time, organ­ic mat­ter starts to decom­pose and forms a lay­er of peat humus. It remains trapped under­neath a frozen sol­id lay­er above.

Esti­mates sug­gest that as much as 20% of the land in the North­ern Hemi­sphere con­tains per­mafrost. This equates to 1.6 mil­lion square kilo­me­ters (625,000 square miles).

Concluding paragraph

So, while the notion that bac­te­ria can sur­vive in a win­ter­less cli­mate may seem like old news, these dis­cov­er­ies show that dur­ing long-term timescales, microor­gan­isms can sur­vive in the most extreme conditions.

It’s pos­si­ble that human­i­ty has yet to dis­cov­er any microor­gan­isms from the deep­est cold bios­phere locat­ed in the Siber­ian per­mafrost. How­ev­er, this find­ing does rein­force why it’s impor­tant to pre­serve such regions for future study. After all, it could pro­vide us with clues as to how oth­er life forms have evolved in extreme environments.

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