Rawdata_Yersinia.xlsx

The limits of life
of aerobic microorganisms are well understood, but the responses of anaerobic
microorganisms to individual and combined extreme stressors are less well
known. Motivated by an interest in understanding the survivability of anaerobic
microorganisms under Martian conditions, we investigated the responses of a new
isolate, Yersinia intermedia
MASE-LG-1 to individual and combined stresses associated with the Martian
surface. This organism belongs to an adaptable and persistent genus of
anaerobic microorganisms found in many environments worldwide. The effects of
desiccation, low pressure, ionizing radiation, varying temperature, osmotic
pressure, and oxidizing chemical compounds were investigated. The strain showed
a high tolerance to desiccation, with a decline of survivability by four orders
of magnitude during a storage time of 85 days. Exposure to X-rays resulted in
dose-dependent inactivation for exposure up to 600 Gy while applied doses above
750 Gy led to complete inactivation. The effects of the combination of
desiccation and irradiation were additive and the survivability was influenced
by the order in which they were imposed. Ionizing irradiation and subsequent
desiccation was more deleterious than vice versa. By contrast, the presence of
perchlorates was not found to significantly affect the survival of the Yersinia strain after ionizing
radiation. These data show that the organism has the capacity to survive and
grow in physical and chemical stresses, imposed individually or in combination
that are associated with Martian environment. Eventually it lost its viability
showing that many of the most adaptable anaerobic organisms on Earth would be
killed on Mars today.