Impact of Hyperthermia on Gut Microbial Adaptation: Role of Thermophilic Bacteria in Host Physiology

Background: Heat stress (HS) is one of the most challenging environmental conditions, responsible for impaired growth and reproduction in living systems. It also leads to altering the release of different biochemicals responsible for controlling the metabolic pathway.

Methods: Five White Wistar rats were exposed at 42±1℃ inside a closed chamber for the induction of hyperthermia. Their rectal temperature was recorded before and after heat exposure. The semi-digested food from the gut (colon) of sacrificed rats was collected under sterilized conditions for the isolation of gut bacteria on a nutrient agar plate at 50 ℃, 60 ℃, and 70 ℃. The sample was incubated for 24 hours, and isolates were further purified. The proteolytic, amylolytic, cellulolytic, and xylanolytic activities were measured via the plate assay, and the enzymatic index was calculated. Total protein and estimation of HSP70 were also quantified.

Results: Initially, the rats’ rectal temperature was 37.1±0.2 ℃, but after exposure to heat, the temperature was 40.8±0.2 ℃. The number of purified isolates was recorded, i.e., at 50 ℃ (04), at 60 ℃ (01), and at 70 ℃ (03). Among eight isolates, Bacillus licheniformis (50 ℃) showed all four enzymatic activities with a higher enzymatic index. Further, this novel isolate also exhibited maximum concentration of HSP70.

Conclusions: This study revealed the survival of a novel bacterium (B. licheniformis) capable of producing key metabolites, highlighting its significance in supporting host physiology and heart health. As a probiotic, it may serve as a potential therapeutic bridge connecting HSP70, cardiac function, and gut health.