 the bacteria under normal and low shear modeled microgravity ([Figs. 2](#f0010){ref-type="fig"} and [3](#f0015){ref-type="fig"}). Low shear modeled microgravity did not alter the morphology of *S. pyogenes* as no significant differences in size and shape could be observed from the TEM and SEM images and extracellular matrix formation was also not noticeable. The sensitivity of bacteria grown under normal gravity to antibiotics was analyzed and the alteration in the antibiotic sensitivity of low shear modeled microgravity grown bacteria was compared ([Table 1](#t0005){ref-type="table"}). The results obtained indicated that *S. pyogenes* was resistant to hygromycin producing no zone of inhibition of growth. Ampicillin produced highest zone of inhibition, overlapping zones were produced when higher concentrations of 50, 100, 150, 200 μg/disc were used, so the concentration of ampicillin was reduced to half and discs of final concentrations of 25, 50, 75, 100 μg/disc were prepared and the antibiotic sensitivity test was carried out.

The *S. pyogenes* grown under normal gravity and low shear modeled microgravity at 37 °C were tested for thermal stress tolerance 45 °C, 50 °C and 55 °C in incubators for 30 min. The percentage of cells survived after 30 min of thermal stress were estimated and presented in the [Fig. 4](#f0020){ref-type="fig"}. The bacteria cultured under low shear modeled microgravity showed higher resistance to thermal stress of 45 °C and 50 °C as compared with the culture grown under normal gravity. Both the cultures grown under low shear modeled microgravity and normal gravity could not resist thermal stress when exposed to 55 °C for 30 min. The alteration of low shear modeled microgravity grown *S. pyogenes* to oxidative stress using 30 mM hydrogen peroxide was analyzed and given in [Fig. 5](#f0025){ref-type="fig"}. Low shear modeled microgravity cultures resisted the thermal stress more than normal gravity grown cultures, but the oxidative stress resistance was decreased when