1. APPLICATION OF S-LASCA AND T-LASCA FOR MONITORING OF GROWTH OF BACTERIAL COLONIES Onega Ulianova, Saratov State Agrarian University, RUSSIA Sergey Ulyanov, Saratov State University, RUSSIA

2. Purposes of investigations adaptation of the method of analysis of temporal and spatial contrast of speckle fields emerging in the scattering of coherent radiation in the bacterial colonies (s- LASCA and t-LASCA) to monitor the growth and structure of the colonies of bacteria

3. Typical examples of the growth of a culture of E. coli B6 on dense bactoagar

7. Experimental set-up for investigations of dynamics of growth of bacterial colonies by method LASCA.

8. Sample, under the investigations by means of LASCA-microscopy.

9. Algorithm of processing of dynamic speckle fields where I is the instantaneous intensity of dynamic biospeckles, σ I is the standard deviation of fluctuations of intensity. Angle brackets denote an average over time. To reduce the level of noise, the averaging over 100 realizations has been used when registering a dynamic speckle fields has been performed.

10. Image, obtained using t-LASCA. Image has been recorded at illumination of 2- days old colony E. сoli. Observation has been performed using 8 x microobjective

11. Image, obtained using t-LASCA. Image has been recorded at illumination of 2- days old colony E. сoli. Observation has been performed using 20 x microobjective

12. Image, obtained using t-LASCA. Image has been recorded at illumination of 2- days old colony E. сoli. Observation has been performed using 95 x microobjective

13. Image, obtained using s-LASCA. Image has been recorded at illumination of 2- days old colony E. сoli. Observation has been performed using 8 x microobjective

14. Image, obtained using s-LASCA. Image has been recorded at illumination of 2- days old colony E. сoli. Observation has been performed using 20 x microobjective

15. Image, obtained using s-LASCA. Image has been recorded at illumination of 2- days old colony E. сoli. Observation has been performed using 95 x microobjective

16. Observation has been performed using 20 x microobjective Control: LASCA-image, obtained at illumination of clean bactoagar (no bacterial colonies) by coherent light.

17. Controle: LASCA-image, obtained at illumination of clean bacto-agar (no bacterial colonies) by coherent light. Observation has been performed using 95 x microobjective

18. Conclusions Experimental research demonstrate the possibility of using methods of t-LASCA and s-LASCA to monitor the growth of bacterial colonies. However, influence of speckle-modulated biospeckles on the results of measurements of the speed of growth of bacterial colonies have identified substantial difficulties in the practical application of these methods It turned out that the influence of scattering in agar is extremely large. It is very hard to differentiate between the influence of speckles, generated by moving particles in bactoagar and contribution to the dynamics of speckles arising from the structural changes of growing colony.