HYBRID EVENT: You can participate in person at Rome, Italy or Virtually from your home or work.

2nd Edition of International Conference

and Expo on Clinical Microbiology

June 23-24, 2023 | Rome, Italy

ICCM 2022

AC Matin

Speaker at Clinical Microbiology 2022 - AC Matin
Stanford University, United States
Title : Managing bacterial eradication in disease and survival for life support systems on Earth and space


Bacteria like Escherichia coli cause disease but are also beneficial in resource regeneration. Its UPEC strain causes cystitis, which is treated by gentamicin. The protein ss, encoded by the rpoS gene, controls E. coli resistance to antimicrobial agents. We discovered that rpoS deletion mutation renders UPEC more sensitive to Gm and other bactericidal antibiotics; proteomic analysis suggested a weakened antioxidant defense as the cause. Reactive oxygen species (ROS) detectors (psfiA gene reporter, and appropriate chemicals) indicated greater ROS generation by Gm in the mutant. When administered along with an antioxidant, or under anaerobic conditions (that prevent ROS formation), Gm was less lethal to the mutant. In vivo studies of treating UPEC infection of mice bladder gave similar results. Thus, oxidative stress produced by insufficient quenching of metabolic ROS accounted for greater sensitivity of the mutant. Gm exposure to other E. coli mutants, missing antioxidant proteins, also resulted in greater ROS production and lethality; these lacked the ROS quencher proteins, (e.g., SodA/SodB; KatE/SodA), or the pentose phosphate pathway proteins, which provide NADPH (e.g., Zwf Gnd; TalA) required by the quencher proteins. Use of a microfluidic device indicated that the results applied at a single cell level. Gm’s lethality in bacteria is due to inhibition of protein synthesis, but most current UPEC patient isolates can overcome this (reflecting the larger problem of growing bacterial antibiotic resistance). Therefore, these findings provide a timely means of restoring Gm effectiveness by curbing bacterial antioxidant defense. Using bioinformatics, we have identified several small molecules that inhibit ss and can overcome bacterial Gm resistance. In space flights, astronauts often suffer from cystitis; further, bacterial antibiotic resistance is a greater threat to them as microgravity (MG) impairs human immune response.
Bacterial gene regulation can differ in normal vs. MG. However, the “EcAMSat” Stanford/NASA mission showed that ss controls Gm resistance also in MG. This work employed a free flying “nanosatellite” equipped with a sophisticated microfluidic system, which autonomously analysed UPEC sensitivity to Gm in space flight over several days and transmitted the results by telemetry to Earth in real time. Bacterial multidrug resistance, such as the one regulated by the emrRAB operon and the EmrR protein, is a major public health problem. Its activation is due to alteration in the EmrR protein structure by antibiotics, which too can be prevented by small molecules and bioinformatic approaches. For long-term space flights and space colonization, ecosystems need to be established for resource regeneration and waste recycling, processes in which E. coli is important. Manipulation of ss levels and the resistance proteins it controls hold the key for stabilizing this bacterium under MG conditions. Several scientists have contributed to this work; they will be recognized in the presentation


Dr. Matin has been a full professor at Stanford University for several years and is affiliated with several programs, including the Stanford Cancer Research Institute. He has contributed to many areas of biological research, including discovery of new drugs and therapeutic enzymes and their improvement as well as their specific targeting to cancer (and other diseases). He did his Ph. D. at UCLA, spent some years in the Netherlands (State University of Groningen), where he directed a research group, before joining Stanford. He is recipient of numerous awards and honors.