Recovery of Stressed Escherichia coli Culturability using Selective Media with Penicillin Binding Proteins for Bioburden Testing

Abstract

This study aimed to assess the effectiveness of selective media enriched with Penicillin-binding proteins (PBPs) in bioburden testing and the recovery of stressed Escherichia coli. Five distinct E. coli strains were subjected to experimentation utilizing two antibiotics to induce stress, simulating real-world scenarios where bacteria face various stressors, including antibiotics. The deliberate stress induction aimed to observe how stressed bacteria respond and recover in the presence of PBPs, vital cell wall components targeted by antibiotics. Multiple antibiotics ensured a comprehensive evaluation of stress responses. PBP1 tended to have a milder inhibitory effect on bacterial growth compared to both PBP2 and PBP3 across various growth media and strains. PBP2 demonstrated variable effects, displaying a nuanced impact depending on the growth medium and strain. In contrast, PBP3 consistently exerted a stronger inhibitory effect on bacterial growth. The strain of E. coli exhibited a significant influence on growth characteristics, reflecting strain-dependent responses to experimental conditions. Growth media and specific PBPs also displayed notable effects on colony forming units (CFUs) and percentage recovery (PR). Modified media generally supported higher CFUs and PR compared to standard media, showcasing the importance of media composition. Buffer choice also significantly impacted CFUs and PR, underlining the need for careful buffer standardization. Overall, the type of PBP used significantly affected E. coli colony numbers, as indicated by a highly significant p-value (p≈2.04×10-16). This study’s insights into the impact of selective media, PBPs, and bacterial strains on stressed E. coli recovery contribute to optimizing recovery protocols in microbiological studies. Comparisons between penicillin and cefixime treatments revealed higher CFU values in modified media, indicating their efficacy. Different PBPs showcased variations in CFU and PR, emphasizing their role in stressed E. coli recovery. The study sheds light on the multifaceted interactions between antibiotics, PBPs, media, and bacterial strains, vital for understanding antibiotic responses. These findings provide critical insights into designing effective recovery strategies and advancing microbiological studies.