# _Pseudomonas aeruginosa_ Response to Acidic Stress and Imipenem Resistance
## 4 Discussions  
_P. aeruginosa_ is characterized as an opportunistic pathogen and is one of the major causes of food spoilage; especially in fruits and fruit juices, dairy products, fish, and meat products [27; 28].Bacteria generally struggle to survive high sugar levels, acidic pH, oxidative stress (Eh), and low water activity (aw) [15; 29; 30]. However, some pathogens such as _P. aeruginosa_, not only develop tolerance to such harsh environmental conditions,  
Figure 4: Bar diagram indicating the percentage of SGCP and NCP under impenem stress and without impenem stress on the established biofilms. Statistics of mean and standard deviation were applied to access the degree of shift of phenotype. The level of significance of the data (\(p<0.0001\)) is represented by ****. Figure 3: Crystal violet (CV) staining of biofilms formed by _P. aeruginosa_. Cell-bound crystal violet was dissolved in 33% acetic acid. Biofilm thickness (OD) was measured at 570 nm. (**a**) Slides were placed in 0.1% CV solution for 25 min. (**b**) Slides were washed twice with 1 mL of sterile saline and dried at room temperature. but also thrive in them [31; 32]. They apply different strategies to survive in difficult environmental conditions, and formation of biofilm is one of these tactics. Biofilms are heterogeneous congregations of surface-associated microorganisms, encapsulated within a self-produced polymer matrix, consisting of polysaccharides, protein, and DNA [33; 34]. The matrix acts as a physical barrier against antimicrobial compounds and provides a protective ecological niche for the survival of microorganisms. A single species of bacteria or consortia of multispecies microbes can exist within a biofilm. Many microorganisms can build biofilms, e.g., _Mycoplasma pneumoniae, Candida albicans, Staphylococcus epidermidis, Mycobacterium tuberculosis, Mycobacterium abscessus_, and _Staphylococcus aureus_[15; 35; 36; 37; 38; 39]. Biofilms pose serious health concerns, due to the recalcitrant nature of microbes towards antimicrobial drugs and host immune responses. Moreover, biofilms evade the immune system through their exopolymer matrices and arrangement. Immune evasion coupled with multidrug resistance may effectively complement the virulence of a pathogen. Therefore, the prevention and suppression of biofilm formation is of utmost importance [40; 41]. The present study exhibited the presence of _P. aeruginosa_ in concentrated fruit juice samples, with a strong potential for biofilm formation, reduced metabolism, and slow growth rate, to survive a low pH and antibiotic stress. They retained the ability for reversion to the normal colony phenotype when the stress was relieved, as reported previously [42; 43; 44]. _P. aeruginosa_ is also capable of long-term survival without nutrients, by existing in a dormant state [45]. This dormant phenotype not only survived starvation, neutralized toxicity, but also demonstrated resistance against multiple antibacterial agents [46]. The other characteristic feature demonstrated by the subject strain is heterogeneity. This means that a small fraction of the population survived and the majorities of cells either died or were unable to grow in a particular environment [47]. This is a well-established characteristic of pathogens such as methicillin heterosexual _Staphylococcus aureus_[48] and Carbapenems heterosexual _Acinetobacter baumannii, Enterobacteriaceae cloace, Klebsiella pneumoniae, Escherichia coli_, and _P. Aeruginosa_[49]. Notably, these surviving cells did not produce a noticeable change/deterioration in the quality of the product. This dormancy, a form bet-hedging, is a process used by a wide range of microbial taxa, and refers to an organism's ability to enter a reversible state of low metabolic activity when faced with unfavorable environmental conditions. Similarly, previous reports showed that starvation, antibiotics, and environmental stressors applied to microbial populations resulted in the induction of persister or dormant cells [45; 47; 50]. Our study suggested that _P.