# Evaluation of the Adhesive Potential of Bacteria Isolated from Meat-Related Sources
## 3 Results and Discussion  
Bacterial biofilm formation is the source of microorganism cross-contamination in the food industry. This study involved 14 meat-borne bacteria for the biofilm-forming assay. Since the optimal temperature of each genus varies, an average of 30 \({}^{\circ}\)C was proposed to be used for coordination, while 20 \({}^{\circ}\)C was applied in order to simulate a lower environmental temperature that occurs during processing in some food facilities. Both short-term and long-term formations of biofilm were investigated by adjusting the incubation time to 24 h and 72 h. Results showed that all of the bacteria were able to attach to the polystyrene surface with a variation which revealed the differences among genera and within species (Figure 1). _A. salmonicida_ displayed the best adhesive performance, regardless of time and temperature, with a consistency between the two isolates (_A. salmonicida_ I and II), while a moderate amount of biofilm was exhibited by _A. veronii_, indicating a species-specific distinction. A similar finding was observed when studying the adhesive strength of 14 _Aeromonas_ trains ([PERSON] et al., 2018). Except _P. putida I_, all strains of _Pseudomonas_ (including _P. putida_ II) formed considerable amount of biofilms at 20 \({}^{\circ}\)C for 24 h, whereas at 72 h, a higher temperature was more favorable for attachment of these bacterial cells. The different behaviors presented by _P. putida_ I and _P. putida_ II were in contrast to the case of _A. salmonicida_, this phenomenon demonstrated that isolates of one species are not necessarily supposed to perform in the same way. As for the other strains tested, a relatively strong biofilm-forming capacity was obtained in both _C. braakii_ and _S. liquefaciens_ at 30 \({}^{\circ}\)C for 24 h or 72 h, respectively, while the _Lactobacillus_ genus was so \"modest\" that it formed the least amount of biofilm whether it was on the first day or the third day. This might result from the alternation of substratum. _Lactobacillus_ is recognized as inhabitants in the human gastrointestinal tract where surface proteins can take advantage of mediating adhesion with the help of mucus ([PERSON] et al., 2018). However, the polystyrene surface used for the present in vitro experiment is of significant difference to the epithelial one, so that related proteins could be limited to play their original utility. The performance of biofilm formation was temperature-dependent. At 24 h, nine bacteria among the fourteen displayed a high attachment under 20 \({}^{\circ}\)C compared to 30 \({}^{\circ}\)C, especially _R. aauqtilis_, _E. coli_, and the _Pseudomonas_ species, showing a significant advantage. This phenomenon was probably due to the diversity of optimal temperature of the strains engaged. A large cell density in culture broths results possibly in providing a comfortable environment for bacterial communication, thus enhancing the attachment of bacteria ([PERSON] et al., 2018). The dynamic process of attachment evolved as time went on and 48 h later, and a great variation was observed at 72 h. More bacteria showed a stronger biofilm-forming ability at 30 \({}^{\circ}\)C, especially _S. liquefaciens_, _Pseudomonas_ isolates _ putida_ II, _fluorsecces_, and _fragi_, which formed markedly improved amounts of biofilm and even exceeded that on the first day. Meanwhile, _A. veronii_ maintained steady and a slightly fluctuated gap of biofilm amount between the two temperatures tested. Additionally, less biofilm of few isolates represented by _A. salmonicida_ and _C. braakii_ was observed at 72 h than 24 h, probably due to the biofilm dispersal at the end of incubation periods. The results above indicated that incubation