Investigation Of Biofilm Formation And Its Characteristics In Staphylococcus Aureus During Glycobiological Chemical Engineering

Food safety in food fermentation processes (a glycobiological chemical engineeringoperation unit) is a major concern in people’s daily life. In the field, various kinds ofbiological and chemical or acute and chronic hazards have received much attention with theimprovement of life quality. In nature, microorganisms grow predominantly as biofilms onsurfaces. Biofilms are a key potential hazard of food safety and hygiene, and also a majorsource of product contamination. Microbes change their growth mode to form biofilms, whichleads to survival of microbes under regular anti-bacterial processes and causes foodcontamination, and antibiotic resistance and advanced glycation end products (AGEs). It iswell documented that biofilm has become a serious problem in food industries and food safety.In addition, potential chemical hazards-AGEs in biofilm should not be neglected with its closerelationship with aging, diabetes and other diseases.Based on biofilm hazards in food fermentation industry, prevalent Staphylococcus aureus(S. aureus) strains in Guangzhou were used to study their biofilm formation. The study aimedto detect and identify the strain, investigate the prevalance of phenotype and genotypebackgrounds and biofilm formation, determine the Nε-(carboxymethyl)lysine (CML) contentof biofilms in MRSA strains in order to pre-propose and eliminate various potentialfood-borne safety issues during food production and sugar production. The main contents ofthis study were as follows:(1) The prevalence of S. aureus was investigated and analyzed systematically viadetection and identification of bacteria. This study used a multiplex-PCR assay to detectstaphylococci, S. aureus and mecA resistance in127staphylococci strains. According to theresults,119and8strains were found to be S. aureus and coagulase-negative staphylococci.107out of119S. aureus and6out of8coagulase-negative staphylococci carried mecA gene,which showed resistance to methicillin. And the methicillin-resistance S. aureus (MRSA)detection rate reached89.9%. In conclusion, for the prevalent S. aureus isolates, antibioticresistance was an obvious characteristic.(2) The phenotype and genotype backgrounds were investigated in prevalent S. aureusstrains, including genome islands-SCCmec and antigrams. First, SCCmec types wereidentified in113meticillin-resistant staphylocci by multiplex PCR. The results indicated thatof the107MRSA strains,12,72,10and11carried type II, III, IV and V SCCmec respectively,one strain couldn’t be typed, in addition, one strain might harbor2-3kinds of SCCmec types.Of the6MRCNS strains, one carried type III SCCmec,5strains couldn’t be typed. Antibiotic susceptibility test was perfomed in119S. aureus. The antibiotic resistance patterns revealedthat all MRSA isolates showed a high frequency of multidrug resistance, i.e. up to74.8%ofthe isolates showed multiresistance to≥9kinds of antibiotics. All the MRSA strains testedwere multiresistant to≥5antibiotics, whereas all the meticillin-susceptible S. aureus (MSSA)strains were multiresistant to≤7antibiotics. There were two MRSA strains which showedimmediate sensitiveness to teicoplanin and linezolid, respectively. In conclusion, most of theprevalent strains came from hospitals with the same prevalence in Asian countries (exceptJapan and Korea) whose SCCmec elements were larger, evolved more slowly, had strongerantibiotic resistance but lower toxicity and always no toxin genes. However,community-acquired S.aureus has increasd dramatically in recent years whose SCCmecelements were smaller, evolved more quickly, had lower antibiotic resistance profiles, buthigher toxicity and always many toxin genes. The study found that prevalent S. aureus hadexceeded the limitations of traditional hospitals with a significant increase incommunity-acquired S. aureus, which was consistent with the international research. From the1990s, community-acquired S. aureus had been reported worldwide, a trend to replacehospital-acquired S. aureus with the isolation rate rises gradually.(3) Biofilm formation was determined in119S. aureus strains. According to the results,all strains have the ability to form biofilm in multiwell plates. Of the107MRSA strains,37.5%(42/107) could form moderately or fully adherent biofilms. Of the12MSSAstrains examined,41.7%(5/12) could also form moderately or fully adherent biofilms.When these results were compared using the statistical tests, there was no significantdifference in biofilm formation between S.aureus solates that were susceptible andresistant to meticillin (P=0.77). Moderate or stronger biofilms were observed for75%of type II SCCmec, while such biofilms were only responsible for37.5%,30%and18.2%of type III, IV and V SCCmec, respectively. Based on the results, MRSAstrains of type II SCCmec had higher biofilm forming ability.(4) The MRSA strain with highest biofilm formation was selected for the investigationof CML in biofilms. The results demonstrsted the content of CML in biofilms went up as theculture time increased, and growth rate was higher during24-48h. In conclusion, potentialchemical hazards (AGEs) posed a new threat to our human beings’ health besides food safetyconcerning individual mciroorgannism.