Formation And Characteristics Of Biofilms In Food Processing Network Management Material Under Oligotrophic And Eutrophic Conditions

Fouling hazards caused by biofilm in food processing can not be ignored.It is necessary to study the law and characteristics of the formation of microbial membrane in food processing and food processing network under different nutrition materals.Through to the food processing environment and provide a theoretical basis for the effective control of the biofilm,provide effective protection of food safety.So as to effectively control the residual pollution of biofilm in the process of food processing.Therefore,in this paper using two different nutritional status matrix environment(water)-oligotrophic and eutrophic(Yakult yoghurt),the formation ability of biofilm and the influencing factors of biofilm formation under different trophic status were studied,and the secretion of extracellular substance in biofilm was measured.The main results are as follows:(1)The growth curve of biofilms under different nutrition conditions.The growth curve of biofilm bacteria and the adhesion of biofilm under microscope were studied under the condition of oligotrophic state and eutrophic state.The results show that the oligotrophic and eutrophic condition,biofilm formation is a dynamic process,it can be divided into three stages:cell adhesion and growth stage,mature stage of biofilm,biofilm degradation stage.Under oligotrophic conditions,the number of biofilm forming bacteria grew rapidly at 0-3 days,and the maximum number of biofilm bacteria produced in fifth days was 4.39 lg cfu/cm~2.In the eutrophic state,the number of biofilm bacteria in lactic acid bacteria reached the maximum at third days,and was6.79 lg cfu/cm~2.(2)Study of adhesion during biofilm formation.The crystal violet staining method semi quantitative method combined with biological microscope to observe the biofilm formation adhesion process.The number of adhered bacteria was positively correlated with culture time,and the maximum amount of adhesion was observed at the mature stage of biofilm,and the thicker the biofilm was.Oligotrophic conditions,biological bacteria membrane increased with the prolonging of incubation time,to third days,the number of bacteria biofilm adhesion was increased significantly and the aggregation phenomenon began to appear,poly colony cluster,showed the formation of biofilm.By fifth days,the aggregation phenomenon was more obvious.The colonies clustered and the biofilm thickness increased.Subsequently,the biofilm was degraded markedly,and the phenomenon of aggregation and clustering began to decline.The thickness of biofilm decreased significantly and the phenomenon of scattering occurred.In the eutrophic state,the amount of biofilm formation increased significantly with time,and the biofilm formed in third days was the most.However,the amount of biofilm was gradually declined and began to degrade.The semi quantitative results of crystal violet staining showed a consistent trend with the growth curve.(3)The influencing factors of biofilm in different nutrition states.The formation laws of biofilm in oligotrophic state and eutrophic state were studied by factors such as temperature,carrier material and fluid status.The results show that the oligotrophic condition,temperature had significant effects on biofilm formation,25~35?unit area formed by the amount of the film increased gradually with the increase of temperature,the temperature is too high will inhibit the formation of biofilm.The stainless steel sheet has the largest amount of adhesion,followed by the plastic sheet,PP,and finally the slide.The biomass of biofilm is higher in static state than in biofilm under dynamic condition.According to the experiment results,under the oligotrophic condition,the optimum growth conditions of biofilm were as follows:incubation time was 5 days,culture temperature was 35?,carrier material was stainless steel,and the fluid state was static.Eutrophication,biological production of membrane was increased with incubation time and temperature increased,after reaching a certain value in the stable stage,then decreased gradually,showed a trend of trapezoid;biological adhesion amount is film on the stainless steel sheet is the largest,followed by the PP film,and finally the slide rest;the amount of training under the condition of adhesion and biofilm than flow culture.According to the experimental results,the optimum growth conditions of the biofilm under the eutrophic state were as follows:the incubation time was 3 day,the culture temperature was 30?,the carrier material was stainless steel,and the fluid state was static.(4)Study on the secretion of extracellular substances under different nutritional conditions?In the course of biofilm formation,the secretion of extracellular substance in different nutrition states was measured with the prolongation of incubation time.The research shows that the formation of biofilm process will continue to secrete extracellular substance,and the secretion of extracellular substances increased with the increase of time;oligotrophic condition,extracellular polysaccharide secretion in fifth days the most.21.43 mg/mL,extracellular protein secretion in fifth days up to 16.86mg/mL;under eutrophic condition,extracellular polysaccharide secretion in fifth days at most,59.33 mg/mL;extracellular protein secretion in fourth days up to 23.04mg/mL.