The detection of pathogens within food products plays a role of considerable importance for agri-food industries. The presence of harmful entities can lead to significant product waste and pollution, as well as economic losses. This thesis project is devoted to bacteriophages of the Lactococcus Lactis, pathogens that have a major impact on the dairy industry. Lactococcus Lactis belongs to the category of Bacteria of Lactic Acid. Lactic Acid (LAB), which are responsible for the lactose fermentation process necessary for the production of cheese, buttermilk, yogurt, etc. and to improve the of product preservation. The presence of bacteriophages causes the interruption of fermentation, and thus slowdowns in the production process as well as a deterioration in product quality. It is therefore important for industries ´ Constantly and effectively monitor production so as to be able to identify, isolate and sanitize contaminated batches so that the infection does not spread. The techniques currently used have high sensitivity and effectiveness, but they require long response times and have high costs. The purpose of this thesis work is the characterization of an electrochemical biosensor to detect the presence of Lactococcus lactis bacteriophages quickly and inexpensively; particularly focused on detecting the presence of these phages in samples containing milk, by varying the protocol for processing the sample, in order to provide the simplest sample analysis methodology possible. To analyze the presence of phages in the sample, the technique of Electrochemical Impedance Spectroscopy (EIS), which made it possible to observe the behavior on the sensor surface. Simultaneously, the following were performed absorbance measurements to monitor bacterial growth and verify its consistency with the electrochemically measured data. The first part of this thesis reports the measurements that allowed us to find the optimal treatment protocol to observe bacterial growth and their inhibition due to the presence of phages, while in the second part we approached a real case and, through the adoption of a simplified protocol, it was shown that the use of biosensors can make detections faster, while lowering costs. This project was carried out in collaboration with ARC - Centro Ricerche Applicate, Padova.
La rilevazione di agenti patogeni all’interno dei prodotti alimentari riveste un ruolo di notevole importanza per le industrie agroalimentari. La presenza di entità dannose può portare a rilevanti sprechi di prodotti ed inquinamento, oltre a perdite economiche. Questo progetto di tesi `e dedicato ai batteriofagi del Lactococcus Lactis, patogeni che hanno un forte impatto sull’industria lattiero-casearia. Il Lactococcus Lactis appartiene alla categoria dei Batteri dell’Acido Lattico (LAB), responsabili del processo di fermentazione del lattosio, necessario per la produzione di formaggi, latticello, yogurt, etc. e di migliorare i tempi di conservazione dei prodotti. La presenza di batteriofagi causa l’interruzione della fermentazione, e quindi rallentamenti nel processo di produzione oltre ad un peggioramento della qualità del prodotto. E quindi importante per le industrie ´ monitorare costantemente ed efficacemente la produzione in modo tale da riuscire ad identificare, isolare e sanificare i lotti contaminati, cos`ı che l’infezioni non si diffonda. Le tecniche al momento utilizzate hanno un’alta sensibilità ed efficacia, ma richiedono lunghi tempi di risposta ed hanno alti costi. Lo scopo di questo lavoro di tesi `e la caratterizzazione di un biosensore elettrochimico per rilevare la presenza di batteriofagi del Lactococcus Lactis in modo rapido ed economico; in particolar modo si `e focalizzata l’attenzione sul rilevare la presenza di questi fagi in campioni contenenti del latte, variando il protocollo di trattamento del campione, per fornire una metodologia di analisi dei campioni il più semplice possibile. Per analizzare la presenza di fagi nel campione si `e utilizzata la tecnica di Spettroscopia di Impedenza Elettrochimica (EIS), che ha permesso di osservare il comportamento sulla superficie del sensore. In simultanea sono state eseguite delle misure di assorbanza per monitorare la crescita batterica e verificarne la coerenza con i dati misurati elettrochimicamente. Nella prima parte della tesi sono riportate le misure che hanno permesso di trovare il protocollo di trattamento ottimale per osservare la crescita batterica e la loro inibizione a causa della presenza di fagi, mentre nella seconda parte ci si `e avvicinati ad un caso reale e, tramite l’adozione di un protocollo semplificato, si `e dimostrato che l’utilizzo dei biosensori può rendere le rilevazioni più rapide, abbattendo i costi. Questo progetto è stato svolto in collaborazione con ARC – Centro Ricerche Applicate, Padova
Rilevazione di batteriofagi del Lactococcus lactis in campioni di latte mediante biosensori elettrochimici
POGGI, SARA
2021/2022
Abstract
The detection of pathogens within food products plays a role of considerable importance for agri-food industries. The presence of harmful entities can lead to significant product waste and pollution, as well as economic losses. This thesis project is devoted to bacteriophages of the Lactococcus Lactis, pathogens that have a major impact on the dairy industry. Lactococcus Lactis belongs to the category of Bacteria of Lactic Acid. Lactic Acid (LAB), which are responsible for the lactose fermentation process necessary for the production of cheese, buttermilk, yogurt, etc. and to improve the of product preservation. The presence of bacteriophages causes the interruption of fermentation, and thus slowdowns in the production process as well as a deterioration in product quality. It is therefore important for industries ´ Constantly and effectively monitor production so as to be able to identify, isolate and sanitize contaminated batches so that the infection does not spread. The techniques currently used have high sensitivity and effectiveness, but they require long response times and have high costs. The purpose of this thesis work is the characterization of an electrochemical biosensor to detect the presence of Lactococcus lactis bacteriophages quickly and inexpensively; particularly focused on detecting the presence of these phages in samples containing milk, by varying the protocol for processing the sample, in order to provide the simplest sample analysis methodology possible. To analyze the presence of phages in the sample, the technique of Electrochemical Impedance Spectroscopy (EIS), which made it possible to observe the behavior on the sensor surface. Simultaneously, the following were performed absorbance measurements to monitor bacterial growth and verify its consistency with the electrochemically measured data. The first part of this thesis reports the measurements that allowed us to find the optimal treatment protocol to observe bacterial growth and their inhibition due to the presence of phages, while in the second part we approached a real case and, through the adoption of a simplified protocol, it was shown that the use of biosensors can make detections faster, while lowering costs. This project was carried out in collaboration with ARC - Centro Ricerche Applicate, Padova.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/36519