Identification and biological control of microbial rotting agents of stored beets in sugar industry

Abstract

There is a long period distance between sugar beet harvest and its transport to sugar factory. Sugar beet crop is damaged and injured during harvest and transport which provides a suitable place for various saccharolytic microorganism growths in terms of temperature, moisture, pH and glucose concentration. In this study, samples were randomly selected from root stored in spring 2010 and also the processed syrup in one of the sugar factories in Isfahan, in order to isolate and identify microorganisms. After washing and disinfecting root surface, infected pieces were taken from different regions of the tissue, were washed, and microorganisms were isolated and identified using standard microbiological methods. Different types of gram-positive bacilli and cocci, including Bacillus, Leuconostoc, Staphylococcus, and Streptococcus from bacteria, and several types of fungi including Paecilomyces, Chrysosporium, Pencillium, Fusarium and Pythium were isolated and were purified. Pathogenic bacteria such as Staphylococcus aureus and Staphylococcus saprophyticus were detected among isolated bacteria. Bacterial counting in syrup collected after heat processing showed the presence of bacterial spores and the growth of bacteria as 53 colony forming unit per milliliter after vegetation. The bacterial population which remained in processed syrup was Bacillus species. These bacteria are called as ‘opportunistic pathogens’ and some of them produce allergens. Therefore, it is important to control their population in stored sugar beet which can affect the quality of health parameters. Ethanol extract from bee Propolis had significant effect on isolated microorganisms. The minimum lethal concentration of Propolis was 6 times less than sodium hypochlorite and 12 times less than calcium hypochlorite.

Keywords

• bee propolis
• calcium hypochlorite
• microbial counting
• sodium hypochlorite
• sugar beet
• storing