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

There is a long period between harvested beets and their transfer to the sugar factory. Sugar beet crop is damaged and injured during harvest and transport which provides a suitable place for various saccharoliytic microorganisms growth in terms of temperature, moisture, pH and glucose concentration. In this study, samples were randomly selected from the roots stored in spring 2010 and also the processed syrup in one of the sugar factories in Isfahan, to isolate and identify microorganisms. After washing and disinfecting the root’s surface, infected pieces were taken from different parts of tissue. After preparation of dilution series, isolation and identification of microorganisms were carried out using standard microbiological methods. In the next stage, the impact of the ethanolic extract of the honey bee prepolis as an antimicrobial agent was studied under the controlled environment on the isolated bacteria and fungi. And, its effect was compared with two disinfecting materials, i.e. sodium hypochlorite and calcium hypochlorite. Different kinds of gram-positive bacilli and cocci, including genus Bacillus, Leuconostoc, Staphylococcus and Streptococcus from bacteria, and several types of fungi constitute Paecilomyces, Chrysosporium, Pencillium, Fusarium and Pythiumwere isolated, purified and identified. Pathogenic bacteria such as Staphylococcus aureus and Staphylococcus saprophyticus were detected among the isolated bacteria. Bacterial counting in heated syrup showed the presence of bacterial spores and the re- growth of bacteria as 53 colony forming units per ml. after emergence. The bacterial population remained in heated syrup was belonged to the Bacillus species. These bacteria are called as ‘ human opportunistic pathogens’ and some of them are allergens. Therefore, it is important to control their population instored sugar beet which can improve the quality of the crop and health parameters. Ethanol extract from bee Propolis had significant effect on isolated microorganisms, so that the minimum lethal concentration of Propolis was 6 times less than sodium hypochlorite and 12 times less than calcium hypochlorite.