A study on the production and use of thermotolerant probiotics for shrimp feeds | |
| Author | Bussarin Kosin |
| Call Number | AIT Diss. no.FB-11-04 |
| Subject(s) | Probiotics Animal nutrition Feeds--Analysis |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Engineering and Bioprocess Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. FB-11-04 |
| Abstract | Thermotolerant probiotic feeds that will have sufficient number of viable cells (usual acceptable values is 106 CFU/g) on extended storage at the point of application into commercial shrimp ponds. Thermotolerant lactic acid bacteria and Bacillus sp. preliminarily identified as Lactobacillus plantarum ssp.1 (ID lL), Leuconostoc mesenteroides ssp. mesenteroides/dextranicum2 (ID2L), Bacillus licheniformis (ID3B) and Bacillus subtilis (ID4B) were isolated under high temperature, bile salt and acid condition from healthy white shrimp (Penaeus vannamei) grown in natural farms and research ponds in Thailand. All of them found to exhibit proteolytic activity. These organisms and a . selected allochthonous (external source) L. brevis 860, screened from local fermented vegetable showed antagonistic effect on Vibrio sp. and some specific indicator food pathogens tested. For the selection criteria which indicate good adhesion on host surface which attribute to a competitive inhibition against host pathogen, they showed significant autoaggregation capacity compared to indicator pathogens where lactobacilli was found to be higher than bacilli. ID lL showed highest hydrophobic percentage. In coaggregation test, lactobacilli showed wide range of high coaggregation ability for most pathogens where ID3B showed highest percentage with aquatic pathogens and showed particular strong interactions with certain pathogens only. They were then studied for their heat tolerance. Autochthonous and allochthonous lactic acid bacteria (L. plantarum sspl (IDlL) and L.brevis 860) were selected for further study on their heat adaptation characteristics. Induction to heat tolerance was studied under different condition of pH, physiological growth state, temperature and time of heat pre-/treatment and growth media. Cultures at pH 7 and in stationary growth phase when exposed to heat adaptation temperature profile (preheated at 45°C, 20 min) were found to have improved decimal reduction time (D70 value) and survived better than those suspended at pH 3 and in log growth phase. In order to retain 50% cell survival, it was seen that L. plantarum sspl (IDlL) could be preheated to 50°C for a maximum of 15 min and L. brevis 860 to 45°C for a maximum of 15 to 20 min. Cross protection (another method of adaptation under osmotic conditions) by treating with 0.3M NaCl for 30 mins also led to good cell !ecovery. Preheated and cross protected L. plantarum sspl (IDlL) and L. brevis 860 were then manually sprayed (top-dressed) on hot white shrimp pellets collected at the outlet of a commercial pellet mill at 95°C and after it had cooled to 60°C and 50°C respectively. They were then stored in a refrigerator for 4 weeks. L. plantarum sspl (IDlL) grown in MRS with cross protection showed the highest survival percentage (47.8%) while L. brevis 860 had the highest survival of 41.7% for those grown on skimmed milk media. Similar tests were also conducted with heat tolerant mesophilic Bacillus sp., B. licheniformis (ID3B) and B.subtilis (ID4B) without heat adaptation. Each strains was sprayed (top-dressed) onto fresh feed pellet at temperatures of 80 and 70°C respectively. While the initial cell count was lower for those sprayed at high temperatures, the cell count was found to decrease rapidly after 4-weeks of refrigerated storage in the case of those sprayed at ambient temperature. Spraying probiotics at high temperature is recommended as it prevents the growth of fungi on the pellets which is a problem for feed storage. Overall, selected species with all probiotic characteristics and heat adaption capacity were obtained. They were applied to pellets in a commercial feed mill and were found to have sufficient viability after extended storage. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. FB-11-04 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Rakshit, Sudip Kumar |
| Examination Committee(s) | Athapol Noomhorm;Yakupitiyage, Amararatne;Anal, Anil Kumar;Little, David C. |
| Scholarship Donor(s) | Royal Thai Government Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2011 |