Screening for biotechnological applications from obligate halophilic fungi isolated from a man-made solar saltern in Thailand | |
| Author | Ali, Imran |
| Call Number | AIT Diss. no.FB-13-02 |
| Subject(s) | Microbial biotechnology Halophilic microorganisms |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. FB-13-02 |
| Abstract | Soil analyses from four man- made solar salterns located in Ban Laem district of Phetchaburi province in Thailand were carried out . Soil analysis of the sample revealed high salinity and moisture content, slight alkalinity and low amounts of nitrogen, total organic carbon and organic matter in the habitat. The site showing the most extreme conditions in terms of salinity was selected for further study . A total of 17 species from 43 isolates of microorganisms were obtained through serial dilutions of soil sam ples. The number of fungal isolates was found to be lower than the diversity in which they exist in non extreme environments. All isolates were morphologically studied and molecular identification and phylogenetic analysis were carried out for the obligate halophilic fungi. Six halophilic fungi were found in the isolates and were found to belong to 4 species. There were 5 strains of Aspergillus genus, namely Aspergillus flavus , Aspergillus gracilis , Aspergillus penicillioides (2 strains) and Aspergillus restrictus . One species was found to be yeast, namely, Sterigmatomyces halophiles , which was the most frequent isolate found among the halophilic fungi. All other isolates were found to be halotolerant fungi. Initial growth study of the halophilic fungi was c arried out to understand their growth characteristics and the length of the specific growth phases. All halophilic fungi showed the highest growth after 13- 15 days. Characterization of halophilic fungal isolates showed they were most adapted to 10 -15% Na Cl (w/v) and slight alkalinity (pH 7.0- 7.5) of the medium and temperature in the range of 30- 35 o C. Antibacterial, antioxidant and enzymatic activity were determined for each of the strains. All of the isolates in this study were found to have at least on e of the characteristics analyzed. Aspergillus flavus , Aspergillus gracilis and Aspergillus penicillioides (1) were found to produce metabolites which have high antibacterial potential. Aspergillus flavus and Aspergillus penicillioides (2) showed the highest antioxidant activity while Aspergillus gracilis and Aspergillus restrictus were found to be most promising candidates for enzymes (of the five enzymes tested) having good activity even under saline conditions. Crude xylanase from Aspergillus penicillioides (1) was selected for further studies because of the high quantities produced. Crude xylanase characterization from Aspergillus penicillioides (1) showed a polyextremophilic behavior showing the optimum enzyme activity at pH 5, 80 o C and 30% of salinity (w/v). The enzymes from these sources have many potential applications as they are able to catalyze reactions under some extreme conditions. |
| Year | 2013 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. FB-13-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| 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;Anal, Anil Kumar;Thammarat Koottatep |
| Scholarship Donor(s) | University of Balochistan, Quetta, Pakistan;AIT Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2013 |