Date of Award

2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Dr. Gadelhak Gaber

Second Advisor

Dr. Giles Hardy

Third Advisor

Dr. Ali H. Khalil

Comments

Several actinomycetes species were isolated from UAE soil using conventional microbiological techniques. Out of thirty-eight isolates, only three (one streptomycete actinomycete and two non-streptomycete actinomycetes which were isolated by the actinophages technique) were selected based on their high production of the chitinase enzyme. The three isolates were identified to the species level using cultural, physiological, biochemical and chemotaxonomical characteristics. Isolates 1, 7 and 40 were identified as Actinoplanes philippinensis, Actinoplanes missouriensis and Streptomyces clavuligerus, respectively.

Chitinolytic activity of the three isolates were tested against Drosophila melanogaster development as percentage of successful pupal formation. The three actinomycetes were applied individually against Drosophila melanogaster, then in pair wise combinations and then all together to study the synergistic and antagonistic effects between them on pupal formation.

The application of either Actinoplanes philippinensis or Actinoplanes missouriensis gave a good effect, shown as lowest pupal formation percentages, these were 39.43 ± 2.06% and 31.75 ± 3.79%, respectively. Whilst, Streptomyces clavuligerus was the least effective being, 55.71 ± 5.56% compared to control treatment.

Streptomyces clavuligerus which gave the least activity when applied individually, was synergized in the presence of Actinoplanes philippinensis (27.35 ± 3.95%) and Actinoplanes missouriensis (33.24 ± 2.97%). Meanwhile, an antagonistic effect was observed when Actinoplanes philippinensis and Actinoplanes missouriensis were combined. This antagonism resulted in a high percentage (51.06 ± 5.15%) of successful pupal formation. When all three isolates were combined no antagonism (37.47 ± 2.48%) was observed compared to when the isolates were used alone.

The Actinoplanes philippinensis and missouriensis (isolate 1 and 7, respectively) were compared with their standards using the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) to detect the genetic similarities and dissimilarities of DNA using six random primers. The study found that a total number of 43 scored bands for isolate 1 and its standard, only 18 of them were polymorphic comprising 42% and 25 were monomorphic being 58%. As for isolate 7 and its standard, there were a total number of 11 scored bands. Eight (72.7%) of them were polymorphic while only three (27.3%) were monomorphic.

This work for the first time indicates the potential of screening actinomycetes as biocontrol agents against important insect pests of agricultural crops in the United Arab Emirates or elsewhere.

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