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Articles by Jacob H. Jacob
Total Records ( 5 ) for Jacob H. Jacob
  Fawzi I. Irshaid , Jacob H. Jacob , Yaseen A. Al-Soud and Hamdoon A. Mohammed
  Background and Objective: Pine wood nematode, Bursaphelenchus xylophilus, infects pine trees and causes the pine wilt disease. This disease is one of the major threats to pine trees, thus causing global concern. The present study aimed to evaluate the potential nematocidal effect of some 1,2,4-triazole derivatives and to analyze their structure-activity relationships. Materials and Methods: Eight previously synthesized 1,2,4-triazole derivatives were selected for this study and designated as compounds 1 through 8. The nematocidal effects of 6 different concentrations (50, 100, 200, 300, 400 and 500 μM) of these compounds were tested against Bursaphelenchus xylophilus. Results: At concentrations of 50-500 μM and with 6 h of exposure, the all of the test compounds killed nematodes in a concentration-dependent manner. Among these compounds, compound 1 exhibited the most potent nematocidal activity at all tested concentrations and exhibited the lowest LD50. The highest mortality rate of 100% was only observed by compound 1, followed by compound 2 with 85% mortality rate after exposure to 500 μM for 6 h. Under the same conditions, the lowest mortality rate of 33% was obtained by compound 4. The LD50 of 50 μM was recorded for compound 1, followed by compound 2 with 70 μM. The LD50 value of compound 4 was at least 10 times higher than that of compound 1. Analysis of their structure-activity relationships suggested that the highest nematocidal activity was due to the presence of a primary amine on the substituted phenyl ring. Conclusion: Monosubstituted forms of the phenyl ring displayed much better nematocidal activity compared to unsubstituted or di-substituted forms. Compound 1 showed the highest nematocidal activity of all tested compounds, a finding that corresponded to the presence of a primary amine on the phenyl ring. These results demonstrated for the first time, that compounds containing a 1,2,4-triazole ring could be of importance as nematocidal drugs for combatting the pine wilt disease, the potency of which is influenced by the specific substitution pattern on the phenyl ring.
  Khalaf Alhussaen , Emad I. Hussein , Khalid M. Al-Batayneh , Mahmoud Al-Khatib , Wesam Al Khateeb , Jacob H. Jacob , Mohamad A. Shatnawi , Ashraf Khashroum and Mohamed I. Hegazy
  Garlic extract is well known for its antibacterial and antifungal activity and is used to treat several plant pathogens. Pythium sp. was isolated from infected tomato seedlings grown in Jordan Valley (Jordan) and the species was identified as Pythium ultimum using morphological and molecular methods. The fungicidal activity of garlic extract with different concentrations in controlling the growth of the isolated Pythium sp. was determined in vitro. The control activity was highly dependent on Garlic extract concentration. For instance, undiluted garlic extract showed the highest control activity with no growth as compared to the biotic control without the extract whereas diluted garlic extracts 10 and 5% reduced the fungal growth to 15.5 and 41%, respectively. The results of this study show that garlic extract could successfully control Pythium ultimum on tomato seedlings and is considered as an environmentally friendly product.
  Fawzi I. Irshaid and Jacob H. Jacob
  Xylene is frequently released into the environment from biomass. As a consequence of this, its bioaccumulation can cause adverse health effects in humans. The purpose of this study was to screen for aerobic xylene-degrading bacteria from gasoline contaminated soil sites located around gas stations in the city of Al-Mafraq, Jordan. The effects of some physicochemical factors were examined. The 10 g of soil sample were transferred to Stanier’s mineral medium supplemented with 1% m-xylene and incubated at 30°C for 72 h. At least 4 aerobic m-xylene degrading isolates, designated as X1-X4 were identified using biochemical and molecular biology techniques. Isolates X1 and X2 were rod-shape Gram negative, oxidase and catalase positive bacteria. Isolate X3 was a rod-shape and Gram negative bacterium that was catalase positive and oxidase negative. Isolate X4 was a rod-shape, spore forming and Gram positive bacterium that was oxidase and catalase positive. Isolates X1, X2 and X4 showed high similarity to Pseudomonas aeruginosa, Pseudomonas stutzeri and Bacillus firmus, respectively, whereas X3 was a novel species of the genus Citrobacter, similar to Citrobacter amalonaticus. The growth rates of these isolates were slower at 2% m-xylene than at 1% m-xylene. The growth rate was less when the temperature was reduced from 30-25°C, whereas, at 45°C, the growth rate almost completely ceased. The growth rate was higher at pH 6.5 than at pH 5.5 or 8.5. The shortest generation times were found to be 8 h for Bacillus firmus, followed by 9 h for Pseudomonas stutzeri, 10 h for Citrobacter amalonaticus and 11 h for Pseudomonas aeruginosa under 1% m-xylene at 30°C and pH 6.8. In conclusion, we reported for the first time the isolation of four bacterial species with the ability to utilize m-xylene as a growth substrate.
  Fawzi I. Irshaid , Khalid A. Tarawneh , Jacob H. Jacob and Aisha M. Alshdefat
  This study was performed to assess the antioxidant and antibacterial properties of methanolic extracts derived from aerial parts of four Jordanian medicinal plants (Artemisia sieberi, Peganum harmala, Rosmarinus officinalis (Green-Flowered) and Sarcopterium spinosium). The possible relationship between these biological properties and the total phenolic concentrations of these extracts were also be determined. The antioxidant capacity and total phenolic concentrations were assessed by the ABTS method and Folin- Ciocalteu method, respectively. The amount of the extract required to scavenge 50% of ABTS (IC50) was also measured. Broth dilution and disc diffusion assays were performed to measure the antibacterial activity of these extracts against available bacterial strains. Variations were observed among the examined plants in antioxidant and antibacterial activities as well as in their phenol contents. According to ABTS assay and IC50 value, the highest free radical scavenging potential was found in Sarcopterium spinosium, followed by Rosmarinus officinalis, Peganum harmala and Artemisia sieberi, respectively. Similarly, the results of antibacterial assays showed that Sarcopterium spinosium exhibited the highest antibacterial activity against all tested bacterial strains as compared to Rosmarinus officinalis, Peganum harmala and Artemisia sieberi. Moreover, Sarcopterium spinosium contained the highest amount of phenolic compounds followed by, Rosmarinus officinalis, Artemisia sieberi and Peganum harmala, respectively. In conclusion, these plants are not only interesting sources for antimicrobial agents but also have a considerable amount of antioxidants. In addition, these findings revealed that the antioxidant capacity and antibacterial activity of these plant extracts do not necessary be attributed to their total phenolic concentrations.
  Jacob H. Jacob and Fawzi I. Irshaid
  A strain of Citrobacter was isolated from the hypersaline Dead Sea of Jordan. The strain (DS1) was identified by molecular and biochemical methods. Based on 16S rRNA gene analysis, the isolate is most related to Citrobacter freundii and Citrobacter murliniae (maximum similarity is 94%). Relative to other citrobacters, the strain has a relatively high GC content (55%). The biochemical tests showed that the strain is Gram-negative, oxidase-negative and ferment lactose as other enteric bacteria. DS1 utilizes citrate as sole carbon source as other citrobacters. However, the main differences between our strain and other citrobacters is that the isolate is mild halophilic (optimum NaCl concentration in the growth medium is 4%) and o-nitrophenyl-β-galactosidase (ONPG)-negative. Based on the differences in the physiological and biochemical properties, as well as low 16S rRNA sequence similarity of this novel isolate, DS1 is suggested as new species of Citrobacter in the family Enterobacteriaceae.
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