Farinazleen Mohamad Ghazali

Production of bacterial endoglucanase from pretreated oil palm empty fruit bunch by bacillus pumilus EB3

In this study, endoglucanase was produced from oil palm empty fruit bunch (OPEFB) by a locally isolated aerobic bacterium, Bacillus pumilus EB3. The effects of the fermentation parameters such as initial pH, temperature, and nitrogen source on the endoglucanase production were studied using carboxymethyl cellulose (CMC) as the carbon source. Endoglucanase from B. pumilus EB3 was maximally secreted at 37 degrees C, initial pH 7.0 with 10 g/l of CMC as carbon source, and 2 g/l of yeast extract as organic nitrogen source. The activity recorded during the fermentation was 0.076 U/ml. The productivity of the enzyme increased twofold when 2 g/l of yeast extract was used as the organic nitrogen supplement as compared to the non-supplemented medium. An interesting finding from this study is that pretreated OPEFB medium showed comparable results to CMC medium in terms of enzyme production with an activity of 0.063 U/ml. As OPEFB is an abundant solid waste at palm oil mills, it has the potential of acting as a substrate in cellulase production.

Multiplex PCR for the concurrent detection and differentiation of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium

Salmonellosis outbreaks involving typhoid fever and human gastroenteritis are important diseases in tropical countries where hygienic conditions are often not maintained. A rapid and sensitive method to detect Salmonella spp., Salmonella Typhi and Salmonella Typhimurium is needed to improve control and surveillance of typhoid fever and Salmonella gastroenteritis. Our objective was the concurrent detection and differentiation of these food-borne pathogens using a multiplex PCR. We therefore designed and optimized a multiplex PCR using three specific PCR primer pairs for the simultaneous detection of these pathogens. The concentration of each of the primer pairs, magnesium chloride concentration, and primer annealing temperature were optimized before verification of the specificity of the primer pairs. The target genes produced amplicons at 429 bp, 300 bp and 620 bp which were shown to be 100% specific to each target bacterium, Salmonella spp., Salmonella Typhi and Salmonella Typhimurium, respectively.

Production system and harvesting stage influence on nitrate content and quality of butterhead lettuce

Leafy vegetables such as lettuce grown under different production systems may accumulate different concentrations of nitrate which may reach to the levels potentially toxic to humans. Moreover, nitrate accumulation varies in various plant parts and physiological age of the plant. Therefore, to determine the effect of production system and harvesting stage on nitrate accumulation and quality of butterhead lettuce, a study was conducted considering two lettuce production systems namely hydroponic and organic, and four different harvesting stages such as 35, 38, 41 and 44 days after transplanting (DAT). The experimental design was complete randomized design (CRD) with four replications. Hydroponic and organic systems performed similar in terms of yield, quality and nitrate content of butterhead lettuce. Delaying harvesting can not only increase yield but also can minimize nitrate accumulation and health hazard risk as well. Delay in harvesting stage may result in quality deterioration of lettuce and increased production cost. Thus, a compromise is necessary to consider 41 DAT as the optimum stage to harvest butterhead lettuce with significantly higher reduction of nitrate content in both outer adult leaf blades and young leaves of hydroponic lettuce. Fresh weight, firmness and color of butterhead lettuce at this stage were still acceptable.

Characterisation of L. monocytogenes strains isolated from salad vegetables

Seventy-one strains of L. monocytogenes isolated from raw salad vegetables consumed in the minimally processed state in Malaysia were characterised by serotyping, random amplified polymorphic DNA-polymerase chain reaction analysis (RAPD-PCR) and antimicrobial susceptibility testing. Based on serotyping, only one strain belonged to serotype 4 while the rest were from serotype 1. RAPD-PCR typing was carried out using two primers, i.e., OPAR-8 and GEN 1-50-09. Based on RAPD-PCR fingerprinting, the strains could be grouped into six composite profile groups and a solitary isolate. The isolates were also evaluated against 16 antibiotics. Excluding nalidixic acid and oxacillin for which L. monocytogenes has natural resistance, the highest prevalence of resistance was against cephalexin. None of the isolates were resistant against imipenem and kanamycin. The multiple antibiotic resistance index (MARI) ranged from 0.06 to 0.63. It was found that most (82%) isolates were susceptible to antibiotics commonly used in veterinary and human listeriosis treatment.