Initially, a new moderate halophilic strain was locally isolated from seawater. The partial 16S rRNA sequence analysis positioned the organism in Marinobacter genus and was named 'Marinobacter litoralis SW-45'. This study further demonstrates successful utilization of the halophilic M. litoralis SW-45 lipase (MLL) for butyl ester synthesis from crude palm fruit oil (CPO) and kernel oil (CPKO) in heptane and solvent-free system, respectively, using hydroesterification. Hydrolysis and esterification of enzymatic [Thermomyces lanuginosus lipase (TLL)] hydrolysis of CPO and CPKO to free fatty acids (FFA) followed by MLL-catalytic esterification of the concentrated FFAs with butanol (acyl acceptor) to synthesize butyl esters were performed. A one-factor-at-a-time technique (OFAT) was used to study the influence of physicochemical factors on the esterification reaction. Under optimal esterification conditions of 40 and 45 °C, 150 and 230 rpm, 50% (v/v) biocatalyst concentration, 1:1 and 5:1 butanol:FFA, 9% and 15% (w/v) NaCl, 60 and 15 min reaction time for CPO- and CPKO-derived FFA esterification system, maximum ester conversion of 62.2% and 69.1%, respectively, was attained. Gas chromatography (GC) analysis confirmed the products formed as butyl esters. These results showed halophilic lipase has promising potential to be used for biosynthesis of butyl esters in oleochemical industry.
A report on the de novo Whole Genome Sequence (WGS) of Marinobacter litoralis SW-45, a moderately salt-tolerant bacterium isolated from the seawater in Malaysia is presented. The strain has a genome size of 3.45 Mb and is capable of producing halophilic lipase, protease and esterase enzymes. Computational prediction of non-coding RNA (ncRNA) genes in M. litoralis SW-45 was performed using standalone software known as the non-coding RNA characterization (nocoRNAc). In addition, a phylogenetic tree showing the evolutionary relationship between the strain and other members of the genus Marinobacter was constructed using 16SrRNA sequence information. A total of 385 ncRNA transcripts, 1124 terminator region, and 2350 Stress Induced Duplex Destabilization sites were predicted. The current WGS shotgun project has provided the relevant genetic information that may be useful for the strain's improvement studies. This manuscript gives the first description of M. litoralis with a complete genome.
This study reports the biodiversity of thermophilic cellulolytic bacterial strains that present in the north Malaysian mangrove ecosystem. Soil samples were collected at the four most northern state of Malaysia (Perak, Pulau Pinang, Kedah and Perlis). The samples obtained were first enriched in nutrient broth at 45°C and 55°C prior culturing in the carboxymethylcellulose (CMC) agar medium. Repeated streaking was performed on the CMC agar to obtain a pure culture of each isolate prior subjecting it to hydrolysis capacity testing. The isolates that showing the cellulolytic zone (halozone) were sent for 16S rRNA sequencing. Total seven isolates (two from Perak, three from Kedah, another two were from Perlis and Penang each) showed halozone. The isolate (KFX-40) from Kedah exhibited highest halozone of 3.42 ± 0.58, meanwhile, the one obtained from Perak (AFZ-0) showed the lowest hydrolysis capacity (2.61 ± 0.10). Based on 16S rRNA sequencing results, 5 isolates (AFY-40, AFZ-0, KFX-40, RFY-20, and PFX-40) were determined to be Anoxybacillus sp. The other two isolates were identified as Bacillus subtilis (KFY-40) and Paenibacillus dendritiformis (KFX-0). Based on growth curve, doubling time of Anoxybacillus sp. UniMAP-KB06 was calculated to be 32.3 min. Optimal cellulose hydrolysis temperature and pH of this strain were determined to be 55°C and 6.0 respectively. Addition of Mg2+ and Ca2+ were found to enhance the cellulase activity while Fe3+ acted as an enzyme inhibitor.
This work evaluates the fungicidal effect of essential oil from Coleus aromaticus (C. aromaticus) by solvent-free microwave-assisted extraction with a yield of 0.54%. Fourier-transform infrared spectroscopy was utilised to identify the functional groups, which were O-H, C-O, C-H, and C=C. Gas chromatography-mass spectrometry analysis was performed to determine the primary essential oil components, namely, thymol (92.62%), thymoquinone (2.64%), creosol (1.77%), linalool (1.68%), p-Cymene-2,5-diol (0.73%), and p-Cymene (0.56%). The inhibitory effect of essential oil extracted from C. aromaticus against the isolated fungi, Aspergillus niger from mango, was investigated. The mycelial growth inhibition of the extracted essential oil by the poisoned food test and disc diffusion assay showed the reduction at 79.63 ± 1.7 and 70.45 ± 6.54%, respectively. In vivo experiment was conducted with artificially wounded and unwounded mangoes, applying the extracted essential oil to the wounded mangoes inoculated with A. niger that could decrease the disease incidence from 100 to 58.33 ± 14.43%. Meanwhile, the treatment of the extracted essential oil did not affect the quality of the mango and it also shows improvement in weight loss reduction of the mango in comparison to the chemical fungicide and untreated mango. Hence, essential oil from C. aromaticus by solvent-free microwave-assisted extraction could be used as an effective control for the fruit spoilage and potential source of fruit preservative.
Mango has a high global demand. Fruit fungal disease causes post-harvest mango and fruit losses. Conventional chemical fungicides and plastic prevent fungal diseases but they are hazardous to humans and the environment. Direct application of essential oil for post-harvest fruit control is not a cost-effective approach. The current work offers an eco-friendly alternative to controlling the post-harvest disease of fruit using a film amalgamated with oil derived from Melaleuca alternifolia. Further, this research also aimed to assess the mechanical, antioxidant, and antifungal properties of the film infused with essential oil. ASTM D882 was performed to determine the tensile strength of the film. The antioxidant reaction of the film was assessed using the DPPH assay. In vitro and in vivo tests were used to evaluate the inhibitory development of the film against pathogenic fungi, by comparing the film with different levels of essential oil together with the treatment of the control and chemical fungicide. Disk diffusion was used to evaluate mycelial growth inhibition, where the film incorporated with 1.2 wt% essential oil yielded the best results. For in vivo testing of wounded mango, the disease incidence was successfully reduced. For in vivo testing of unwounded mango to which the film incorporated with essential oil was applied, although some quality parameters such as the color index were not significantly affected, weight loss was reduced, soluble solid content was increased, and firmness was increased, compared to the control. Thus, the film incorporated with essential oil (EO) from M. alternifolia can be an environmentally friendly alternative to the conventional approach and the direct application of essential oil to control post-harvest disease in mango.