Antibacterial and Antibiofilm Activities of Crude Extract of Lasiodiplodia pseudotheobromae IBRL OS-64 against Foodborne Bacterium, Yersinia enterocolitica

The antibacterial and antibiofilm activities of crude extract of Lasiodiplodia pseudotheobromae IBRL OS-64 was studied and tested against a foodborne pathogenic bacterium, Yersinia enterocolitica. The ethyl acetate extract exhibited favorable antibacterial activity with the zone of inhibition was 20.3±0.6 mm compared to dichloromethane (15.0±0.3 mm) and butanol (9.0±0.3 mm) extracts. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values of the extract were 125 and 250 µg/mL, respectively. Structural degeneration studies through scanning electron microscopy (SEM) and transmission electron microscope (TEM) micrographs exhibited major abnormalities that occurred on the bacterial cells after exposure to the extract were complete alterations in their morphology and collapsed of the cells beyond repair. The findings showed that the extract possesses antibiofilm activity against the initial and preformed biofilm of Y. enterocolitica with the highest inhibition value of 69.12% and 58.70%, respectively. The results also revealed the initial biofilm was more susceptible to the extract as compared to pre-formed biofilm. The light microscopy (LM) and SEM photomicrographs proved that the fungal extract significantly eliminates extracellular polysaccharide (EPS) matrices and hinder the attachment of the bacterial cells for biofilm formation. Therefore, the current study suggested the ethyl acetate crude extract from an endophytic fungus, L. pseudotheobromae IBRL OS-64 may be an effective antibacterial and anti-biofilm agent to treat foodborne pathogens.

Polygalacturonase production by calcium alginate immobilized Enterobacter aerogenes NBO2 cells

Bacterial cells of Enterobacter aerogenes NBO2 were entrapped in calcium alginate beads in order to enhance polygalacturonase production compared to free cells. The optimized condition of 5 % (w/v) sodium alginate concentration, agitation speed of 250 rpm, and 15 beads of calcium alginate with inoculum size of 4 % (v/v; 5.4 × 10(7) cells/ml) produced 23.48 U/mL of polygalacturonase compared to free cells of 18.54 U/ml. There was about 26.6 % increment in polygalaturonase production. However, in this study, there was 296.6 % of increment in polygalacturonase production after improvement parameters compared to before improvement parameters of calcium alginate bead immobilization cells (5.92 U/ml). This research has indicated that optimized physical parameters of calcium alginate bead immobilization cells have significantly enhanced the production of polygalacturonase.

Antimicrobial effects of Caulerpa sertularioides extract on foodborne diarrhea-caused bacteria

AIM

Caulerpa (C.) sertularioides has many therapeutic uses in the practice of traditional medicine in Malaysia. Crude methanolic, diethyl ether extract, ethyl acetate extract and butanolic extract from C. sertularioides were subjected to antimicrobial screening including the three Gram-positive and three Gram-negative diarrhea-caused bacteria.

MATERIALS AND METHODS

The antimicrobial activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the bacteria was examined via time-kill assay. In addition to the bactericidal effects study, microscopic observations using Scanning electron microscopy (SEM) was done to determine the major alterations in the microstructure of Bacillus (B.) subtilis.

RESULTS

Ethyl acetate extract demonstrated antibacterial activity towards all the tested bacteria and produced inhibition zone ranging from ≤ 9 mm - ≥ 15 mm. However, all the tested bacteria were resistant to the butanolic extract treatment. B. subtilis growth curve in the presence of the crude methanol extract at MIC showed bacteriostatic. The main abnormalities found from these microscopic observations were morphology alteration of the bacteria cells after exposure to the methanol extract.

CONCLUSIONS

Data from this study revealed that C. sertularioides may be potential antimicrobial agents against foodborne Gram-positive and Gram-negative bacteria particularly cause diarrhea, and also food spoilage microorganisms.

Effects of Methanol Extract of Wedelia chinensis Osbeck (Asteraceae) Leaves against Pathogenic Bacteria with Emphasise on Bacillus cereus

The antibacterial activity of the methanol extract of Wedelia chinensis leave was studied and tested against three pathogenic Gram positive bacteria (Bacillus cereus, B. subtilis and Stapylococcus aureus) and three pathogenic Gram negative bacteria (Escherichia coli, Proteus rettgeri and Pseudomonas aeruginosa) by the disk diffusion assay and broth dilution methods. The extract exhibited favourable antibacterial activity against the bacterial cells but was more potent against Gram positive bacteria with the minimum inhibition concentration of 3.12 to 6.25 mg/ml compared to the Gram negative bacteria which had minimum inhibition concentration values of 25 mg/ml. The time-kill study suggested that the extract possessed bactericidal properties at higher concentrations and eradicated the growth of bacterial cells. The major abnormalities occurred to the bacterial cells after exposed to the extract were complete alterations in their morphology and collapsed of the cells beyond repair. The methanol extract of W. chinensis may be an effective antibacterial agent to treat bacterial infections.

In vitro and in situ antiyeast activity of Gracilaria changii methanol extract against Candida albicans

BACKGROUND AND OBJECTIVES

The Gracilaria (G.) sp are widely used in the traditional medicine in Malaysia. The methanol extract of Gracilaria changii B.M. Xia & I.A. Abbott (Gracilariaciae) was evaluated for antiyeast activity against Candida albicans (Berkhout).

MATERIALS AND METHODS

The antiyeast activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the yeast was also examined via time-kill assay. In addition, the in situ antiyeast activity was studied by microscopic observations using scanning electron microscopy (SEM), transmission electron microscopy (TEM) to determine the major alterations in the microstructure of Candida (C.) albicans.

RESULTS AND DISCUSSION

The extract showed a favourable antimicrobial activity against C albicans with a minimum inhibitory concentration (MIC) value of 1.56 mg/mL. The main abnormalities noted from the SEM and TEM studies were the internal shrinkage of cell, disorganization within the cell cytoplasm and complete collapse of the yeast cells after 36 h of exposure to the extract. The time-kill assay suggested that the G. changii extract significantly inhibited C. albicans growth and it also exhibited prolonged antiyeast activity against the C albicans.

CONCLUSION

The extract has shown in vitro fungicidal properties against C. albicans and should be investigated for its therapeutic potential.

Involvement of Physical Parameters in Medium Improvement for Tannase Production by Aspergillus niger FETL FT3 in Submerged Fermentation

Aspergillus niger FETL FT3, a local extracellular tannase producer strain that was isolated from one of dumping sites of tannin-rich barks of Rhizophora apiculata in Perak, Malaysia. This fungus was cultivated in 250 mL Erlenmeyer flask under submerged fermentation system. Various physical parameters were studied in order to maximize the tannase production. Maximal yield of tannase production, that is, 2.81 U per mL was obtained on the fourth day of cultivation when the submerged fermentation was carried out using liquid Czapek-Dox medium containing (percent; weight per volume) 0.25% NaNO₃, 0.1% KH₂PO₄, 0.05% MgSO₄ ·7H₂O, 0.05% KCl, and 1.0% tannic acid. The physical parameters used initial medium pH of 6.0, incubation temperature of 30°C, agitation speed of 200 rpm and inoculums size of 6 × 10⁶ spores/ ml. This research has showed that physical parameters were influenced the tannase production by the fungus with 156.4 percent increment.

Effects of Vernonia cinerea less methanol extract on growth and morphogenesis of Candida albicans

BACKGROUND AND OBJECTIVES

Vernonia (V.) cinerea Less (Asteraceae) have many therapeutic uses in the practice of traditional medicine. The methanol extract of V cinerea, was screened for antiyeast activity against pathogenic yeast Candida albicans.

MATERIALS AND METHODS

The antimicrobial activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the yeast was also examined via time-kill assay. In addition to the fungicidal effects study, microscopic observations using Scanning (SEM) electron microscopy, Transmission (TEM) electron microscopy and light microscopy (LM) were done to determine the major alterations in the microstructure of Candida (C) albicans.

RESULTS AND DISCUSSION

The extract showed a favorable antimicrobial activity against C. albicans with a minimum inhibitory concentration (MIC) value of 1.56 mg/mL. Time-kill assay suggested that Vernonia cinerea extract had completely inhibited Candida albicans growth and also exhibited prolonged antiyeast activity. The main abnormalities notes from these microscopic observations were the alterations in morphology and complete collapse of the yeast cells after 36 h of exposure to the extract.

CONCLUSION

The extract of Vernonia cinerea may be an effective agent to treat the Candida albicans infection.

Tannase enzyme production by entrapped cells of Aspergillus niger FETL FT3 in submerged culture system

The ability of immobilized cell cultures of Aspergillus niger FETL FT3 to produce extracellular tannase was investigated. The production of enzyme was increased by entrapping the fungus in scouring mesh cubes compared to free cells. Using optimized parameters of six scouring mesh cubes and inoculum size of 1 × 10(6) spores/mL, the tannase production of 3.98 U/mL was obtained from the immobilized cells compared to free cells (2.81 U/mL). It was about 41.64% increment. The immobilized cultures exhibited significant tannase production stability of two repeated runs.

Production and Optimization of Cellulase Enzyme Using Aspergillus niger USM AI 1 and Comparison with Trichoderma reesei via Solid State Fermentation System

Novel design solid state bioreactor, FERMSOSTAT, had been evaluated in cellulase production studies using local isolate Aspergillus niger USM AI 1 grown on sugarcane bagasse and palm kernel cake at 1 : 1 (w/w) ratio. Under optimised SSF conditions of 0.5 kg substrate; 70% (w/w) moisture content; 30°C; aeration at 4 L/h · g fermented substrate for 5 min and mixing at 0.5 rpm for 5 min, about 3.4 U/g of Filter paper activity (FPase) was obtained. At the same time, comparative studies of the enzymes production under the same SSF conditions indicated that FPase produced by A. niger USM AI 1 was about 35.3% higher compared to Trichoderma reesei. This shows that the performance of this newly designed SSF bioreactor is acceptable and potentially used as prototype for larger-scale bioreactor design.

Toxicity study of Vernonia cinerea

The methanol extract of Vernonia cinerea Less (Asteraceae), which exhibited antimicrobial activity, was tested for toxicity. In an acute toxicity study using mice, the median lethal dose (LD(50)) of the extract was greater than 2000 mg/kg, and we found no pathological changes in macroscopic examination by necropsy of mice treated with extract. As well as the oral acute toxicity study, the brine shrimp lethality test was also done. Brine shrimp test LC(50) values were 3.87 mg/mL (6 h) and 2.72 mg/mL (24 h), exhibiting no significant toxicity result. In conclusion, the methanol extract of V. cinerea did not produce toxic effects in mice and brine shrimp.

Antimicrobial Activity of Emilia sonchifolia DC., Tridax procumbens L. and Vernonia cinerea L. of Asteracea Family: Potential as Food Preservatives

Chemical preservatives have been used in the food industry for many years. However, with increased health concerns, consumers prefer additive-free products or food preservatives based on natural products. This study evaluated antimicrobial activities of extracts from Emilia sonchifolia L. (Common name: lilac tassel flower), Tridax procumbens L. (Common name: tridax daisy) and Vernonia cinerea L. (Common name: Sahadevi), belonging to the Asteracea family, to explore their potential for use against general food spoilage and human pathogens so that new food preservatives may be developed. Three methanol extracts of these plants were tested in vitro against 20 bacterial species, 3 yeast species, and 12 filamentous fungi by the agar diffusion and broth dilution methods. The V. cinerea extract was found to be most effective against all of the tested organisms and the methanol fraction showed the most significant (p < 0.05) antimicrobial activity among all the soluble fractions tested. The minimum inhibitory concentrations (MICs) of extracts determined by the broth dilution method ranged from 1.56 to 100.00mg/mL. The MIC of methanol fraction was the lowest in comparison to the other four extracts. The study findings indicate that bioactive natural products from these plants may be isolated for further testing as leads in the development of new pharmaceuticals in food preservation as well as natural plant-based medicine.

Enzymatic deinking of laser printed office waste papers: some governing parameters on deinking efficiency

The protocol for the enzymatic deinking of laser printed waste papers on a laboratory scale using cellulase (C) and hemicellulase (H) of Aspergillus niger (Amano) was developed as an effective method for paper recycling. A maximum deinking efficiency of almost 73% by the enzyme combination of C:H was obtained using the deinking conditions of pulping consistency of 1.0% (w/v) with the pulping time of 1.0min, temperature of 50 degrees C, pH=3.5, agitation rate of 60rpm, pulp concentration of 4% (w/v), concentration of each enzyme of 2.5U/g air dried pulp and the enzyme ratio of 1:1. The deinking efficiency was further enhanced to 95% using the optimized flotation system consisting of pH=6.0, Tween 80 of concentration 0.5% (w/w), working air flow rate of 10.0L/min and temperature of 45 degrees C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed.

Laboratory-scale production of lignin-degrading enzymes by free and entrapped cells ofPhanerochoete chrysosporium in a tubular air-lift bioreactor

The production of lignin-degrading enzymes by free and entrapped cells ofPhanerochoete chrysosporium in a tubular air-lift bioreactor was studied. Under optimized cultural conditions the production of lignin peroxidase by free cells, calcium-alginate-entrapped cells and scouring-mesh-entrapped cells was in a ratio of 520ratio720ratio950 mU/mL, while the production of manganese peroxidase was in a ratio of 350ratio480ratio620 mU/mL. The stability of the entrapped cells by fed-batch systems was highest after 3 feeding experiments which is similarly demonstrated in the repeated use of the preparations in batch system.