Bacterial adhesion to host cells is the most important probiotic character. However, the adhesion of probiotic should not
affect the viability of the host cells. In this study, Lactobacillus plantarum strain L8, Lactobacillus plantarum strain L20
and Lactobacillus pentosus strain S1 were tested for their cytotoxic effects through MTT assay and their ability to adhere
and colonize on HT-29 and CCD-18Co intestinal cells as detected microscopically using light microscopy and Scanning
Electron Microscopy (SEM). No cytotoxicity effects were observed on both intestinal cells following 24 h treatment with
all Lactobacillus strains. Additionally, all strains demonstrated strong adhesive activity where more than 100 bacteria
adhered to both intestinal cells although differences in the adhesion scores observed among different strains. The adhesion
as observed via SEM showed an autoagreggative pattern and adhered as clusters on the surface of both intestinal cells.
In conclusion, all three Lactobacillus strains are non-cytotoxic to both cells with strong adhesion ability on intestinal
cells and this study also proved that Malaysian fermented fish are good source of probiotic bacteria.
Recently researchers are interested with the biotherapeutic potential of probiotics in gut disease
treatment. The bacteria are generally regarded as a safe, have a stability of usage and originate
from the natural resources. The study aims to identify and characterize the potential probiotic
Lactic Acid Bacteria (LAB) isolated from Malaysian fermented fish product known as
Pekasam. Fourty isolates obtained were firstly screened for their antagonism activities against
the common pathogenic bacteria; Esherichia coli, Staphylococcus aureus and Klebsiella sp.
Our study revealed only three (labeled as L8, L20 and S1) of the isolates tested showed broad
antimicrobial effects towards the pathogenic bacteria. All of the isolates were also γ-hemolytic
and tolerant to various pH (pH 3, 5 and 7.5) and 0.3% (w/v) bile salts. The bacteria isolates
of strain L8 and L20 were susceptible to seven antibiotics tested except vancomycin and
tetracycline whereas S1 was resistant to all antibiotics. Phenotypic tests revealed that both
bacteria isolates of strain L8 and L20 were Bacillus megaterium while S1 was Pediococcus
pentosaceus whereas 16S rRNA gene sequence analysis showed potential bacteria isolates
of strain L8 and L20 belonged to the Lactobacillus plantarum (99% similarity) and S1 was
characterized as Lactobacillus pentosus (100% similarity) respectively. Our present study
showed that the probiotics of strain L8, L20 and S1 isolated from the fermented fish (Pekasam)
exhibited the potential probiotic properties to be developed as biotherapeutic agents.
Crude methanol extracts of a marine sponge, Aaptos aaptos, collected from three different localities namely Kapas, Perhentian and Redang Islands, Terengganu, Malaysia, were tested in vitro on a pathogenic Acanthamoeba castellanii (IMR isolate) to examine their anti-amoebic potential. The examination of anti-Acanthamoebic activity of the extracts was conducted in 24 well plates for 72 h at 30 °C. All extracts possessed anti-amoebic activity with their IC(50) values ranging from 0.615 to 0.876 mg/mL. The effect of the methanol extracts on the surface morphology of A. castellanii was analysed under scanning electron microscopy. The ability of the extracts to disrupt the amoeba cell membrane was indicated by extensive cell's blebbing, changes in the surface morphology, reduced in cell size and with cystic appearance of extract-treated Acanthamoeba. Number of acanthapodia and food cup was also reduced in this Acanthamoeba. Morphological criteria of apoptosis in Acanthamoeba following treatment with the sponge's extracts was determined by acridine orange-propidium iodide staining and observed by fluorescence microscopy. By this technique, apoptotic and necrotic cells can be visualized and quantified. The genotoxic potential of the methanol extracts was performed by the alkaline comet assay. All methanol extracts used were significantly induced DNA damage compared to untreated Acanthamoeba by having high percentage of scores 1, 2, and 3 of the DNA damage. Results from cytotoxicity and genotoxicity studies carried out in the present study suggest that all methanol extracts of A. aaptos have anti-amoebic properties against A. castellanii.