Nanotechnology is the study and advanced/modern application of small object that can be practised across various scientific fields, such as physics, chemistry, biology, material science, engineering, etc. It has been widely applied in the 21st century, and it also paved the way to the green approach in technology in the form of green nanotechnology. The field of nanotechnology enables silver nanoparticles (AgNPs) to be widely used as novel therapeutic agents in the semblance of antibacterial, antifungal, antiviral, anti-inflammatory, and anti-cancerous agents. In this study, plant extract of Polygonum minus (known as kesum) was used for the synthesis of AgNPs from silver nitrate (AgNO3) solution. The green synthesis, which is an alternative way to produce silver nanoparticles, was proposed because it is cost-effective and environmentally friendly. The colourless reaction mixture was observed to slowly change from yellowish-green to reddish-brown, indicating the reduction of silver ion after several minutes of reaction. The AgNPs were characterised by Ultraviolet-visible (UV-Vis) spectrophotometer, Field-emission Scanning Electron Microscope (FE-SEM), and Energy-Dispersive X-Ray Spectroscopy (EDX). The results obtained from the UV-Vis spectrophotometer showed a sharp peak absorbance at 440 nm, which indicated the reduction of Ag+ to metallic Ag. Meanwhile, the size of AgNPs observed via FE-SEM was in the range of 15–25 nm. Accordingly, based on the EDX analysis, 82.6% of AgNPs were determined to show strong peaks for silver (Ag). Three bacteria, i.e. Staphylococcus aureus (ATCC 43300), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 15442) were chosen to be tested in this study. The morphological changes of bacterial cells treated with AgNPs were observed by FE-SEM, showing that the AgNPs have excellent antimicrobial properties against microorganisms. Thus, the ability of AgNPs to release Ag ions is a critical factor in its antimicrobial activity.
Protein function depends greatly on its structure. Based on this principle, it is vital to study the
protein structure in order to understand its function. This study attempts to build the predicted
model of lipase gene in Rhodococcus sp. NAM81 using homology modelling method. The
predicted structure was then used to investigate the function of protein through several
bioinformatic tools. The DNA sequence of lipase gene was obtained from the Rhodococcus sp.
NAM81 genome scaffold. Blastx analysis showed 100% identity to the target enzyme andthe
appropriate template for homology modelling was determined using Blastp analysis. The 3D
protein structure was built using two homology modelling software, EsyPred3D and Swiss
Model Server. Both structures built obtained LGScore of greater than 4, which means they are
extremely good models according to ProQ validation criteria. Both structures also satisfied the
Ramachandran plot structure validation analysis. The predicted structures were 100% matched
with each other when superimposed with DaliLite pairwise. This shows that both structure
validation servers agreed on the same model. Structure analysis using ProFunc had found seven
motifs and active sites that indicate similar function of this protein with other known proteins.
Thus, this study has successfully produced a good 3D protein structure for the target enzyme.
Antibiotic resistance is an ever
increasing in worldwide problem nowadays. It is happened when t he exten-
sive use of antibiotics which will creates the selective pressure resulting from mutation of normal genes and
spreading of a variety of an antimicrobial resistance. Uses of Lactobacillus as probiotics or in starter cul-
tures may serve as hosts of antibiotic resistance genes, which could be transfer or resistance to multiple an-
tibiotics. Therefore it is important to screen the susceptible or resist ance towards antibiotics which will not
tr ansferable resistance genes. In the recent study, a total of 3 7 strains of Lactobacillus species isolated from
various milk and dairy products such as goat ’s milk, cattle ’s milk , human ’s milk , homemade yogurt and
commercial yogurt were examined for the a ntibiotic p rofile using Kirby Bauer method . The results of this
study show that human’s milk has a high number of Lactobacillus isolates resistant to ampicillin (75%),
vancomycin (62.5%) and gentamycin (62.5%). Whereas Lactobacillus isolated from cattle’s milk have re-
sistant to ampicillin (42.1%), vancomycin (42.1%) and susceptible to gentamycin (0%). But however,
goat’s milk stil l has lower percentage number of resistant to ampicillin (28.0%), vancomycin (14.3%) and
are susceptible to gentamycin (0%). These results indicate that ampicillin and vancomycin resistant seems
to be very common among Lactobacillus isolates bu t g entamyci n are still susceptible used. Vancomycin
resistant are more concerned because of the emerging problem in hospital and often described as one of the
last resorts against the infection caused by multidrug resistant pathogens. Therefore, lactobacilli as probi ot-
ics would be more monitor ing when applied in food industry and clinical especially for immune
compromised patients or during anti biotherapy. Acquisition and retransfer of resistance genes should be
addressed in the new safety aspects of probiotics uses.