Background: In recent years, the potential role of probiotics has become prominent in the discoveries of neurotherapy against neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases. Lactic acid bacteria (LAB) exhibit neuroprotective properties and exert their effects via various mechanisms of actions. This review aimed to evaluate the effects of LAB on neuroprotection reported in the literature. Methods: A database search on Google Scholar, PubMed, and Science Direct revealed a total of 467 references, of which 25 were included in this review based on inclusion criteria which comprises 7 in vitro, 16 in vivo, and 2 clinical studies. Results: From the studies, LAB treatment alone or in probiotics formulations demonstrated significant neuroprotective activities. In animals and humans, LAB probiotics supplementation has improved memory and cognitive performance mainly via antioxidant and anti-inflammatory pathways. Conclusions: Despite promising findings, due to limited studies available in the literature, further studies still need to be explored regarding synergistic effects, efficacy, and optimum dosage of LAB oral bacteriotherapy as treatment or prevention against neurodegenerative diseases.

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be one of the main causes of hospital-acquired infections in all regions of the world, while linezolid is one of the only commercially available oral antibiotics available against this dangerous gram-positive pathogen. In this study, the antibacterial activity from 32 analogues of synthetic gamma-lactam heterocycles against MRSA was determined. Amongst screened analogues for the minimum inhibitory concentration (MIC) assay, compound MFM514 displayed good inhibitory activity with MIC values of 7.8–15.6 µg/mL against 30 MRSA and 12 methicillin-sensitive S. aureus (MSSA) clinical isolates, while cytotoxicity evaluations displayed a mean inhibitory concentration (IC₅₀) value of > 625 µg/mL, displaying a potential to becoming as a lead compound. In subsequent animal studies for MFM514, a single-dose oral acute toxicity test revealed an estimated mean lethal dose (LD₅₀) value of <5000 mg/kg, while in the mice infection test, a mean effective dose (ED₅₀) value of 29.39 mg/kg was obtained via oral administration. These results suggest that gamma-lactam carbon skeleton, particularly MFM514, is highly recommended to be evaluated further as a new safe and efficacious orally delivered antibacterial agent against MRSA.

Actinomycetes’ secondary metabolites have received considerable attention due to their many beneficial biological activities. However, many biosynthetic gene clusters in actinomycetes remain silent as they are not transcribed under standard laboratory conditions. Therefore, this study aims to introduce antibiotic elicitors to activate cryptic secondary metabolites in soil actinomycetes and screen them for antibacterial potential. A total of 20 cave and 10 mangrove soil actinomycete isolates were exposed to streptomycin or erythromycin at subinhibitory concentration (0.5–1048 μg/mL) in minimal media. The ethyl acetate extracts were subjected to high-performance liquid chromatography (HPLC) profiling to observe the effect of elicitors towards secondary metabolite production. As a result, 61.7% of the isolates showed a positive impact (appearance of ‘new’/increase in metabolite production) when elicitors were supplemented. These changes were more pronounced in erythromycin-induced media (63.3%) than in streptomycin (60.0%). Two isolates (CS3PT50 and CS3PT53) exhibited significant changes in the profile, with additional peaks detected at 210 and 245 nm, which may indicate the production of new metabolites. More antibacterial activities were observed from stimulated (26.7%) as opposed to non-stimulated isolates (10.0%), including 6 new activities, 1 improved, and 1 decrease in inhibitory. Furthermore, isolate CS3PT53 (0.5 mg/disc) displayed broad-spectrum activities, inhibiting S. aureus ATCC 25923 and S. Typhimurium ATCC 14028. The hit actinomycete isolates belonged to the genus Streptomyces (55.6%), Norcardia (22.2%), Norcardiopsis, and Saccharomonospora (11.1%). Overall, this study demonstrated that incorporating antibiotic elicitor at subinhibitory concentration could effectively trigger the production of cryptic secondary metabolites with antibacterial properties in soil actinomycetes.

Plant-beneficial microorganisms also known as endophytes colonize the inside healthy tissues of living plants and form mutualistic relationships with them. Endophytes are important components of the plant microbiome and give a variety of benefits to their hosts. Nam-Nam plant (Cynometra cauliflora), is an indigenous tree to Peninsular Malaysia with various medicinal properties. This study aimed to isolate and characterize endophytic bacteria from different parts of Nam-Nam plants such as leaves, stems, and roots. The ethyl acetate extracts from the endophytic bacteria were tested for their antibacterial activity against 7 bacterial pathogens. Plant growth promotion traits including starch hydrolysis, phosphate solubilization, nitrogen fixation, and indole-3 acetic acid (IAA) production were screened among the endophytic bacteria isolates. Molecular identification by 16S rRNA gene sequencing was performed for isolates with good antibacterial activity and plant growth promotion traits. A total of 33 endophytic bacteria comprising 27 Gram-negative and 6 Gram-positive bacteria were isolated. The antibacterial activity was demonstrated by 7 isolates in which R1L3 and TKL2 extracts exhibited significant activity against Bacillus cereus, Escherichia coli, and Proteus vulgaris. Production of IAA was exhibited by 15 isolates wherein R1S4 produced the highest IAA (20.62 µg/mL). Analysis of the 16S gene sequence revealed that RIR2, TKS2/R1L3, and R1S4/R1S5 belonged to Methylobacterium radiotolerans, Mycobacteroides abscessus, and Sphingomonas sp, respectively. The findings from this study showed that Nam-Nam plants harbored endophytic isolates with the potential to be established as a source of natural compounds that can be used to develop new anti-infection agents in the future. This is the first study to report on antibacterial activity and IAA production by endophytic bacteria from the Nam-Nam plants.

Aim: This paper reviews the different in vitro models of human intestinal epithelium that have been utilized for studying the adhesion and invasion properties. Problem Statement: The cell adhesion and invasion are the key mechanisms of bacterial pathogenicity that determines their possible routes of transmission. Numerous investigations related to the adhesion and invasion ability of bacterial isolates have been reported on monoculture human intestinal cells. However, the use of monoculture cells has several major disadvantages, such as the inability to reproduce the complex structure that defines the intestine and the inability to accurately predict the mechanism of bacterial adhesion and invasion. Approach: Co-culture models of human intestine have been developed as an alternative to improve the monoculture epithelial cell for adhesion and invasion studies, which provide more flexibility and overcome some of the limitations Conclusion: With the use of diverse in vitro approach, it could provide thorough information on different ability of bacterial adhesion and invasion and it could help to clarify the intricacy of hostpathogen interactions that underpin bacterial pathogenesis.

Bacteria have produced many important secondary metabolites, especially in the pharmaceutical industry. However, the increase in the rediscovery rate of the known compound has been inconvenient to researchers and the pharmaceutical industry. Nevertheless, genome mining in bacteria has uncovered several cryptic metabolic pathways that may be key to discovering new secondary metabolites. The conventional laboratory environment, however, limits the metabolic pathways of microorganisms, making it impossible for secondary metabolites to be produced. As a result, researchers began using epigenetics to change the expression of the genes that code for secondary metabolites in microorganisms. Using epigenetics modifiers, secondary metabolite gene clusters are activated without altering the bacterial DNA sequence. This review article focuses on the different epigenetic changes and how they affect gene expression to activate the synthesis of secondary metabolites in bacteria.