ABSTRACT
Aims@#Recent discoveries have revealed that Glaciozyma antarctica PI12 has been discovered to encode numerous protein-coding genes that are crucial for thermal adaptation. However, more than 35% of the protein-coding genes for this species were identified as hypothetical proteins (HP). Nevertheless, over 35% of the protein-coding genes for this species were classified as hypothetical proteins (HP). Previous studies have documented the role of these uncharacterized proteins in the physiological regulation and cold adaptation of psychrophilic microorganisms. Thus, we aim to identify the structural features of the conserved HPs that were ideal for their function in response to temperature stress.@*Methodology and results@#Three conserved HPs of G. antarctica, designated GaHP2, GaHP3 and GaHP4, were cloned, expressed purified and their function and structure were evaluated. Functional analysis showed that these proteins maintained their activities at low temperatures below 25 °C, but at a lower reaction rate. Meanwhile, thermal unfolding assays revealed the stability of GaHP2 and GaHP4 at high temperatures (43 °C), suggesting their non-ATPbinding chaperone activity. The comparative structural analysis demonstrated that the HPs exhibited cold-adapted traits, most notably increased flexibility in their 3D structures. For GaHP2, the aromatic residues can be linked to its heat stability. GaHP4's cold shock domain implies it regulates gene transcription and translation during temperature fluctuations. @*Conclusion, significance and impact of study: @#This study has established the structure-function relationships of the G. antarctica HPs and provided fundamental experimental data highlighting their importance in thermal stress response by maintaining a balance between molecular stability and structural flexibility.
ABSTRACT
@#Mycobacterium tuberculosis (MTB) is a highly adaptive pathogen that emerged as a devastating and mortality-related disease agent. The limited efficacy of the Mycobacterium bovis BCG vaccine, antibiotics and intensive treatment to prevent mortality have piqued researchers' interest in host-pathogen interactions. Besides the emergence of multi-drug resistant TB as a drawback, the host immune responses could be successfully subverted and exploited by the MTB-host pathogenesis during the early stages of innate immunity. Factors contributing to mycobacterial pathogenesis are concomitant and multifactorial, including virulence factors such as adhesins, toxins and enzymes that drive the progression of MTB infection. Initially, alveolar macrophage (AM), which has been considered to restrain bacterial growth, facilitates the spread of disease through interactions with MTB. The progression to bacterial replication and systemic infection before the initiation of cell-mediated immunity (CMI) indicates a delay in the activation of adaptive immunity, which is crucial. The findings are supported by the bacterial multiplication and dissemination in the infected alveolar macrophage in animal models. On the other hand, mangrove plants have revealed a structural diversity and a plethora of compounds responsible for antibacterial, antifungal and antiviral activities. These may serve as potential bioactive compounds for anti-TB drugs. In this review, we discuss mycobacterial colonisation, tissue invasion and host inflammatory responses that lead to the pathogenesis of MTB, along with the potential bioactive compounds for alternative plant-derived anti-TB drugs. The mechanistic insights provide significant discoveries on the limitations of immunity, offering important strategies for developing immunomodulating drugs.
ABSTRACT
Aims@#Sabah’s red algae, Kappaphycus alvarezii is facing a problem whereby the production of seaweed is declining over the years due to a disease called ice-ice disease caused by Vibrio spp. Endophytic Bacillus strains have been widely studied for their potential as biocontrol agents against harmful pathogens. This study reports the genome sequence of the beneficial endophytic Bacillus strain VUMS1 isolated from the healthy K. alvarezii at Semporna Island in Sabah, attempting to determine its full biocontrol potential.@*Methodology and results @#The whole genome sequence showed that VUMS1 genome size is 3,754,982 bp with 3,854 protein-coding where 2,535 are genes with assigned functions. The analysis revealed the presence of genes that are involved in antimicrobial and antifungal activity such as fengycin, bacillibactin, bacilysin and lichenysin. The biocontrol potential of VUMS1 was evaluated against Vibrio parahaemolyticus isolated from the diseased K. alvarezii. Results showed that the inhibition zone of VUMS1 by cross-streaking method against V. parahaemolyticus was 21 ± 0.71 mm and the growth of V. parahaemolyticus treated with VUMS1 in a co-culture experiment decreased by 98% on day 5 of treatment.@*Conclusion, significance and impact of study@#The results of this work indicate that VUMS1 is affiliated as Bacillus altitudinis and it may contribute to the biocontrol activity against Vibrio spp. infection in K. alvarezii. This is the first report of endophytic Bacillus altitudinis from K. alvarezii with biocontrol properties. Future studies will determine the potential application of the B. altitudinis VUMS1 strain in biological control and growth promotion for sustainable seaweed farming.
ABSTRACT
Aims@#Dengue virus is a global pathogen that lacks an effective vaccine or therapy. Screening medicinal plants for anti-dengue properties provides a promising avenue to identify potent compounds. Mangroves, known for their resilience in harsh conditions, produce a diverse range of natural products with unique biochemical profiles, which hold potential for anti-dengue treatments. This study aims to evaluate the anti-dengue activity of selected mangrove plant species from Sabah against DENV2 NS2B-NS3pro, utilizing an enzymatic protease assay. @*Methodology and results @#Six mangrove species (Avicennia marina, Bruguiera gymnorrhiza, Ceriops tagal, Rhizophora apiculata, Rhizophora mucronata and Xylocarpus granatum) were investigated, with various plant parts subjected to aqueous and ethanol extraction. The results demonstrated significant anti-dengue activity in both aqueous and ethanolic extracts of the mangroves against DENV2 NS2B-NS3pro, with IC50 values ranging from 0.95 µg/mL to 6.24 µg/mL. Notably, the ethanolic extract of R. apiculata leaves exhibited the highest inhibition, with an IC50 value of 0.95 µg/mL. @*Conclusion, significance and impact of study@#These findings suggest that the ethanolic extracts from R. apiculata leaves hold promise as potential candidates for dengue treatment. This study underscores the importance of natural products as valuable sources for the development of novel anti-dengue treatments, highlighting the need to explore mangroves in the quest for effective therapeutic options.
ABSTRACT
Aims@#The study aims to investigate the bacterial community profiles on the surface of red algae (Kappaphycus alvarezii) and persistent bacteria that can adapt to long-term cultivation in a closed circulation system.@*Methodology and results@#Kappaphycus alvarezii explants were cultured in a controlled laboratory setting for 30 days to investigate related bacterial adaptability to controlled culture conditions. Bacterial isolates associated with seedlings were subjected to 16S rDNA amplification and sequencing, followed by the construction of a phylogenetic tree using MEGA X software. The results show distinct microbial composition between the first and 30th days. The derived phylogenetic tree features three dominant phyla: Proteobacteria (Vibrio and Thalassospira), Pseudomonadota (Pseudoalteromonas, Alteromonas, Grimontia, Ruegeria, Phaebacter and Bacterioplanes) and Firmicutes (Bacillus). A comparative examination of these two bacterial groups (day 1 and day 30) reveals evidence of persistent marine bacteria, such as the genera Vibrio, Pseudoalteromonas, Alteromonas, Phaaebacter and Bacterioplanes, that successfully adapt to long-term cultivation within closed circulation systems.@*Conclusion, significance and impact of study@#The findings of this study contribute to the understanding of bacterial ecology in the controlled red algae cultivation environment and also provide valuable insights into the optimization of an ideal closed cultivation system for sustainable K. alvarezii production, benefiting the seaweed industry.