Listeriosis is a severe foodborne illness characterized by a fatality rate exceeding 30%, attributed to the pathogen Listeria monocytogenes. This study evaluated 160 lactic acid bacteria (LAB) isolated from Thai pickled crabs for their potential as agents against L. monocytogenes and for their probiotic properties and probiogenomic characteristics. Among these strains, strain DRC3-2 exhibited activity through the synthesis of bacteriocin DRC3-2, which significantly inhibited L. monocytogenes ATCC 19115 in spot-on-lawn assays. Phenotypic and whole-genome analyses revealed that strain DRC3-2 thrived in environments with 2-6% NaCl, pH values ranging from 3 to 9, and temperatures between 25 and 45°C. Based on average nucleotide identity (ANI) and digital DNA‒DNA hybridization (dDDH) values, strain DRC3-2 was taxonomically classified as Lactococcus lactis subsp. hordinae. The production of bacteriocin DRC3-2 peaked during the late stationary phase, following its synthesis in the early exponential growth phase. BAGEL4 analysis identified the putative novel bacteriocin DRC3-2 as lactococcin A and B, with respective bit-scores of 40.05 and 36.58. In silico safety assessments confirmed the nonpathogenic nature of strain DRC3-2 in humans, highlighting its absence of antibiotic resistance genes. Finally, this investigation underscores the novel bacteriocin DRC3-2 for application in the prevention and treatment of L. monocytogenes infections.
Listeria monocytogenes เป็นเชื้อก่อโรคที่มักพบในอาหารที่มีการปนเปื้อน สามารถอยู่รอดในสภาวะที่รุนแรง เช่น อุณหภูมิต่ำ ความเป็นกรดสูง ความเข้มข้นของเกลือสูง ซึ่งทำให้มีความเสี่ยงอย่างมากในระบบย่อยอาหารของมนุษย์ ดังนั้นจึงศึกษาแบคทีเรียกรดแลคติกที่มีความสำคัญในอุตสาหกรรมอาหารและยาเนื่องจากมีคุณสมบัติเป็นโพรไบโอติก และแบคทีเรียกรดแลคติกบางชนิดที่สามารถผลิตแบคเทอริโอซินหรือเปปไทด์ต้านจุลชีพที่มีฤทธิ์ทางชีวภาพ และแบคเทอริโอซินที่มีประสิทธิภาพในการยับยั้งแบคทีเรียก่อโรค ซึ่งถือว่าเป็นทางเลือกที่น่าสนใจแทนการใช้ยาปฎิชีวนะแบบดั้งเดิม เนื่องจากช่วยลดการพัฒนาการดื้อยาของแบคทีเรีย นอกจากนี้แบคเทอริโอซินยังมีความเสถียรสูง สามารถทนต่ออุณหภูมิที่รุนแรงและสภาวะเป็นกรดได้ อีกทั้งยังไม่เป็นพิษต่อเซลล์มนุษย์ การศึกษานี้จึงมุ่งหมายเพื่อศึกษาแบคเทอริโอซินชนิดใหม่จาก Lactococcus lactis subsp. hordinae DCR3-2 ซึ่งแยกได้จากปูดอง เพื่อประเมินฤทธิ์การต้านจุลชีพของแบคทีเรียชนิดนี้ และการวิเคราะห์ทางbioinformatics เพื่อยืนยันว่าสายพันธุ์ DCR3-2 มีความปลอดภัยสำหรับมนุษย์และมีคุณสมบัติโพรไบโอติก
คณะวิทยาศาสตร์
Bacteriocins are microbial peptides that demonstrate potency against pathogens. This study evaluated the inhibitory effects on pathogens and characterized the bacteriogenomic profile of strain TKP1-5, isolated from the feces of Anas platyrhynchos domesticus. Strain TKP1-5 was characterized using phenotypic traits, 16S rRNA sequencing, and Whole-Genome Sequencing (WGS). It exhibited growth in the presence of 2-6% NaCl, temperatures of 25-45°C, and pH levels ranging from 3 to 9. Based on ANIb, ANIm, and dDDH values, strain TKP1-5 was identified as Lactococcus lactis. Whole genome analysis revealed that strain TKP1-5 harbors the Nisin Z peptide gene cluster with a bit-score of 114.775. The antimicrobial spectrum of bacteriocin TKP1-5 showed inhibitory effects against pathogenic bacteria including Pediococcus pentosaceus JCM5885, Listeria monocytogenes ATCC 19115, Enterococcus faecalis JCM 5803T, Salmonella Typhimurium ATCC 13311ᵀ, Aeromonas hydrophila B1 AhB1, Streptococcus agalactiae 1611 and Streptococcus cowan I. Genomic analysis confirmed L. lactis TKP1-5 as a non-human pathogen without antibiotic resistance genes or plasmids. Furthermore, L. lactis TKP1-5 contains potential genes associated with various probiotic properties and health benefits. This suggests that L. lactis TKP1-5, with its antibacterial activity and probiotic potential, could be a promising candidate for further research and application in the food industry.
คณะทันตแพทยศาสตร์
Objective or Background: Dental caries is still one of the most significant dental problems worldwide, with prevalence rates up to 90% among children and adults. Cariogenic bacteria, especially Streptococcus mutans, is the primary microorganism involved in the pathogenesis through carbohydrate metabolism and biofilm formation, which are challenging to eradicate. Histatin-5 (HST-5), a human salivary antimicrobial peptide, has demonstrated antimicrobial activity against various fungal and bacterial pathogens. Phytosphingosine (PHS), an endogenous bioactive sphingolipid found in fungi, plants, and humans, also shows antimicrobial properties. This study aimed to evaluate the killing activity of HST-5 alone and in combination with PHS against S. mutans under biofilm-stimulating conditions. Materials and Methods: Antimicrobial activity against a planktonic culture of S. mutans was evaluated using a time-kill assay, and biofilm-forming capacity was confirmed by crystal violet staining assay. The killing ability against 24h pre-formed biofilm was determined using Transferable Solid Phase (TSP) pin lid model. Synergistic activity between HST-5 and PHS was evaluated using the checkerboard technique. Additionally, the cytotoxicity of the tested agent on human gingival fibroblast cells (hGFs) was assessed after 1 h of incubation using an MTT assay. Results: A time-kill assay revealed that both HST-5 and PHS exhibit time- and concentration-dependent activity against the planktonic form of S. mutans. PHS achieved over 90% killing activity within 15 min at 5 μg/ml, whereas HST-5 required 30 min to reach 90% killing at 20 μM. The biofilm formation capacity of S. mutans was confirmed. The inhibitory concentrations (IC50) of HST-5 and PHS against S. mutans biofilm were 25 μM and 13.5 μg/ml, respectively. A synergistic interaction between HST-5 and PHS, with IC50 values reduced by 8-fold and 16-fold, respectively. No cytotoxic effects were observed in hGFs cells at the concentration of the synergistic interaction. Conclusions: Therefore, the combination of HST-5 and PHS may enhance the effectiveness of anti-infective agents against S. mutans biofilm, potentially preventing the development of dental caries.
คณะศิลปศาสตร์
The innovation of aromatic and cooling inhalers stems from the widespread use of inhalers in modern times. This innovation aims to elevate the product to suit contemporary lifestyles, incorporating Thai identity in a way that resonates with the younger generation. The development focuses on enhancing scents using locally sourced Thai ingredients, adding value to Thai flowers and fruits. Various extraction methods are employed to preserve the fragrance for a longer duration. Additionally, borneol, camphor, and menthol are blended to provide a refreshing and cooling sensation. For the packaging, polymer clay is used to create the container, which is hand-molded and then baked to harden. Instead of a traditional cap, a fabric covering is used to introduce a unique and innovative alternative to conventional inhalers.