This study focuses on isolated thermophilic Bacillus species’ adaptability and physiological diversity, highlighting their ecological roles and potential industrial applications. We specifically investigated their capacity to thrive in extreme conditions by examining their environmental tolerances and adaptations at the metabolic and genetic levels. The primary objective is to evaluate the suitability of these species for biotechnological applications, considering their resilience in harsh environments. We conducted a comparative analysis of the environmental adaptability parameters for various Bacillus species. This included examining growth temperature ranges, pH tolerance, oxygen requirements, carbohydrate fermentation patterns, colony morphology, enzymatic activities, and genetic properties. Controlled laboratory experiments provided the data, which were then analyzed to determine patterns of adaptability and diversity. The research revealed that Bacillus species could endure temperatures as high as 73°C, with a generally lower growth limit at 43°C. However, strains TBS35 and TBS40 were exceptions, growing at 37°C. Most strains preferred slightly alkaline conditions (optimal pH 8), but TBS34, TBS35, and TBS40 exhibited adaptations to highly alkaline environments (pH 11). Oxygen requirement tests classified the species into aerobic, anaerobic, and facultative aerobic categories. Genetic analysis highlighted variations in DNA concentrations, 16s rRNA gene lengths, and G+C content across species. Although glucose was the primary substrate for carbohydrate fermentation, exceptions indicated metabolic flexibility. The enzymatic profiles varied, with a universal absence of urease and differences in catalase and oxidase production. Our findings underscore thermophilic Bacillus species’ significant adaptability and diversity under various environmental conditions. Their resilience to extreme temperatures, pH levels, varied oxygen conditions, and diverse metabolic and genetic features emphasize their potential for biotechnological applications. These insights deepen our understanding of these species’ ecological roles and highlight their potential industrial and environmental applications.

(1) Background: This study summarizes the findings of two studies investigating the inhibitory effects of Pseudomonas aeruginosa strains from clinical and environmental sources against gram-positive and gram-negative bacteria and fungi. The studies also analyzed the correlation between enzyme production and inhibitory effects to gain insights into the antimicrobial capabilities of P. aeruginosa strains; (2) Methods: Both studies employed similar methodologies, including the use of disk diffusion and well diffusion methods to assess the inhibitory effects of P. aeruginosa strains against target pathogens. Enzyme production was analyzed through various biochemical assays to determine the diversity and frequencies of enzyme secretion among the strains; (3) Results: A comparative analysis of enzyme production in P. aeruginosa strains from clinical sources revealed significant variations in enzyme production, with hemolysin and protease being the most commonly produced enzymes. Gelatinase production showed lower rates, whereas chondroitinase and hyaluronidase were absent or occurred less frequently. In contrast, a comparative analysis of enzyme production in environmental isolates showed different patterns, indicating adaptation to environmental conditions. Pyocyanin production was absent in all environmental isolates. The inhibitory effects against gram-positive and gram-negative bacteria varied among different P. aeruginosa strains, with strain-specific variations observed. Limited inhibitory effects were observed against fungi, primarily toward gram-positive bacteria; (4) Conclusions: The findings highlight the strain-specific nature of inhibitory effects and enzyme production in P. aeruginosa strains. The correlation between enzyme production and inhibitory effects against gram-positive bacteria suggest a potential role of specific enzymes, such as hemolysin and protease, in the antimicrobial activity. The complexity of the relationship between enzyme production and the inhibition of different pathogens requires further investigation. The results emphasize the potential of P. aeruginosa strains as sources for antimicrobial strategies, particularly against gram-positive bacteria. Future research should focus on understanding the mechanisms underlying these inhibitory effects and exploring their therapeutic applications.

The Wadi Hanifah, a crucial aquatic ecosystem, has unfavorable consequences from natural occurrences and human activities. Recognizing the critical need for sustainable water management, this study provides an in-depth evaluation of wadi water quality. A comprehensive assessment was conducted, analyzing physical properties (temperature, pH, electrical conductivity, turbidity, color, and odor), chemical constituents (nitrogen compounds, ion concentrations, heavy metals), and bacterial diversity. The study found significant temperature fluctuations, particularly in sun-exposed or stagnant water areas. The water exhibited slight alkalinity and variable electrical conductivity and turbidity, indicating differing pollution levels. High ammonia and heavy metal concentrations suggested organic and industrial contamination, respectively. In addition, the prevalent fecal-indicator bacteria pointed to possible sewage or agricultural runoff. The research highlights the complex interplay of natural and anthropogenic factors affecting Wadi Hanifah’s water quality. It emphasizes the need for location-specific environmental management strategies focusing on pollution control and conservation to safeguard the wadi’s ecological health. This study provides vital insights for effective water resource management in Wadi Hanifah, serving as a model for similar ecosystems.

Seriphidium herba-alba (Asso), a plant celebrated for its therapeutic qualities, is widely used in traditional medicinal practices throughout the Middle East and North Africa. In a detailed study of Seriphidium herba-alba (Asso), essential oils and extracts were analyzed for their chemical composition and antimicrobial properties. The essential oil, characterized using mass spectrometry and retention index methods, revealed a complex blend of 52 compounds, with santolina alcohol, α-thujone, β-thujone, and chrysanthenone as major constituents. Extraction yields varied significantly, depending on the plant part and method used; notably, methanol soaking of aerial parts yielded the most extract at 17.75%. The antimicrobial analysis showed that the extracts had selective antibacterial activity, particularly against Staphylococcus aureus, and broad-spectrum antifungal activity against organisms such as Candida albicans and Aspergillus spp. The methanol-soaked extract demonstrated the strongest antimicrobial properties, indicating its potential as a natural antimicrobial source. This study not only underscores the therapeutic potential of Seriphidium herba-alba (Asso) in pharmaceutical applications but also sets a foundation for future research focused on isolating specific bioactive compounds and in vivo testing.

Coagulase-positive staphylococcus (CoPS), including methicillin-resistant Staphylococcus aureus (MRSA), poses a global threat. The increasing prevalence of MRSA in Saudi Arabia emphasizes the need for effective management. This study explores the prevalence of virulence-associated genes and antibiotic resistance patterns in CoPS. Nasal swabs from 200 individuals were collected, and standard protocols were used for the isolation, identification, and characterization of CoPS and coagulase-negative staphylococci (CoNS). Additionally, antimicrobial susceptibility testing and PCR were conducted. Bacterial growth was observed in 58.5% of participants, with 12% positive for CoPS and 30% positive for CoNS. Hospital personnel carriers showed a significantly higher proportion of CoNS compared with non-hospital personnel carriers. Non-hospital personnel CoPS strains displayed higher sensitivity to oxacillin than hospital personnel strains. Cefoxitin exhibited the highest sensitivity among β-lactam antibiotics. All isolates were sensitive to trimethoprim/sulfamethoxazole, rifampin, and quinupristin. Polymerase chain reaction analysis detected methicillin resistance genes in both non-hospital and hospital personnel MRSA strains. The coa and spa genes were prevalent in MRSA isolates, while the Luk-PV gene was not detected. A high prevalence of CoPS and CoNS was observed in both non-hospital and hospital personnel carriers. Occupational risk factors may contribute to the differences in the strain distribution. Varying antibiotic susceptibility patterns indicate the effectiveness of oxacillin and cefoxitin. Urgent management strategies are needed due to methicillin resistance. Further research is necessary to explore additional virulence-associated genes and develop comprehensive approaches for CoPS infection prevention and treatment in Saudi Arabia.

Nature-based wastewater treatment systems are increasingly implemented to support water reuse in arid regions, yet their effectiveness in removing viable culturable opportunistic pathogens remains insufficiently characterized. In this exploratory, culture-based study, we assessed bacterial population dynamics across a five-stage natural wastewater treatment system (Wadi Hanifa, Riyadh, Saudi Arabia), tracking culturable bacteria from secondary-treated influent to sand-filtered effluent. Water samples were collected at five sequential treatment stages and analyzed for physicochemical parameters, total culturable bacterial abundance, bacterial diversity, taxonomic composition, and antimicrobial susceptibility of persistent isolates. Total culturable bacterial counts decreased by approximately 1.1 log10 CFU mL‒1 across the system, accompanied by an approximately 50% reduction in observed isolate richness. The fecal indicator Escherichia coli was detected only in upstream and intermediate stages (sampling locations L3.1-L3.3) and was absent from downstream samples. In contrast, the opportunistic pathogen Klebsiella pneumoniae was recovered across all five treatment stages and accounted for 44.4% (8/18) of all morphologically distinct isolates grown on the selected culture media. Turbidity declined by 71% along the treatment train and showed a strong positive correlation with bacterial richness (Kendall’s τ = 0.84, p = 0.038), although this exploratory correlation should be interpreted with caution given the small sample size (n = 5 stages). Phenotypic antimicrobial susceptibility testing revealed multidrug resistance (MDR) in 62.5% (5/8) of K. pneumoniae isolates, although all remained susceptible to amikacin and meropenem. Under the conditions examined, multi-stage natural wastewater treatment substantially reduced overall bacterial abundance and diversity but did not eliminate viable, multidrug-resistant Klebsiella pneumoniae. The discordance between fecal-indicator removal and opportunistic pathogen recovery highlights system-specific limitations of indicator-based monitoring for assessing microbial safety in wastewater reuse systems. Given the limited isolate number (n = 8 K. pneumoniae) and the absence of molecular resistance-gene characterization, broader claims about wastewater as a dissemination pathway for antimicrobial resistance cannot be drawn from these data. These findings are based on a single cross-sectional sampling event and should be considered hypothesis-generating rather than confirmatory.