Current Microbiology

Tuan, Dang Anh; Masak, Jan

doi: 10.1007/s00284-025-04713-0pmid: 41524898

Device- and mucosa-associated candidiasis is difficult to cure because Candida biofilms shield cells from antifungals, leading to relapse and device failure. Standard treatment decisions are still largely guided by planktonic susceptibility tests, which poorly predict the drug exposure needed to clear mature biofilms. Here we synthesize evidence that natural-compound adjuvants can dismantle key biofilm defenses and outline design rules to rationalize biofilm-aware combination therapy. Across Candida albicans, non-albicans species and Candida auris, the most reproducible adjuvant effects fell into three themes: (1) reprogramming adhesion and morphogenesis, (2) disrupting membrane sterol homeostasis, and (3) weakening the extracellular matrix and efflux-mediated tolerance. When paired with standard antifungals, these actions frequently increase killing of established biofilms and reduce the exposures required for eradication. Local delivery approaches that concentrate actives at mucosal surfaces or device interfaces (nano- or surface-directed formulations) further improve intrabiofilm exposure while limiting systemic toxicity. We conclude that translation will require standardized biofilm assays, species-stratified testing and tighter links between biofilm pharmacology and clinically achievable exposure. The framework presented here is intended to help prioritize natural adjuvants and combinations most likely to benefit device-associated and mucosal candidiasis.

Suthar, Malika; Singh, Sanjay K.

doi: 10.1007/s00284-025-04689-xpmid: 41483037

Melanins are complex pigments generated when fungi, animals, plants, and bacteria oxidatively polymerize phenolic/indolic chemicals. Throughout history, this ubiquitous pigment has been utilized in various industrial applications attributed to its many qualities and uses across numerous sectors. This study focuses on the extraction and characterization of the melanin pigment of the rare Indian fungus Trichomerium bhatii NFCCI 4305. Potato dextrose broth was used for submerged fermentation of the pure fungal culture, and further, the black pigment was recovered from the biomass via alkali-acid treatment and then, purified. Through the use of UV spectroscopy, FTIR analysis, thermogravimetric analysis, and several physicochemical studies, the black pigment obtained was identified as “melanin”. Elemental analysis suggests that the pigment may actually be eumelanin. The purified melanin exhibited significant biological activities. Antimicrobial assays showed MIC values of 62.5 µg/mL for Raoultella planticola, 125 µg/mL for Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Candida albicansi and 250 µg/mL for Pseudomonas aeruginosa MTCC 2453. Antioxidant activity assessed using the DPPH radical-scavenging assay demonstrated a dose-dependent response (20–100 µg/mL) with an IC₅₀ of 4.35 µg/mL. Cytotoxicity analysis revealed only a mild, dose-dependent decrease in cell viability (56% to 40% across 5–320 µg/mL), indicating good biocompatibility. T. bhatii NFCCI 4305 melanin’s encouraging biological activity points to possible industrial uses for it. This is the first study that we are aware of those reports and describes melanin pigment from the Trichomerium genus.

Ketjarun, Kanapol; Chaiwanon, Juthamas; Vangnai, Alisa; Pachit, Pawara; Piapukiew, Jittra

doi: 10.1007/s00284-025-04702-3pmid: 41535373

Cassava (Manihot esculenta Crantz) is a major global food crop, with Thailand as a leading producer. Plant growth-promoting rhizobacteria (PGPR) offer a sustainable alternative to chemical fertilizers, but the use of non-native PGPR may lead to poor efficacy and ecological disruption. To address this, we isolated and screened 110 native bacterial strains from arbuscular mycorrhizal (AM) fungal spores and rhizospheric soil (RS) collected from organic cassava fields in northeastern Thailand. Isolates were evaluated for IAA production, exopolysaccharide (EPS) production, ammonia production, siderophore production, and phosphorus and potassium solubilization. AM isolates showed higher siderophore production, while RS isolates exhibited greater EPS production. This work presents the first report of Pantoea dispersa isolated from cassava fields in Thailand, with strain CU_RS19 identified as a promising candidate due to its strong potassium-solubilizing ability and non-pathogenic status under the Pathogens and Animal Toxins Act of Thailand (2015). Outdoor pot experiments demonstrated that P. dispersa CU_RS19 significantly enhanced cassava growth, increasing root length (38.4%), root dry biomass (105%), stem diameter (30.3%), stem height (62.5%), stem dry biomass (68.1%), and leaf dry biomass (38.8%) compared to the control. Co-inoculation with Serratia marcescens CU_AM17 did not provide additional benefits, likely due to the absence of AM fungi in the experiment. These findings suggest that P. dispersa CU_RS19, a rhizospheric soil bacterium, is a promising PGPR for cassava cultivation. The absence of AM fungi treatments and the lack of bacterial colonization confirmation are limitations of this work. Future field studies incorporating P. dispersa CU_RS19, the AM-associated bacteria S. marcescens CU_AM17 and AM fungi are recommended to validate their efficacy under diverse agricultural conditions and explore tripartite interactions for enhanced plant growth.

Maqueda-Cabrera, Edson E.; Cuéllar-Cruz, Mayra

doi: 10.1007/s00284-025-04715-ypmid: 41507568

The clinical management of Nakaseomyces glabratus is becoming increasingly difficult because of its intrinsic and acquired resistance to multiple antifungal drugs, particularly azoles. This situation highlights the urgent need for new antifungal agents. In this study, the antifungal efficacy and toxicity profile of an organometallic compound, named FE1, was evaluated in the in vivo model Galleria mellonella infection model. Larvae were inoculated with a standardized suspension of N. glabratus CBS138 and treated with FE1 or fluconazole at different concentrations (0.4, 4.0, and 20 mg/kg). Survival and fungal burden (CFU/larva) were monitored at defined time points post-inoculation (24, 120 and 360 h). The results obtained in this study show that the model of N. glabratus infection in G. mellonella is suitable to evaluate toxicity, antifungal efficacy and evolution of the infection in response to antifungal treatments. In this context, compound FE1 showed significant antifungal activity, superior to that of fluconazole in parameters evaluated, such as survival and fungal burden, while melanization was monitored as a qualitative visual indicator of infection progression. The dose-dependent response observed in both survival and CFU/larva reduction assays, together with the complete protection in the groups treated with 20 mg/kg FE1 suggests a high therapeutic potential of this compound against N. glabratus infections.

Yang, Yun-hui; Liao, Chun-fang; Hyde, Kevin David; Manawasinghe, Ishara Sandeepani; Mckenzie, Eric; Al-Otibi, Fatmah; Bhunjun, Chitrabhanu Sharma; Kakumyan, Pattana

doi: 10.1007/s00284-026-04720-9pmid: 41543757

Ge, Dongying; Cai, Wenchao; Shan, Chunhui; Liu, Zhongjun; Guo, Zhuang

doi: 10.1007/s00284-026-04719-2pmid: 41553518

In order to understand the influence of different parts of the low-temperature Daqu (LTD) on the fermentation of Jiupei. In this study, Jiupei was prepared separately using the peel and core of Houhuo LTD. The physicochemical properties, sensory characteristics, and microbial community structures of the two groups of Jiupei were subsequently analyzed using conventional physical and chemical assays, electronic tongue sensing, electronic nose sensing, and high-throughput sequencing. In terms of physicochemical indicators, the pH (3.08), protein content (5.97%), and reducing sugar content (3.70%) of peel-fermented Jiupei were significantly higher than those of core-fermented Jiupei (P < 0.05). In terms of taste, peel-fermented Jiupei exhibited significantly higher sourness, astringency, and aftertaste-A, whereas core-fermented Jiupei showed significantly stronger bitterness and umami intensity (P < 0.05). Moreover, core-fermented Jiupei was richer in aromatic compounds, whereas peel-fermented Jiupei contained higher levels of organic sulfides (P < 0.05). Finally, microbial analysis revealed that core-fermented Jiupei had significantly higher bacterial richness, bacterial diversity, and fungal diversity than peel-fermented Jiupei (P < 0.05). Notably, peel-fermented Jiupei was enriched with Lactobacillus (86.38%) and Saccharomycopsis (70.94%), while Bacillus (6.04%), Saccharomyces (29.32%), and Pichia (2.35%) showed dominance in core-fermented Jiupei (P < 0.05). Correlation analysis revealed that Lactobacillus, Bacillus, Lentilactobacillus, Saccharomycopsis, and Saccharomyces were the key genera influencing the physicochemical and sensory qualities of Jiupei. These findings demonstrate that core-fermented Jiupei exhibits richer microbial diversity, stronger umami taste, and higher aromatic compound levels. From this, it can be seen that Jiupei was prepared using the core of Houhuo LTD is beneficial for the growth of microorganisms and the formation of flavor quality in the Jiupei.Graphical abstract[graphic not available: see fulltext]

Mabeo, Onalenna Refilwe; Tsholo, Karabo; Bezuidenhout, Cornelius Carlos; Molale-Tom, Lesego Gertrude

doi: 10.1007/s00284-025-04696-ypmid: 41524795

The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are key multidrug-resistant organisms increasingly recognized outside clinical settings. Their persistence in wastewater raises concerns regarding the efficacy of conventional treatment processes and the dissemination of antimicrobial resistance. This study aimed to detect and quantify ESKAPE pathogens in wastewater treatment plants (WWTPs) and downstream environments using agar-based enumeration and real-time PCR (RT-PCR). Culture methods detected all targeted species, with Enterobacter spp. being most abundant and A. baumannii least prevalent. RT-PCR quantified four species (E. faecium, S. aureus, K. pneumoniae, and A. baumannii), identifying K. pneumoniae as dominant. Both approaches revealed higher concentrations in influents that declined after treatment, although RT-PCR indicated elevated downstream levels, suggesting incomplete removal. The highest removal efficiency (100%) was observed for S. aureus and A. baumannii in WWTPs B and J, and the lowest (54.1%) for S. aureus in WWTP K. Integrating culture and molecular methods improved detection sensitivity and provided complementary insights. These results demonstrate that conventional treatment may not fully eliminate ESKAPE pathogens and underscore the need to include them in wastewater-based surveillance for antimicrobial resistance monitoring.

Mukherjee, Debasree Basu; Narayanaswamy, Sharadamma; Rangappa, Nagesh Babu

doi: 10.1007/s00284-025-04716-xpmid: 41530403

Despite significant advancements over the years, Tuberculosis (TB) remains a global threat, especially in low and middle-income countries. The causative agent, Mycobacterium tuberculosis H37Rv, adapts to itsenvironment through Nucleoid-associated proteins (NAPs), which play a crucial role in organizing the bacterial chromosome and regulating gene expression. It is one of the prevalent classes of DNA-binding proteins with dynamic functional characteristics that rearranges the bacterial DNA structure to respond to various stimuli. A notable characteristic of mycobacterial NAPs is their limited sequence similarity with those found in other species, which has posed challenges in their identification. Mycobacterial NAPs, including HupB, Lsr2, EspR, mIHF, Dps, NapA, NapM and MDP2, are involved in essential processes like transcription, growth, chromosomal architecture, antibiotic resistance, and immune evasion. These proteins, often structurally distinct from their counterparts in other species, exhibit dynamic functional characteristics that make them vital for the survival of mycobacteria, especially for M. tuberculosis. However, studying these NAPs presents unique challenges due to their limited sequence conservation. This review aims to explore the diverse roles of NAPs in M. tuberculosis, shed light on the complexities of gene regulation, and discuss the potential for targeting NAPs in future anti-TB therapies.

Hassan, Fakhrul; Khan, Abbas; Suleman, Muhammad; Khan, Faez Iqbal; Gul, Ijaz

doi: 10.1007/s00284-026-04729-0pmid: 41553557

Bacteriophytochrome-derived near-infrared fluorescent proteins (NIR FPs) provide deep tissue penetration, low autofluorescence, and endogenous biliverdin compatibility, enabling non-invasive visualization of viral processes in living systems. Engineering advances (iRFPs, monomeric miRFPs, photoactivatable PAiRFPs) have improved brightness, stability, and genetic encodability for robust use in mammalian models. These reporters support real-time tracking of infection dynamics and host-virus interactions and power diagnostic platforms including reporter viruses, CRISPR-based assays, and nanotechnology-enhanced biosensors. Multimodal integration with photoacoustic tomography and PET further extends their translational utility. Remaining challenges include brightness/photostability limits and the need for broader translational validation, yet progress in structure-guided mutagenesis, computational/AI-assisted protein design, and hybrid imaging strategies promises to close these gaps. This mini-review synthesizes the design principles, viral imaging/detection use cases, and translational prospects of bacteriophytochrome-derived NIR FPs, highlighting their potential to advance viral surveillance, therapeutic evaluation, and precision diagnostics.Graphical AbstractEngineering of bacteriophytochrome-derived NIR FPs (iRFPs, miRFPs, PAiRFPs) as versatile tools for viral imaging, biosensing, and diagnostics.[graphic not available: see fulltext]

Mao, Ying; Zhou, Tian-Qian; Bai, Xu; Xu, Qing-Fang; Gao, Xiu; Liang, Yu-Peng; Zhao, Ya-Lan; Cai, Jian; Zhu, Ling

doi: 10.1007/s00284-026-04730-7pmid: 41554940

Passiflora edulis (P. edulis Sims) is prevalent in tropical regions, and its distinctive taste and aroma are highly appreciated due to its unique nutritional profile. With the increasing recognition of the added value of P. edulis Sims wine, an expanding number of researchers have begun to focus on the related studies concerning the brewing process of this wine. Isolating high-quality yeast strains from the natural fermentation broth of P. edulis Sims is crucial for this purpose. In this study, 38 yeast strains were isolated and purified from the fermentation broth of P. edulis Sims. Nine yeast strains were selected using WL medium for further analysis. The fermentation characteristics of these strains were evaluated based on their production of esters, ethanol, and hydrogen sulfide (H2S), as well as through tolerance tests. The results indicated that the nine yeast strains exhibited favorable fermentation performance characterized by low H2S production while demonstrating high levels of ester and ethanol production, along with certain antimicrobial activity. Among these strains, GZH−20 displayed a notably low capacity for H2S production coupled with exceptional abilities in both ester and ethanol generation. Furthermore, this strain demonstrated good tolerance under various conditions, including pH levels ranging from 2.8 to 3.8, a glucose concentration of 200 g/L, and varying sulfur dioxide (SO2) concentrations between 60 g/L and 360 g/L; it showed superior capacities for producing esters and ethanol under these conditions. Molecular identification confirmed that this strain is classified as Wickerhamomyces anomalus. These findings hold significant implications for advancing our understanding of specialized yeasts involved in P. edulis Sims wine production.