Microbial and plant-mediated synthesis of metal and metal-oxide nanoparticles has produced an applied nanobiotechnology literature but almost no commercial products. This review asks why and what could change that outcome. The objective is to reframe biogenic nanoparticle production as a controllable bioprocess and to set out the evidence required for translation; its distinctive contribution is to treat the biomolecular capping layer, rather than the biological origin of synthesis, as the field's principal under-exploited quality attribute. The field has often focused on an incorrect primary variable. Biological synthesis is frequently justified as environmentally preferable because it avoids hazardous reductants and solvents. However, this claim is rarely quantified and is often unsupported by life-cycle evidence, which indicates that metal precursors and downstream separation, rather than reducing agents, dominate environmental burdens. The stronger advantage is process-based: biological synthesis can generate, in a single step, a complex biomolecular capping layer without separate functionalisation. This layer controls colloidal stability, ion release, protein corona formation and biological recognition, which this review argues should be treated as a critical quality attribute, yet is rarely specified or controlled. The entire production chain is examined as a bioprocess with defined upstream and downstream operations, identifying major sources of variability, including feedstock composition, growth phase, washing, drying and sterilisation, which may damage the capping layer after characterisation. Pilot-scale and techno-economic studies indicate that yield and downstream recovery, not synthesis chemistry, establish the cost floor. Antimicrobial evidence is also assessed, showing that many studies cannot distinguish nanoparticle effects from released ions or residual extracts because appropriate controls are missing. The principal conclusions are that reported antimicrobial activity frequently cannot be attributed to the particle itself without ion, extract and matched-chemical controls; that the capping layer is the most consequential uncontrolled variable; and that progress depends on treating synthesis as a bioprocess rather than on screening further species. Accordingly, a control hierarchy and minimum reporting dataset are proposed. Finally, translational maturity is evaluated across various applied areas and routes forward are highlighted, including engineered cell factories, continuous-flow biosynthesis, and omics- and machine-learning-guided process design.
Chilli leaf curl disease (ChiLCD), caused by a complex of begomoviruses transmitted by Bemisia tabaci, poses a major constraint to bell pepper (Capsicum annuum L.) production in India and worldwide. Rapid, sensitive, and field-deployable diagnostic tools are therefore critical for effective disease management. In this study, a recombinase polymerase amplification (RPA)-based assay was developed and applied for rapid detection of begomoviruses directly from crude plant extracts, with a SYBR Green–based qPCR used as a laboratory reference for quantitative assessment of target DNA. Symptomatic capsicum plants collected from the CPCT, ICAR–IARI, New Delhi, exhibited typical leaf-curl symptoms, and the virus presence was confirmed by electron microscopy. Genome characterization confirmed association of a begomovirus DNA-A component with a betasatellite related to ChiLCD complex viruses. Primers targeting a conserved coat protein (CP; AV1) gene region of begomoviruses were optimized for RPA. The assay demonstrated robust amplification of begomoviral DNA and sensitivity comparable to PCR, detecting viral DNA up to a 10−6 dilution and performing robustly using crude plant extracts. Field validation showed complete concordance with PCR results. A hydroxynaphthol–blue–based colorimetric-RPA-assay enabled clear visual detection without instrumentation. The SYBR Green qPCR exhibited high linearity and efficiency, enabling estimation of target DNA copy number under the tested conditions. In silico analysis indicated that the primers target a conserved region shared among the representative begomovirus sequences examined, suggesting potential applicability for detection of multiple begomoviruses. Collectively, this study provides a practical crude sap-compatible RPA-based approach for rapid detection of begomoviruses associated with ChiLCD in capsicum.
Traditional fermented dairy products are valuable sources of indigenous microorganisms with potential probiotic and biopreservative functions. This study evaluated the probiotic properties, safety characteristics, technological traits, antibacterial activity, and antifungal potential of Pichia kudriavzevii Y30 isolated from traditional buffalo butter collected in Guilan, Iran. The strain showed high survival under simulated gastrointestinal conditions, including acidic pH, bile salts, simulated gastric fluid, and simulated intestinal fluid, with survival rates of 84.45%, 89.31%, 78.68%, and 81.96%, respectively. P. kudriavzevii Y30 also exhibited desirable cell surface-associated properties, including hydrophobicity, auto-aggregation, co-aggregation, adhesion to Caco-2 cells, antioxidant activity, and biofilm formation. Safety evaluation showed gamma-hemolytic behavior and no decarboxylase activity toward histidine, arginine, or lysine. In antifungal susceptibility testing, the strain was susceptible to eight of the eleven tested antifungal agents and resistant to three. In addition, it produced exopolysaccharides and exhibited proteolytic and lipolytic activities, indicating potential technological value in fermented foods. The cell-free supernatant inhibited several foodborne pathogens, particularly Listeria monocytogenes. Moreover, P. kudriavzevii Y30 showed strong antifungal activity against Alternaria solani and A. alternata, with inhibition rates of 78.2% and 80.5%, respectively. This antifungal activity was partially stable under different pH and temperature conditions but was markedly reduced after Proteinase K treatment, suggesting the involvement of proteinaceous metabolites. Overall, P. kudriavzevii Y30 may be considered a promising multifunctional yeast with potential probiotic and bioprotective applications in fermented foods.
Technological properties and probiotic aptitude analysis of 10 Lactic Acid Bacteria (LAB) strains, including growth tests, indicated that all strains could survive at 3% NaCl, with optimal growth for strains Fructobacillus durionis_S128 and Lactococcus lactis_S7 at 6.5% NaCl. None grew at 4 °C, but strains Fructobacillus durionis_S24, Fructobacillus durionis_S28, Leuconostoc pseudomesenteroides_S135, and S7 demonstrated abundant growth at 45 °C. pH tolerance varied, with some strains growing at pH 2 and robust growth at pH 6.5 and 8. Enzymatic profiling revealed seven enzymes with varied activity across strains, notably leucine arylamidase and valine arylamidase. Strains Lactococcus lactis_S97, Leuconostoc mesenteroides_S159, S128, and Lacticaseibacillus paracasei_S43 showed favourable enzyme profiles. Antimicrobial tests showed effective inhibition against E. coli, B. cereus, P. aeruginosa, S. aureus and S. typhi, with all LAB strains sensitive to streptomycin and amoxicillin, exhibiting varying susceptibility to other antibiotics. Notably, all strains were resistant to penicillin and several to vancomycin; this resistance is not innocuous and represents a potential safety concern that requires genomic verification (screening for transferable resistance genes) before any application. Cell hydrophobicity indicates that three strains S28 (62.98%), S43 (59.68%), and S97 (58.88%) display hydrophobicity percentages greater than 50%. Concerning bile salt resistance, LAB strains showed high viability rates (50–98%), with the Fructobacillus durionis_S89 strain demonstrating the best resistance (97.67%) and the S97 strain the lowest (51.27%). The investigation for pepsin resistance revealed that all strains can withstand a 0.3% (w/v) pepsin solution at pH 3, maintaining viability rates between 38.40% and 48.5% after 3 h. In the same way, four strains were markedly more resistant than the others at pH 2: S97 (77.45%), S24 (67.52%), S135 (54,94%) and S43 (51.24%). The viability test of LAB strains exposed to a 0.5% pancreatin solution for 4 h at pH 8 showed over 50% resistance, with viability rates ranging from 75% to 95%. The S43 strain exhibited the highest rate at 94.86%, while 80% of the strains tested, including S128 (92.69%), S97 (90.43%), S7 (90.11%), S24 (88.71%), S28 (82.57%), S135 (82.39%) and S89 (82.26%) surpassed 80% viability.
