Clear Zone Research Articles

Differences in Inhibitory Effectiveness of Salam Leaf Extract (Syzygium Polyanthtalum) and Secang Wood Extract (Caesalpinia sappan L.) Against the Growth of Escherichia Coli Bacteria

Bay leaves (Syzygium polyanthum) and a second wood (Caesalpinia sappan L) are widely known to the public as natural antiseptics for prevention and treatment, including treating digesting diseases, one of which is diarrhea caused by Escherichia coli. Bay leaves and Secang wood can be used as antiseptics because they contain the active substance tannin. This research aims to determine the difference in the antibacterial effectiveness of 96% ethanol extract of bay leaves (Syzygium polyanthum) and 96% ethanol extract of second wood (Caesalpinia sappan L) on growth Escherichia coli bacteria. The type of research is experimental. The method used in this research is the Kirby-Bauer diffusion method. This method observes the clear zone produced from a blank disk that has been treated with bay leaf extract and second wood extract at a concentration of 30%, 60%, and 90% for incubation at 37?C for 24 hours. From the research results, it can be concluded that the ethanol extract of bay leaves with a concentration of 30%, 60%, and 90% with an inhibition zone diameter of 0 mm, 7,6 mm, and 9,6 mm. The second wood at a concentration of 30%, 60%, and 90% with an inhibition zone diameter of 10 mm, 11,3 mm, and 14 mm. The statistical test shows that the data is normally distributed with a parametric test ANOVA, p =0,00, which means that there is no significant difference in the diameter of the inhibition zone between the ethanol extract of bay leaves and the ethanol extract of second wood.

Endophytics Bacteria from Pangi Fruit (Pangium edule REINW.) and Its Potential as Producer of Antibacterial Compound

Natural antibacterials can be derived from various types of plants, one of which is the Pangi plant (Pangium edule REINW.). Pangi fruit contains an antioxidant and antibacterial compound that can inhibit bacterial growth. This study aims to determine the isolates of endophytic bacteria contained in Pangi fruit and its potential as a producer of antibacterial compounds against Escherichia coli and Staphylococcus aureus bacteria. This study used exploratory description research method. Results Isolation research of endophytic bacteria from Pangi fruit obtained seven isolates. Each Isolate has a different morphology both from the shape, color, edges, and colony elevation. Based on the results of antibacterial activity testing, each isolate of endophytic bacteria showed different clear zone diameters. Endophytic bacteria showed different clear zone diameters against E. coli (0.75 mm – 4.5 mm) and S. aureus (1 mm – 5 mm). Endophytic bacterial isolates That have the potential as antibacterial with the largest clear zone diameter are Isolate PA 2.1 (4.5 mm) against E. c oli and isolate PA 3.2 (5 mm) against the bacteria S. aureus. Based on the results of morphological characterization of isolate PA 1.1 has similarities with the genus Basillus sp., isolates PA 1.2, PA 1.3 PA 2.2, PA 3.1 and PA 3.2 have similarity with the genus Basillus sp. PA 3.2 has similarities with the genus Paracoccus alcaliphilus and isolate PA 2.1 has similarities with the genus Alcaligenes sp.

Evaluation of the antibacterial potential of mango (Mangifera indica) seed kernels in Bangladesh

Antimicrobial resistance is a global threat. On the other hand, Bangladesh produces high-quality mangoes, yet the mango coat and seed kernel, which contain medicinal components, remain unused. Therefore, this study investigated the antibacterial potential and toxicity of ethanol extracts from mango (Mangifera indica) seed kernels, which specifically target the bacterial strains Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Klebsiella sp. Amrapali variant mango seeds were collected, dried, ground into a fine powder, and extracted with ethanol at various ratios. The efficacy of the crude extract was tested via the disc diffusion method. The results demonstrated significant antibacterial activity against gram-positive bacteria (S. aureus and B. cereus), with clear zones of inhibition observed, especially in a dose-dependent manner. The pure crude extract inhibited the growth of S. aureus with a zone of 23 mm, identical to that produced by doxycycline. However, the extract exhibited limited activity against gram-negative bacteria (E. coli and Klebsiella sp.). Additionally, the extract was effective against multidrug-resistant S. aureus. The pure crude extract produced a 22.5 mm zone of inhibition against multidrug-resistant S. aureus, which was slightly smaller than that of gentamicin (23 mm) but larger than those of chloramphenicol (21 mm), vancomycin (20 mm), and tetracycline (16 mm). In vivo toxicity was assessed in mice, revealing no significant adverse effects on the hepatic structure or renal cortex at lower doses (100 μl of pure crude extract). However, higher doses caused mild histopathological changes in the liver and kidneys. These findings suggest that mango seed kernel extract holds promise as an alternative antibacterial agent, particularly against gram-positive and antibiotic-resistant bacteria, while being relatively safe at lower doses. Further research is needed to elucidate the active compounds, mechanisms of action, and broader applications of this extract in combating antibiotic-resistant bacterial infections.

Characterising the Chemical Composition of Bushfire Smoke and Implications for Firefighter Exposure in Western Australia

This study evaluates bushfire smoke as a workplace hazard for firefighters by characterising its chemical composition and potential health risks in Western Australia. Portable Fourier Transform Infrared (FTIR) spectrometry was used to measure airborne chemical concentrations at prescribed burns across five regions, including peat (acid sulphate) fire events. Samples were collected during both flaming and smouldering phases, as well as in perceived “clear” air resting zones. Results indicated that carbon monoxide (CO) was the dominant gas, reaching concentrations of 205 ppm at the fire front, followed by nitrogen monoxide (26 ppm) and methane (19 ppm). Peat fires produced distinct profiles, with ammonia (21.5 ppm) and sulphur dioxide (9.5 ppm) concentrations higher than those observed in typical bushfires. Smouldering phases emitted higher chemical concentrations than flaming phases 75% of the time. Even clear air zones contained measurable chemicals, with CO levels averaging 18 ppm, suggesting that firefighters are not free from exposure during rest periods. These findings highlight the need for fit-for-purpose respiratory protective equipment (RPE) and improved rest protocols to minimise exposure. The study underscores the importance of comprehensive health monitoring programs for firefighters to mitigate long-term health risks.

Enhanced antibiotic degradation using rGO composites under visible light photocatalysis

A robust reduced graphene oxide (rGO), polyaniline (PANI) with calcium (Ca) and magnesium (Mg) bimetallic nanocomposite was successfully prepared using an in-situ chemical facial reducing method and named rGO@PANI-Ca:Mg. Various spectroscopic techniques, including XRD, SEM, TEM, XPS, and supplementary methods, were utilized to characterize the catalyst phase, microstructure, and optical attributes. The composite's photocatalytic efficiency was assessed by degrading antibiotics such as ciprofloxacin (CP) and tetracycline (TC) using calcium peroxide (CaO2) under visible light irradiation. The rGO@PANI-Ca:Mg composite demonstrates superior degradation efficiency for CP, 45 %, and for TC, 70 %, achieving a correlation coefficient R² of 0.94 and 0.991 respectively. This performance surpasses that of pristine GO, rGO, and rGO@PANI. The heightened photocatalytic activity is ascribed to forming a heterojunction, effectively mitigating electron-hole pair recombination. The incorporation of CaO2 promotes the generation of additional active reactive oxygen species (ROS), particularly OH·, ·O2−, e-, h+, as verified by radical scavenging experiments, indicating an enhancement in the degradation and a potential mechanism is also suggested. The degradation rate of TC, CP, and real wastewater (RW) is about 71 %, 45 %, and 40.98 %, respectively. The composite demonstrates stability and reusability for up to three catalytic cycles. Our experiments also showed that when bacteria were treated with a 2 mg catalyst, the minimum inhibitory concentration (MIC) was determined to be at a 10−3 dilution. This MIC value represents the lowest concentration at which the catalyst effectively inhibited bacterial growth, as evidenced by clear inhibition zones.

α-Glucosidase Enzyme Inhibitory Activity of Extracts from the Fermentation of Endophytic Bacteria from Periwinkle (Catharanthus roseus (L.) G. Don) Leaves

Catharanthus roseus (L.) G. Don contain bioactive compounds that act as inhibitors against the α-glucosidase enzyme. This study aims to test the α-glucosidase enzyme inhibitor activity of fermented extract of endophytic bacteria from tapak dara leaves and identify the bacterial species. Endophytic bacteria were isolated using a direct planting method, resulting in eight isolates. The bacteria were fermented for 24-72 hours in nutrient broth media. Ethyl acetate was used to extract the fermented bacteria. Screening for α-glucosidase enzyme inhibitory activity was conducted using the TLC bioautography method. Four bacterial isolates (TD 1, TD 3, TD 4, TD 7) produced clear zones, qualitatively indicating that the isolates have inhibitory activity against the α-glucosidase enzyme. The IC50 results from the eight isolates showed that three isolates provided strong IC50 values: isolate TD 1 at 19.93 µg/ml, isolate TD 2 at 92.34 µg/ml, and isolate TD 4 at 13.94 µg/ml, compared to acarbose at 48.85 µg/ml). Molecular identification showed that isolate TD 1 was Pseudomonas oryzihabitans and isolate TD 4 was Staphylococcus warneri. This study concluded that endophytic bacteria from tapak dara leaves have the potential as a source of α-glucosidase enzyme inhibitor compounds for the development of antidiabetic drugs.

Characterization of Pectinase Enzyme Produced from Indigenous Yeast Isolates During Fermentation of Robusta Coffee Beans

The following research aims to understand indigenous yeast isolates that are pectinolytic, the effect of incubation time on pectinase enzyme activity, and the pH and temperature properties of pectinase enzymes obtained from indigenous yeasts from spontaneous fermentation of robusta coffee beans. The following type of research is an experiment through RAL (Completely Randomized Design). The results showed that testing of seven indigenous yeast isolates was pectinolytic and that the highest pectinolytic ability was isolate K24I7 with a clear zone diameter of 3.13 mm. The characterization results of the pectinase enzyme produced from isolate K24I7 were optimum at pH 5.5 with an enzyme specific activity value of 10.09 U/mg and optimum temperature in the range of 40oC-60oC with an average enzyme specific activity of 10.08 U/mg. The pectinase enzyme produced from isolate K24I7 is thermophile because it is still active at 70°C

Evaluation of the probiotic ability of Cellulolytic Bacillus subtilis SBMP4 (FSP20) isolated from waste-dump site in FIIRO, Lagos Nigeria

BACKGROUND: Current invention in the field of biotechnology includes research into the probiotic potentials of enzyme-producing bacteria species. OBJECTIVE: This study evaluated the probiotic ability of cellulolytic Bacillus subtilis SBMP4 isolated from waste dump site. METHODS: Isolated Bacillus species was screened for cellulolytic ability on carboxyl methylcellulose agar (CMCA), and hydrolysis efficiency was calculated. Probiotic ability of cellulolytic Bacillus species was carried out as follows: pathogenic potentials, bacteriocin producing ability, antibiotic susceptibility testing, gastric acid, and bile tolerance. Molecular identification was done by means of 16S rRNA gene sequencing, blast search analysis and phylogenetic analysis. RESULTS: Zone of clearance of 30 ± 2.08 mm on CMCA with hydrolysis efficiency of 114 % depicted the isolate’s cellulolytic potential. Bacillus subtilis SBMP4 showed γ-hemolytic phenotype with negative lecithinase activity. Antibacterial activity of bacteriocin observed against Staphylococcus aureus ATCC 25923 reference culture, had maximum inhibition zone of 14±1.0 mm at 72 hour of incubation. Substantial susceptibility towards 9 out of 10 commonly used antibiotics further depicted the isolate’s probiotic ability. Bacillus subtilis SBMP4 exhibited good gastric acid tolerance (pH 2.5) of 5.857 Log cycle/ml and good tolerance to 5 % and 10 % bile salt concentrations with 6.134 and 6.301 Log cycle/ml of viable bacteria cells. Molecular identification of the selected bacteria species revealed it to be Bacillus subtilis SBMP4 with RefSeq accession number NR_118383, showing maximum sequence similarity of 98%. CONCLUSION: Cellulolytic Bacillus subtilis SBMP4 possesses good probiotic ability and has the potentials of being applied as additive in livestock feeding to enhance overall productivity. KEYWORDS: Cellulolytic, Probiotic, CelA gene, Bacteriocin, Bacillus subtilis

Antioxidant Activity and Other Characteristics of Lactic Acid Bacteria Isolated from Korean Traditional Sweet Potato Stalk Kimchi.

The aim of this study was to examine the biological activity and probiotic properties of lactic acid bacteria (LAB) isolated from sweet potato stalk kimchi (SPK). Various LAB and Bacillus spp. are active in the early stages of the fermentation of kimchi made from sweet potato stalk. Four strains of LAB were identified, including SPK2 (Levilactobacillus brevis ATCC 14869), SPK3 (Latilactobacillus sakei NBRC 15893), SPK8 and SPK9 (Leuconostoc mesenteroides subsp. dextranicum NCFB 529). SPK2, SPK3, SPK8, and SPK9 showed 64.64-94.23% bile acid resistance and 78.66-82.61% pH resistance. We identified over 106 CFU/mL after heat treatment at 75 °C. Four strains showed high antimicrobial activity to Escherichia coli and Salmonella Typhimurium with a clear zone of >11 mm. SPK2 had the highest antioxidative potentials, higher than the other three bacteria, with 44.96 μg of gallic acid equivalent/mg and 63.57% DPPH scavenging activity. These results demonstrate that the four strains isolated from sweet potato kimchi stalk show potential as probiotics with excellent antibacterial effects and may be useful in developing health-promoting products.

Short communication: A multispecies bacterial-based direct-fed microbial alleviates Salmonella invasion and supports in vitro epithelial integrity.

Managing bacterial infections is of great importance in livestock production, particularly those caused by Salmonella enterica serovars Typhimurium or Dublin, which can impact both animal health and performance, as well as human food safety. Direct-fed microbials (DFM) can support gastrointestinal function and alleviate the potential negative effects of bacterial infections. In the present study, the capacity of a multispecies bacterial-based DFM containing Ligilactobacillus (formerly Lactobacillus) animalis 506, Propionibacterium freudenreichii 507, Bacillus licheniformis 809, and B. subtilis 597 to reduce S. Typhimurium ATCC14028 invasion was investigated using a co-incubation model with the HT29-MTX-E12 cell line (Exp. 1). Next, a possible antagonistic effect of the DFM against S. Dublin ATCC 41286 was evaluated using an in vitro agar well diffusion method following a co-incubation of 48h (Exp. 2). At last, a series of experiments were performed to evaluate how different doses (6.25 × 106, 2.50 × 107, or 1.00 × 108 CFU/well) of the DFM would support the integrity of intestinal epithelial cells challenged or not with S. Typhimurium ATCC14028 or hydrogen peroxide under a transepithelial electrical resistance (TEER) assay with Caco-2 cells (Exp. 3 and 4). In Exp. 1, BDP significantly (P < 0.001) reduced by 90.8% the invasion of S. Typhimurium into HT29-MTX-E12 cells, whereas viability of the potentially harmful bacteria was reduced by 21.0% (P < 0.0001). In Exp. 2, the antagonistic properties of BDP towards S. Dublin were confirmed by the detection of a clear inhibition zone (size = 8.6mm). Lastly, without challenge, the lowest dose of the DFM (6.25 × 106 CFU) provided the greatest support on the cells (treatment × hour; P < 0.0001). However, when the cells were challenged with S. Typhimurium, all doses alleviated the loss of integrity caused by the pathogen (treatment × hour; P < 0.0001). In cells challenged with hydrogen peroxide, the greater dose (1.00 × 108 CFU) supported the cells for a longer period of time (treatment × hour; P < 0.0001). These in vitro findings set the stage for exploring the potential benefits of using a novel DFM as a promising tool and strategy to mitigate Salmonella enterica infections in ruminants and improve animal health, food safety, and public health. Further in vivo confirmation needs to be developed to validate these preliminary in vitro results.

Patterns of Zoological Diversity in Iran—A Review

Iran is a country characterized by high biodiversity and complex biogeographic patterns. Its diverse landscape and steep climatic gradients have resulted in significant faunal diversity and high level of endemism. To better understand these patterns, we investigated the historical environmental drivers that have shaped Iran’s current geological and climatological conditions, and, consequently, have shaped the current zoological distribution patterns. Furthermore, we provide an overview of the country’s zoological diversity and zoogeography by reviewing published studies on its fauna. We analyzed nearly all available catalogs, updated checklists, and relevant publications, and synthesized them to present a comprehensive overview of Iran’s biodiversity. Our review reports approximately 37,500 animal species for Iran. We also demonstrated that the country serves as a biogeographic transition zone among three zoogeographical realms: the Palearctic, Oriental, and Saharo-Arabian, where distinct faunal elements intersect. This biogeographic complexity has made it challenging to delineate clear zoogeographical zones, leading to varying classifications depending on the taxon. The uplift of mountain ranges, in particular, has played a crucial role in shaping faunal diversity by serving as barriers, corridors, and glacial refugia. These mountains are largely the result of orogeny and plate collisions during the Mesozoic and Cenozoic eras, coupled with the development of the Tethyan Sea and the uplift of several ranges during the Miocene. Despite these insights, our understanding of biodiversity distribution in Iran remains incomplete, even for some well-studied taxa, such as certain vertebrate families and arthropods. We highlight the existing gaps in knowledge regarding zoogeographical patterns and propose approaches to address these gaps, particularly concerning less-studied species and the highly diverse group of insects.

Improvement of thermostable productivity ?-amylase from local isolate Bacillus licheniformis H14.

(28)Bacterial local isolates of Bacillus sp. were obtained from soil samples. Isolates were tested for thermostable alpha- amylase production on solid media; fifteen isolates were able to develop clear zone around the bacterial growth after floating the plates with iodine reagent (Lugol's solution). There were further tested in submerged culture which led to selection of Bacillus sp. H14since it was the most efficient .Microbial and biochemical tests showed that the local isolate Bacillus sp.H14was refered to the species B.licheniformis that signed as H14 was refered to the species B.licheniformis H14 .,To get ahigher yield of alpha – amylase(48.70unit/mg protein) production from the local isolate B.licheniformis H14 . This study used different mutation ways such as physical way by using the physical mutagen (ultraviolet light) and chemical way by using the chemical mutagen (nitrosoguanidine). Physical mutation results showed that the local isolate B.licheniformis HM14 get higher yield of alpha – amylase production(102.10 unit/mg protein) according to killing percentage (90%) while the chemical mutation results showed that the local isolate B.licheniformis HM4 get higher yield of alpha –amylase production(100.94 unit/mg protein) from the two mutant local isolates (HM14 and HM4)were the best carbon source starch (1.5%), peptone (1.5%) as nitrogen source, calcium chloride (0.02%), sodium chloride (0.05%), magnicium phosphate (0.05%), sodium di –hydrogen phosphate (0.16%), at initial pH (5) and inoculum size 1*108 cfu/ml at (50?C) For (72) hours, using shaking incubator at (150) rpm.

Polyethylene glycol enhanced antibacterial activity of EDTA and ethyl maltol blended PLA against Staphylococcus aureus for biodegradable active packaging

Poly (lactic acid) (PLA) has limited promise as a bio-based antimicrobial packaging material due to its lack of plasticization, which limits antimicrobial agent release and antimicrobial efficiency. PLA were plasticized with polyethylene glycol (PEG) and blended with ethyl maltol or ethylenediaminetetraacetic acid (EDTA) as antibacterial agents by melt extrusion. The effects of combining PEG, EDTA, and ethyl maltol on sheet properties and antibacterial activity were investigated. Incorporation of ethyl maltol created a dense and smooth homogeneous surface, while EDTA addition caused large pores in the PLA sheet microstructure impacting swelling degree, water solubility and surface hydrophilicity. Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) showed that both ethyl maltol and EDTA addition modified the amorphous and crystalline phases of plasticized PLA. FTIR results suggested interaction between the functional groups of PLA chains, PEG, ethyl maltol or EDTA which affected the glass transition temperature (Tg), degree of crystallinity, and thermal stability of PLA. Adding PEG into PLA-EDTA enhanced antibacterial activity against Gram-positive Staphylococcus aureus (reduction of 1.35 log CFU/mL from the initial inoculum). The higher water solubility of sheets corresponded to a suitable release rate and sufficient amounts of antimicrobial compounds against Staphylococcus aureus. In vitro antifungal testing, PLA-PEG-EDTA sheets did not exhibit a clear zone of inhibition but delayed Penicillium sp. spore formation until day 5 of incubation. PEG plasticized PLA sheets functionalized with ethyl maltol and EDTA showed potential as active biomaterials against food-borne pathogen bacteria Staphylococcus aureus.

Enhancing phosphorus availability and growth of green gram (Vigna radiata) in acidic red and laterite soil through liquid formulations of native phosphate solubilizing bacteria

Phosphorus (P) availability in acid soils is often limited due to its fixation with various soil components. This leads to low use efficiency of P fertilizers and raises environmental concerns when they are used in excess. Phosphate-solubilizing bacteria (PSB) have the potential to enhance P availability by solubilizing insoluble P forms. In this study, twenty-five PSB strains were initially isolated from acidic red and laterite soils in eastern India. Among them, ten bacteria formed a clear halo zone in Pikovskaya agar plates. The P releasing ability of these bacteria from different insoluble P sources was evaluated. The PSB strain AJ14, identified as Enterobacter sp., exhibited high P releasing capacity from tri-calcium phosphate, rock phosphate, ferric phosphate, and aluminum phosphate. Additionally, the strain demonstrated the ability to release zinc and potassium from insoluble sources. To improve the shelf life and efficacy of the PSB strain, liquid biofertilizer formulations were developed using polymeric additives such as polyvinylpyrrolidone, polyethylene glycol, glycerol, carboxymethyl cellulose, and tween 20. The liquid formulations showed enhanced survival and viability of the PSB strain compared to solid carrier-based biofertilizers. In a pot culture experiment with green gram plants, the liquid formulations significantly increased soil available P, dry matter yield, and P uptake by plants compared to the control and solid carrier-based biofertilizer treatment. Mitscherlich equation parameters indicated the greater effectiveness of the liquid formulations. The results suggest that liquid formulations of the PSB strain AJ14 can improve P utilization efficiency and plant growth in acidic red and laterite soils.

Synthesis and characterization of novel carboxymethyl tamarind kernel gum - Poly (vinyl alcohol)/guar gum-based hydrogel film loaded with ciprofloxacin for biomedical applications

The current study delineates the synthesis of hydrogel films comprised of carboxymethyl tamarind kernel gum (CMTKG), poly (vinyl alcohol) (PVA), and guar gum (GG) using glutaraldehyde (GL) as cross-linker. The hydrogel films were evaluated in terms of equilibrium swelling ratio (ESR), moisture content, thickness, wetting analysis, thermal, and mechanical analysis. The tensile strength value lies in the range of 95.80 to 149.07 MPa while elongation at break value lies in the range of 1.51 to 5.20 %. The FTIR spectroscopy confirmed the presence of hydrogen bonding between CMTKG, PVA, and GG components of hydrogel film. FE-SEM micrographs indicated the rough surfaces of hydrogel film. TGA-DTA analysis confirmed that the thermal stability of hydrogel film was found to be increased by incorporating the ciprofloxacin (CFX) drug into the hydrogel matrix. CFX was embedded in the best-swelled hydrogel film and in-vitro drug release behavior was studied at alkaline pH 7.4 phosphate buffer solution. It was found that the maximum drug release was to be 73 % after 24 h at pH 7.4. Moreover, the release data was fitted in various kinetic models such as the First-order, Higuchi, and Korsmeyer-Peppas models. The best-fitted Korsmeyer-Peppas model suggested that the release of the drug follows Fickian diffusion and the value of diffusion exponent (n) was determined to be 0.38. The cytocompatibility of the hydrogel film was analyzed by MTT assay while the antibacterial behavior of the hydrogel film against E. coli and S. aureus showed clear zone of inhibition area. Thus, the overall results indicated that CMTKG/PVA/GG hydrogel film have potential to be used in the biomedical applications.

Evaluation of azo dyes degradation potential of Staphylococcus strains: A strategy for dye-waste management

The current investigation aimed to identify the bacterial isolates that could prove helpful in the degeneration of harmful azo dyes from wastewater. The bacterial strains 1b, 1 m, and 4v could decolorize azo dyes up to 81 %, 79 %, and 87 % within 5 days. The degraded products by thin layer chromatography (TLC) showed Rf values of 0.89, 0.95, 0.90, 0.92, and 0.98 while the control showed an Rf value of 0.94. The comparison of the retention time of control and treated samples by the high-performance liquid chromatography (HPLC) system convinced that remarkable decolorization had occurred by the bacterial strains. The Fourier transform infrared spectroscopy (FTIR) analysis of the control and degraded samples was proof that the bond stretching occurred in the treated samples due to the action of bacterial strains. The release of compounds by bacteria i.e., 3-Aminobutanoic acid, pyrrolo pyrazine-1, 4-dione, and palmitic acid was inspected by Gas Chromatography-Mass Spectroscopy (GC-MS) analysis. No clear zones showed that the bacterial dye-degraded wastewater had no harm to the normal flora. At last, phytotoxicity was studied on Vigna radiata which had negative results. Given their pollutant degrading capabilities, these bacterial isolates are a good bioresource for green chemistry to exterminate azo dyes from the environment.

Unveiling the power of TiO2 doped ZnO nanomaterial as an effective antimicrobial solution in the leather industry

The surface protection of leather supplies is a major concern worldwide due to its susceptibility to microbial growth. Different methods are employed to protect leather, their results ends up with the environmental pollution and human safety issues. Nanoparticles with excellent antimicrobial potential can provide sustainable protection to leather accessories. The present work represented a comprehensive investigation into the preparation and characterization of titanium dioxide-doped zinc oxide (ZnO/TiO2 NPs) nanoparticles and their exploring as a potential antimicrobial agent in the leather industry. ZnO nanoparticles were synthesized through Sol-gel method by the reduction of zinc acetate dihydrate via black cardamom seed's extract and subsequently doped with TiO2. The optical, structural, and morphological features of nanoparticles were thoroughly scrutinized through UV–visible spectroscopy, XRD, FT-IR, and SEM-EDAX. The UV–visible spectrum showed enhanced performance between 300 and 350 nm and various peaks of the FT-IR spectrum, i.e. 3315.53, 1566.20, 1402.25, 1340.53, 1014.56, 921.97, 690.52, and 677.01 cm−1, revealed chemical bonds that prove the correct doping of TiO2 in ZnO nanoparticles. The characteristic peaks obtained from XRD at 2Ө of 32°, 35.5°, 37.2°, 47.9°, 55.6° 63.51°, and 70° intimated to the crystal planes of (100), (002), (101), (102), (110), (103), and (112), respectively. SEM-EDAX images revealed the roughly spherical but agglomerated structure of nanoparticles with size 45.44 nm. Furthermore, minimum inhibitory concentration (MIC), antimicrobial potential, and anti-biofilm potential analyses of nanoparticles, against all selected microorganisms (Aspergillus niger, Staphylococcus aureus, and Escherichia coli) provided valuable insights into physical and biological properties of the nanoparticles. The clear zones of inhibition (29–30 mm) against these pathogenic strains showed exceptional antimicrobial action of the ZnO/TiO2 NPs. Overall, these results provide an approachable method to synthesize ZnO/TiO2 nanoparticles and their antimicrobial ability will prove to be beneficial for the protection of leather materials from various microbial contaminations.

Optimization of the production of a new milk clotting enzyme by Aspergillus flavus thermophile on agro-industrial residues medium and characterization of the enzyme

This study focused on the optimization of the production of a milk clotting protease by Aspergillus flavus, isolated from a thermal station. The fermentation was carried out on wheat bran as a medium, followed by a partial characterization of the enzyme. The fungal isolate was screened for protease production based on clear zone hydrolysis on skim milk agar, and then it was identified as belonging to the genus Aspergillus based on its morphological characteristics. This identification was confirmed by molecular analyzes with 100% similarity with the A. flavus strain. After 7 days of fermentation, the crude extract is recovered by simple filtration. The production and optimization of the milk coagulant protease using wheat bran and agro-industrial waste as a medium was carried out using a statistical method of experimental design based on the Plackett and Burman matrices. The results showed that the optimal fermentation medium consisted of wheat bran (4% w/w), incubated at a temperature of 30 °C, with a pH of 5.0 after 6 days of fermentation. The enzyme was partially purified by ammonium sulfate precipitation, yielding an estimated proteolytic activity of 2,985 U. The partially purified protease exhibits optimal activity at pH 5 with hemoglobin as a substrate and an optimal temperature of 50 °C. The Lineweaver-Burk plot showed a KM value of 4.83 g/L and a Vm of 1,560 U. This enzyme causes very rapid coagulation of fresh cow’s milk with an optimum at 45 °C, a pH 7 and a concentration of 50 mM of calcium.

Antibacterial activity of coriander seeds extract (Coriandrum sativum) against the growth of Streptococcus mutans

Background: Streptococcus mutans is the main cause of dental caries, previously known as part of the normal flora in the oral cavity which plays a role in the process of fermenting carbohydrates to produce acid, and causes tooth demineralization. Chemical-based medicinal products such as toothpaste and mouthwash. Continuous use of chemicals can cause side effects for users such as hypersensitivity, therefore an alternative treatment from natural ingredients such as coriander seeds which can inhibit bacterial growth is needed. Objective: This research aims to determine the lowest concentration of coriander seed extract in 0,75%, 1.5%, 3% inhibiting the growth of Streptococcus mutans. Methods: This study was conducted by soaking the test discs in coriander seed extract concentrations of 0.75%, 1.5% and 3%. each disc was inserted into the bacterial culture to be cultured, incubated and seen whether there was a clear zone or not. Result: Test results showed a clear zone at a concentration 1.5% with an average diameter of 1.5 mm, at concentration of 3% an average diameter of 3.7 mm and at concentration of 0.75% did not show clear zone. Conclusion: Based on the results of the study, the lowest concentration of coriander seed extract was obtained which was able to inhibit the growth of Streptococcus mutans bacteria, is at concentration of 1.5%, the diameter of the inhibition zone of coriander seed extract had weak antibacterial activity.

Preparation of Nano-Sized Eucalyptus Leaves Extract and its Application on Cotton as Natural Dyes and Antibacterial Agents

Nano-emulsions of Eucalyptus globulus leaves extract in 96% ethanol and 96% methanol were successfully prepared using the method of homogenization at various speeds of 13,000 rpm, 15,000 rpm and 17,000 rpm, with the addition of non-ionic surfactant to prevent agglomeration. A phytochemical analysis showed the presence of tannin, phenol and flavonoids. The size of the resulting nano-emulsions was measured using a particle size analyser (PSA) prior to the dyeing of cotton fabrics using the two-dips-two-nips method. Antibacterial tests were carried out on the extracts and dyed fabrics. The results showed that nano-sized particles (&lt; 100 nm) were obtained from all extracts in both solvents used at all speeds. All dyed fabrics showed good levelness in a pale-brown colour with K/S values &lt; 1 for all samples under spectrophotometric measurement. The colour fastness of the dyed fabrics to washing and rubbing were good to very good, with grey scale values ranging between 4/5–5. Antibacterial tests in Staphylococcus aureus bacterium showed that the eucalyptus leaves extract solution exhibited antibacterial ability, as evidenced by the formation of clear zones around the wells. Much better antibacterial activity was demonstrated by the dyed fabrics. Changing the particle size to nano increased the effectiveness of the antibacterial activity of the Eucalyptus globulus. Results showed that the nano-sized eucalyptus leaves extract demonstrated a more significant antibacterial activity than dyeability.