Sumardi Sumardi

This study reports the first isolation of an Enterobacter cloacae complex (ECC) strain, closely related to Enterobacter hormaechei (99.86% 16S rRNA identity), associated with bacterial blight symptoms in rice in Lampung, Indonesia. Acknowledging 16S rRNA limitations within ECC, species identification is reported cautiously, while pathogenicity profile fulfilled Modified Koch's Postulates. To address chemical bactericide limitations, we developed sustainable multiphase nanoparticles from chicken eggshell waste through mechanical and thermal decomposition approaches. The produced nanoparticles were characterized using XRD, TEM, FTIR, SEM-EDS, PSA, and UV-DRS. The results showed that the nanoparticles consisting of Ca(OH)2, CaO, and β-tricalcium phosphate, with a dimension of 11–31 nm (XRD) and 20–23 nm (TEM). The FT-IR/EDS data confirmed OH⁻, Ca, O, and P elements, while UV-DRS showed a bandgap energy of 5.96 eV. Descriptive statistical analysis (n=6) evaluated antibacterial activity via disk diffusion (20 µg/disk) against the ECC isolate, compared to ampicillin sulbactam (SAM 20). Nanoparticles yielded a mean inhibition zone of 10.06±0.02 mm for responsive replicates, demonstrating moderate activity. Within the zones, bacterial cells showed morphological damage, likely caused by Ca²⁺ and OH⁻ release, inducing membrane disruption and oxidative stress. Furthermore, spatially graded element distribution (Ca, O, P) and β-TCP as a controlled release matrix support sustained bioactivity. These findings reveal eggshell-derived nanoparticles as a promising, economical, and environmentally friendly antibacterial agent for sustainable rice disease management.

Ekstrak etanol daun kemangi (Ocimum basilicum L.) diketahui memiliki senyawa fitokimia yang memiliki efek antibakteri. Penggunaan antibiotik untuk pengobatan infeksi dapat memberikan efek samping. Perlunya pengobatan lain, salah satunya berasal dari bahan alam seperti ekstrak etanol daun kemangi yang diformulasikan menjadi bedak dingin. Penelitian ini bertujuan untuk mengetahui karakteristik fisik bedak dingin meliputi warna, aroma, tekstur, daya lekat dan memperoleh konsentrasi yang paling efektif terhadap pertumbuhan Escherichia coli, Staphylococcus aureus, dan Staphylococcus epidermidis. Metode difusi disk (Kirby Bauer) digunakan dalam uji aktivitas antibakteri dengan konsentrasi 5%, 10%, 15%, daan 20% sebanyak dua kali pengulangan dengan menggunakan kontrol positif (tetrasiklin) dan kontrol negatif (aquades). Data yang diperoleh dianalisis varian dua arah (ANOVA) kemudian apabila terdapat perbedaan nyata antar perlakuan dilanjut dengan uji lanjut Tukey untuk mengetahui perbedaan antar perlakuan pada α= 5 %. Hasil penelitian karakter fisik menunjukkan bahwa bedak dingin ekstrak etanol daun kemangi sesuai dengan persyaratan uji homogenitas, uji pH (4,5-6,5), stabilitas yang baik dan uji daya lekat yang sesuai. Hasil uji antibakteri menunjukkan bahwa semua konsentrasi bedak dingin ekstrak etanol daun kemangi 5%, 10%, 15%, dan 20% tidak memiliki aktivitas antibakteri terhadap bakteri Escherichia coli, Staphylococcus aureus, dan Staphylococcus epidermidis. Meski demikian, penelitian ini berkontribusi dalam memberikan data ilmiah bahwa formulasi topikal tertentu mungkin tidak mengoptimalkan potensi antibakteri dari suatu ekstrak.

The search for environmentally friendly antibacterial materials with excellent performance that does not make bacteria resistant is still a challenge. In this research, S/CuO/GO nanomaterials were prepared by the sol-gel method using pectin as an emulsifying agent. After freeze-drying and calcining processes, the prepared nanomaterials were characterized using XRD, UV-vis diffuse reflectance, FTIR, SEM-EDX-mapping, and TEM. The Gram-positive and Gram-negative antibacterial tests were done using the MIC and Kirby-Bauer disc diffusion methods. The characterization data showed that the antibacterial material has met the nano-size of 16 nm, and its antibacterial tests using the MIC method gave promising results. Furthermore, the best MIC test results for Escherichia coli and Bacillus sp. bacteria were obtained at a concentration of 0.01000 and 0.00125 mg/mL, respectively. In addition, the Kirby-Bauer disc diffusion antibacterial testing for E. coli and B. subtilis produced a clear zone of 12 and 18 mm with an exposure time of 15 and 30 min, respectively. These results proved that S/CuO/nGO is potent for antibacterial application.

Cocoa honey, a byproduct of cocoa bean processing, contains high sugars and minerals; thus, it has potential as a fermentation medium. This research investigated the potency of cocoa honey as probiotic media for promising yeast probiotic Saccharomyces boulardii. The growth of S. boulardii in the cocoa honey medium was optimized through response surface methodology employing a central composite rotatable design to obtain maximum cell production and antimicrobial activity. The effects of inoculum size (2–5%), sucrose addition (2.0–3.0%), and fermentation time (5–20 h) were evaluated. The agar diffusion technique assessed the cocoa honey medium's antibacterial activity. Results showed that these independent variables significantly affected the production of S. boulardii cells and their microbial activity against Escherichia coli. The optimal values generated by the model with a desirability value of 0.908 were 20 h of fermentation time, 2% of sucrose addition, and 2% of inoculum size. The maximum yeast count (log10 8.07 cells/mL) and antibacterial activity (4.88 mm) were reached under these optimized conditions, which agreed with the predicted value of the RSM model. This study provided valuable information on the potency of cocoa honey as a fermentative medium for applying S boulardii to develop a probiotic drink.

Anthracnose and crown rot caused by Colletotrichum sp and Phytopthora sp fungi are one of the main problems in guava and pineapple cultivation. This research aims to determine the growth of Trichoderma isolates (T14 and T7834), the potential of the isolates as biocontrol agents and the activity of lipase and chitinase enzymes. Research data was analyzed descriptively qualitatively. This study concluded that the growth graph of Trichoderma isolates began with an increase in mycelium dry weight on day 3, on day 12 the dry weight of mycelium increased rapidly, on day 21 the dry weight of mycelium was constant, on day 30 the dry weight of mycelium decreased. The results of the Trichoderma compatibility test were able to inhibit the growth of the fungus Phtyopthora sp. and Colletotrichum sp. so it is effective as a biocontrol agent to control the pathogenic fungus Phytoptora sp. and Colletotrichum sp. in vitro. However, Trichoderma T7834 is unable to inhibit the growth of the Colletotrichum fungus, so it is less effective as a biocontrol agent. The results of the enzyme activity test showed that Trichoderma was only able to produce the lipase enzyme, so the two isolates had the potential to be candidates for biocontrol fungi.

Phosphorus is a very important nutrient for plants. However, most of the phosphorus is bound by soil colloids and is insoluble, so the role of phosphate solubilizing bacteria is needed to release the bound phosphate. This study aims to isolate, characterize, and test the pathogenicity of phosphate solubilizing bacterial isolates. This research used an exploratory method including taking soil samples, bacterial isolation, calculating the density of bacterial colonies, calculating the phosphate solubility index value and selecting potential bacteria, morphological and physiological characterization, and pathogenicity test. The results showed that the colony density was 3,2 x 103 CFU/g with phosphate solubility index values ranging from 1,38-3,65. The colony with the highest phosphate solubility index value is JE1 with a value of 3,65; JE2 with a value of 3,63; JE3 with a value of 3,13; JE4 with a value of 3,08; and JE5 with a value of 2,94. Colonies have an irregular shape with undulate edges, the colony color is predominantly white with umbonate, raised and flat elevations. Most isolates have short bacillus cells that are Gram negative, do not form spores, are able to ferment glucose, produce the enzyme catalase, and are not motile. The pathogenicity test showed that only the JE1 isolate was not pathogenic to tobacco leaves.

Staphylococcus aureus is a type of bacteria that causes an increasing number of infections in hospitals, particularly in diabetic ulcers. Over the last few decades, there has been an alarming increase in the prevalence of pathogen strains of Staphylococcus aureus resistant to antibiotics such as Vancomycin. This study aimed to identify the presence of the vanA gene, which is responsible for the mode of Vancomycin resistance in Staphylococcus aureus Lampung isolate. Ulcer swab was collected from 32 patients with ulcer complications from surgical Installation, Internal Medicine, Home Diabetes Wound Clinic and Diabetes Wound Center in Bandar Lampung. Among the total ulcer swab, 12 samples of S. aureus were identified and subjected to the Minimum Inhibitory Concentration test to identify Vancomycin Resistant Staphylococcus aureus and evaluated the vanA gene by Polymerase Chain Reaction. To detect the presence of the vanA gene, a Polymerase Chain Reaction was performed on Staphylococcus aureus, Vancomycin-Resistant Staphylococcus aureus, and Vancomycin-intermediate Staphylococcus aureus using a specific primer arrangement. There were two samples of Vancomycin- Resistant Staphylococcus aureus and one sample of Vancomycin-intermediate Staphylococcus aureus from the Minimum Inhibitory Concentration test but only one sample tested positive for the vanA gene on Polymerase Chain Reaction. There is Staphylococcus aureus resistance to Vancomycin in Lampung isolate and the vanA gene was detected in some resistant isolates. The arrangement of the vanA gene in the Lampung isolate is different from that of the vanA gene in other places isolates.

Identifying the most effective material with antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) is a challenging task considering the rising concerns about drug resistance. Various experiments through in vitro and in vivo studies to obtain antibacterial agents using abundant and easily available raw material sources have been conducted. Therefore, this study aimed to acquire semiconducting nanoparticle material derived from purebred chicken eggshell waste that could effectively function as an antibacterial agent. The waste treatment was carried out using a top-down method applying the thermal decomposition method with calcination temperatures of 700 and 800 ºC for 30 hours. XRD analysis results showed CaO as a major phase and this was further supported by Rietveld calculation. The size of the crystalline phases obtained ranged from 10–45 nm, while FTIR analysis showed the appearance of CaO bond at a wave number of 715.65 cm-1. Furthermore, SEM analysis showed a rough folded particle surface with a pore percentage of 48.20%. Based on the UV-Vis DRS analysis results, chicken eggshell powder had band gap energy characteristics of 2.07, 2.74, 3.71, and 5.96 eV for sample B, as well as 4.60 and 5.82 eV for sample C. Activation of purebred chicken eggshell powder as antibacterial was performed both qualitatively and quantitatively using photocatalytic and non-photocatalytic methods. Qualitatively, both samples showed antibacterial activity, with a minimal inhibitory concentration (MIC) of 1,000 µg/mL.