South Asian Journal of Experimental Biology

Screening and isolation of Bacillus isolates for Levansucrase activity and for Levan Production

D.Srilatha — 2025-04-01

Levan, a fructan homoexopolysaccharide synthesized from sucrose, has gained significant industrial interest due to its antilipidemic, anticancer, and prebiotic properties. This study aimed to isolate and characterize high-yielding levan-producing Bacillus strains from diverse natural sources, including fermented foods, decayed fruits, sugarcane juice, and sugarcane field soils. Using sucrose-enriched media, ten Bacillus isolates were obtained, of which seven exhibited high viscosity and mucoid colony morphology on Cortezi medium, indicative of exopolysaccharide production. Among them, a single strain, Bacillus velezensis SR1, demonstrated the highest levansucrase activity (2.5 U/ml) and levan yield (1.2 g/ml) under submerged fermentation at 37°C and pH 6.5. Enzyme activity peaked at 48 hours before declining due to nutrient depletion. Structural characterization of the extracted levan using Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of β-(2,6) glycosidic linkages with β-(1,2) branching, essential for its functional properties, revealing the spectral peaks observed at 3297 cm⁻¹, 1125 cm⁻¹, 1012 cm⁻¹, and 925 cm⁻¹, corresponding to O−H groups in fructose, C−O−H stretching, C−O−C stretching vibrations, and pyranose ring structures, respectively. Molecular identification via 16S rDNA sequencing revealed 99% similarity to Bacillus velezensis SR1, confirming its taxonomic identity. These findings highlight Bacillus velezensis SR1 as a promising strain for industrial levan production, offering potential applications in food, pharmaceutical, and biotechnological sectors.

Influence of solvents on antibacterial activity of leaves and bark of Neolamarckia cadamba: A preliminary study

Swati Shikha — 2025-04-01

The rise of antibacterial resistance has entailed the exploration of antibacterial agents. Various solvents have been administered to extract antibacterial agents from plants. However, the extracting efficacy of solvents vary significantly. Choosing a solvent is crucial as it influence factors like reaction, stability and efficacy. The present study aimed to investigate the impact of different solvents (Ethanol, Methanol, Acetone, Benzene, DMSO and Aqueous) on the antibacterial activity of Neolamarckia cadamba extracts against Bacillus subtilis and Pseudomonas aeruginosa. The antibacterial activity was conducted by impregnating the disc with different solvent extracts of Neolamarckia cadamba on agar plates inoculated with test pathogens. After incubation, the zone of inhibition around the impregnated discs was measured (mm). Leaf (methanol) and bark (ethanol) extract demonstrated the highest zone of inhibition of 16 mm and 14.1 mm. All solvent extracts exhibited antibacterial activity except, aqueous which showed no significant antibacterial effect. Methanol and ethanol showed the highest antibacterial activity followed by acetone, benzene, DMSO and aqueous. The result of this study suggests that choice of solvent plays a crucial role in extraction of antibacterial agents and also highlights the significance of solvent selection in optimizing the impact on their subsequent activity.

Accumulation of Total Heterotrophic Bacteria and E. coli in Villorita cyprinoides in the Anchuthengu-Akathumuri Backwaters, Southern Kerala, India

Rakhi. R — 2025-04-01

The Anchuthengu-Akathumuri backwater system in Kerala, India, is vital for local livelihoods but faces increasing pressures from tourism and urban development, threatening water and sediment quality. This study assesses microbial contamination in water, sediment, and the bivalve Villorita cyprinoides over a year (February 2022 to March 2023) at five sampling stations with varying levels of human influence. The study employed a combination of field and laboratory methodologies, including monthly sampling of water and sediment from five stations, followed by microbiological analysis using standard plate count and most probable number (MPN) techniques. Physicochemical parameters, such as water temperature, pH, conductivity, salinity, dissolved oxygen (DO), and biochemical oxygen demand (BOD), were also analyzed. The results showed that the annual mean log values of TPC in water, sediment, and V. cyprinoides samples were 5.35±0.34, 7.55±0.31, and 7.73±0.30 log10cfu/ml, respectively. E. coli levels in water, sediment, and V. cyprinoides samples ranged from 1.03±0.32 to 1.58±0.56 log10 MPN. Seasonal variations revealed higher TPC levels during pre-monsoon (PRM) with 5.38±0.22 log10cfu/ml in water and 7.41±0.25 log10cfu/g in sediment. Physicochemical parameters showed significant variations, with water temperature ranging from 27.6±2.45°C (post-monsoon) to 30.5±3.8°C (PRM). pH levels ranged from 7.18±0.14 to 7.56±0.06, while conductivity varied from 5.67±2.36 to 13.97±1.4 mS/cm. Correlation analysis revealed significant relationships between physicochemical and microbiological parameters, highlighting the importance of considering both aspects in water quality assessments. Additonally, bioaccumulation study revealed higher microbial concentrations in Villorita cyprinoides compared to surrounding water and sediment, raising food safety concerns. The findings emphasize the need for ongoing monitoring and management of microbial contamination to protect public health and ecosystem integrity. Recommended strategies include reducing anthropogenic impacts, improving waste management, and promoting sustainable development practices. This research offers valuable insights into microbial pollution dynamics, guiding targeted interventions for sustainable coastal management and community health protection.

Green Synthesis and Characterization of Silver Nanoparticle Using Methanolic Extract of Ventilago madraspatana Gaertn. Leaves

Sathiya V — 2025-04-01

A growing number of researchers are exploring the eco-friendly production of silver nanoparticles (AgNPs) and their potential uses, particularly in targeted tissue therapy. This study aims to produce and analyze AgNPs derived from the leaves of Ventilago madraspatana, using a green synthesis method. Silver nitrate was dissolved in deionized water to obtain a 1 mM solution of AgNO3, and the methanolic crude extract was mixed with the silver nitrate solution under specific conditions. The formation of silver nanoparticles was confirmed by the appearance of a yellowish-brown color. The synthesized silver nanoparticles were comprehensively characterized to elucidate their properties using a range of techniques, including UV-Vis spectroscopy, FTIR, XRD, SEM and TEM. A strong, shiftless absorption band was observed at 420 nm via UV-Vis spectroscopy, attributable to the surface plasmon resonance of AgNPs, confirming the successful synthesis of nanoparticles. FTIR spectroscopy revealed significant bands corresponding to functional groups. The morphology of the synthesized nanoparticles was characterized using SEM and the nanoparticles were found to be spherical, with a size range of 78-92 nm. This was confirmed by TEM, which showed that the nanoparticles were predominantly spherical, with a size range of 51 nm at 50 kx magnification. XRD analysis confirmed the crystalline structure of the synthesized silver nanoparticles. This study demonstrates the successful synthesis of silver nanoparticles using the methanolic extract of V. madraspatana and determination of their structure, providing a basis for their use in a wide range of biomedical and industrial field.

Molecular Docking of Linderniaceae Phytochemicals: Aloesin as a lead Glyoxalase I Inhibitor

Sreelakshmi T — 2025-04-01

Environmental stresses such as drought and salinity significantly affect plant survival, necessitating adaptive mechanisms for stress tolerance. Glyoxalase I (GLO1) a key enzyme in the glyoxalase system, plays a crucial role in detoxifying methylglyoxal, a cytotoxic by-product of glycolysis, thereby mitigating oxidative stress. The Linderniaceae family, known for its desiccation-tolerant species, harbours bioactive compounds with potential stress-mitigating properties. However, their interaction with GLO1 remains unexplored. The study aimed to evaluate the phytochemical composition of Linderniaceae weeds using LCMS profiling and investigate the molecular interaction of key phytocompounds with GLO1 through docking analysis to assess their role in stress adaptation. LCMS analysis of ethanol extracts in positive ion mode revealed Aloesin, Isovitexin, and Kaempferol-3-O-glucoside, which were subjected to molecular docking using Auto Dock Tools. The binding affinities and hydrogen bond interaction were analysed to determine their inhibitory potential. Docking results revealed Aloesin (-7.36 kcal/mol, Ki=4.04μM) as the most potent GLO1 inhibitor, forming strong hydrogen bonds with Arg122, Asp120, Ser113, and Thr111. Isovitexin and Kaempferol-3-O glucoside also exhibited moderate binding affinities, suggesting their role in stress adaptation. These findings provide novel insights into the desiccation resilience of Linderniaceae weeds. By integrating LCMS phytochemical profiling with docking studies, this research highlights potential of Linderniaceae derived phytochemicals in plants stress resilience, paving way for future application in sustainable agricultural and crop improvement.