Kandasamy Saravanakumar

Cellulase from Trichoderma harzianum interacts with roots and triggers induced systemic resistance to foliar disease in maize.

Trichoderma harzianum is well known to exhibit induced systemic resistance (ISR) to Curvularia leaf spot. We previously reported that a C6 zinc finger protein (Thc6) is responsible for a major contribution to the ISR to the leaf disease, but the types of effectors and the signals mediated by Thc6 from Trichoderma are unclear. In this work, we demonstrated that two hydrolases, Thph1 and Thph2, from T. harzianum were regulated by Thc6. Furthermore, an electrophoretic mobility shift assay (EMSA) study revealed that Thc6 regulated mRNA expression by binding to GGCTAA and GGCTAAA in the promoters of the Thph1 and Thph2 genes, respectively. Moreover, the Thph1 and Thph2 proteins triggered the transient production of reactive oxygen species (ROS) and elevated the free cytosolic calcium levels in maize leaf. Furthermore, the genes related to the jasmonate/ethylene signaling pathway were up-regulated in the wild-type maize strain. However, the ΔThph1- or ΔThph2-deletion mutants could not activate the immune defense-related genes in maize to protect against leaf disease. Therefore, we conclude that functional Thph1 and Thph2 may be required in T. harzianum to activate ISR in maize.

Biosorption of chromium by mangrove-derived Aplanochytrium sp.

The microbial dried biomass of Thraustochytrids is used as bioadsorbent for the removal of the chromium in aqueous solution. In this investigation, three species of Thraustochydrids namely Aplanochytrium sp., Thraustochytrium sp. and Schizochytrium sp. were tested for the efficiency of chromium accumulation by culturing in chromium-incorporated medium at 30°C for one week incubation. The biomass was harvested by filtration through Whatman no.1 filter paper. The level of metal accumulation in the biomass was determined by using an inductively coupled plasma system (ICP- Optical Emission Spectrophotometer; Optima 2100DV). Finally, among the three strains, Aplanochytrium spp. was selected for the adsorption kinetics and optimization using response surface methodology. Optimization of chromium removal by dried microbial biomass was analyzed with important factors of different pH, adsorbent dosage (Aplanochytrium dried biomass), temperature and processing time with 30 batch experimental plan derived from the centre composite design (CCD) of response surface methodology. Aplanochytrium sp . dried biomass removed chromium of 69.4% in aqueous solution. Therefore, Aplanochytrium sp. dried biomass is potent for the removal of chromium in waste water treatment. Key words: Mangroves, chromium removal, Aplanochytrium sp., biosorption, waste water treatment.

Effect of Trichoderma harzianum on maize rhizosphere microbiome and biocontrol of Fusarium Stalk rot

Fusarium stalk rot (FSR) caused by Fusarium graminearum (FG) significantly affects the productivity of maize grain crops. Application of agrochemicals to control the disease is harmful to environment. In this regard, use of biocontrol agent (BCA) is an alternative to agrochemicals. Although Trichoderma species are known as BCA, the selection of host-pathogen specific Trichoderma is essential for the successful field application. Hence, we screened a total of 100 Trichoderma isolates against FG, selected Trichoderma harzianum (CCTCC-RW0024) for greenhouse experiments and studied its effect on changes of maize rhizosphere microbiome and biocontrol of FSR. The strain CCTCC-RW0024 displayed high antagonistic activity (96.30%), disease reduction (86.66%), biocontrol-related enzyme and gene expression. The root colonization of the strain was confirmed by eGFP tagging and qRT-PCR analysis. Pyrosequencing revealed that exogenous inoculation of the strain in maize rhizosphere increased the plant growth promoting acidobacteria (18.4%), decreased 66% of FG, and also increased the plant growth. In addition, metabolites of this strain could interact with pathogenicity related transcriptional cofactor FgSWi6, thereby contributing to its inhibition. It is concluded that T. harzianum strain CCTCC-RW0024 is a potential BCA against FSR.

Bio removal of malachite green by mangrove-derived Aplanochytrium sp., KGA2512

Effect of mangrove-derived Aplanochytrium sp., was studied for the removal of malachite green in aqueous solution under controlled experimental conditions. The dye removal was measured at regular interval by measuring its color intensity. This was confirmed further by Fourier Transform Infra Red (FTIR) and also to find out the change in the chemical groups. To enhance the dye removal, a statistical optimization was done by two phases of response surface methodology (RSM): (i) Plackett-Burman design for selection of the important process enhancing factors of dye removal, such as pH, temperature, incubation period, dye concentration, glucose, peptone and yeast extract and (ii) Centre composite design to study optimized condition, interaction and combined effect of the selected factors on dye removal. Aplanochytrium sp., was found to remove the azo-dye significantly up to 86.32% within five and half days of incubation under optimized conditions of pH 7.8 and at temperature of 27.8°C. This study proved that mangrove-derived Aplanochytrium sp., was found promising for its potential of synthetic dye removal

Biodiversity of Trichoderma Community in the Tidal Flats and Wetland of Southeastern China

To investigate the biodiversity of Trichoderma (Hypocreaceae) and their relation to sediment physical and chemical properties, we collected a total of 491 sediment samples from coastal wetlands (tidal flat and wetland) in Southeast China. Further, we applied two types of molecular approaches such as culture dependent and independent methods for identification of Trichoderma spp. A total of 254 isolates were obtained and identified to 13 species such as T. aureoviride, T. asperellum, T. harzianum, T. atroviride, T. koningiopsis, T. longibrachiatum, T. koningii. T. tawa, T. viridescens, T. virens, T. hamatum, T. viride, and T. velutinum by the culture-dependent (CD) method of these, T. tawa was newly described in China. Subsequently, the culture indepented method of 454 pyrosequencing analysis revealed a total of six species such as T. citrinoviride, T. virens, T. polysporum, T. harzianum/Hypocrea lixii and two unknown species. Notably, T. citrinoviride and T. polysporum were not found by the CD method. Therefore, this work revealed that the combination of these two methods could show the higher biodiversity of Trichoderma spp., than either of this method alone. Among the sampling sites, Hangzhou, Zhejiang Province, exhibited rich biodiversity and low in Fengxian. Correlation and Redundancy discriminant analysis (RDA) revealed that sediment properties of temperature, redox potential (Eh) and pH significantly influenced the biodiversity of Trichoderma spp.

Adenosine deaminase production by an endophytic bacterium (Lysinibacillus sp.) from Avicennia marina

The present study was carried out with the following objectives: (1) to isolate the endophytic bacilli strains from the leaves of mangrove plant Avicennia marina, (2) to screen the potential strains for the production of adenosine deaminase, (3) to statistically optimize the factors that influence the enzyme activity in the potent strain, and (4) to identify the potent strain using 16S rRNA sequence and construct its phylogenetic tree. The bacterial strains isolated from the fresh leaves of a mangrove A. marina were assessed for adenosine deaminase activity by plating method. Optimization of reaction process was carried out using response surface methodology of central composite design. The potent strain was identified based on 16S rRNA sequencing and phylogeny. Of five endophytic strains, EMLK1 showed a significant deaminase activity over other four strains. The conditions for maximum activity of the isolated adenosine deaminase are described. The potent strain EMLK1 was identified as Lysinibacillus sp. (JQ710723) being the first report as a mangrove endophyte. Mangrove-derived endophytic bacillus strain Lysinibacillus sp. EMLK1 is proved to be a promising source for the production of adenosine deaminase and this enzyme deserves further studies for purification and its application in disease diagnosis.

Green synthesis and characterization of biologically active nanosilver from seed extract of Gardenia jasminoides Ellis

This article reports the utilization of seed extract (GSE) from Gardenia jasminoides Ellis. in the synthesis of silver nanoparticles (Gs-AgNPs) with versatile biological activities. The synthesized Gs-AgNPs were spherical in shape, crystal lattice with an average size of 20 nm as confirmed by UV-vis spectrum, X-ray diffractometer (XRD), Transmission electron microscopy with Energy dispersive X-ray spectroscopy (TEM-EDS) and particle size analyses (PSA). Phenolic compounds, proteins, and terpenoids were likely involved in the Gs-AgNPs synthesis, as indicated by Fourier-transform infrared spectroscopy (FTIR) analysis. The minimum bactericidal concentration (MBC) of the Gs-AgNPs was 12.5 μg·ml-1 for S. enterica Typhimurium and 10 μg·ml-1 for S. aureus. The MBC of the Gs-AgNPs induced >70% bacterial cell death within 60 min, as confirmed by growth curve analysis followed by Confocal laser scanning microscope (CLSM). Gs-AgNPs showed the highest scavenging activity for 1, 2-diphenyl-1-picrylhydrazyl DPPH radical (92.3 ± 0.86%), Nitric oxide (NO) radical (72.5 ± 2.15%), and Hydrogen peroxide H2O2 radical (85.25 ± 1.45%). Anticancer results revealed an IC50 of 15.625 ± 1.3 μg·ml-1 for Gs-AgNPs, whereas it was 580.54 ± 2.5 μg·ml-1 for GSE. The Gs-AgNPs generated high reactive oxygen species (ROS) resulting in induced apoptosis as evident by up-regulation of apoptosis-related protein. In addition, the photocatalytic results revealed about 92% of the reduction in Coomassie Brilliant Blue dye color with Gs-AgNPs. Hence, this work provided economically viable and ecologically sustainable Gs-AgNPs as an alternative biomaterial for future therapeutic applications as antimicrobial, antioxidant, anti-cancer agents and in dye degradation for water remediation.

Impact of mangrove vegetation on seasonal carbon burial and other sediment characteristics in the Vellar-Coleroon estuary, India

This work quantified the total carbon and 12 other sediment characteristics at 10 soil depths, in planted and or natural mangrove forests in comparison with non-vegetated soil for four seasons of the year 2009–2010 in the Vellar-Coleroon estuarine complex, India. The sediment characteristics varied significantly between mangrove-vegetated and non-vegetated habitats or seasons of analysis, but not between soil depths. The mangrove sediments were rich in total carbon and total organic carbon as compared to non-mangrove sediments (p <0.01). Total carbon was 98.2% higher in mature mangroves and 41.8% in planted mangroves than that in non-mangrove soil. Total organic carbon was as much as 2.5 times greater in mature mangroves and 2 times greater in planted mangroves than that in unvegetated soil. Carbon contents also varied many fold by season. Total carbon content was 8.6 times greater during pre-monsoon, 4.1 times greater during post-monsoon and 2.5 times greater during monsoon than during summer (p<0.01 in all cases). Similarly, total organic carbon was 5.9 times greater during pre-monsoon, 3.1 times greater during post-monsoon and 69% greater during monsoon than during summer. In general, higher levels of sediment carbon were recorded during pre and post-monsoon seasons than during other seasons. Total carbon concentration was correlated negatively to temperature, sand and phosphorus (p <0.01); positively correlated with redox potential, silt, clay, C/N ratio, potassium (p <0.01) and nitrogen (p <0.05); but not correlated with soil depth, pH or salinity. This work revealed that the carbon burial was rapid at the annual rate of 2.8% for total carbon, and 6.7% for total organic carbon in mangrove-planted sediment. Clearing of mangroves can result in significantly and rapidly reduced carbon stores. Our study highlights the importance of natural and plantation mangrove stands for conserving sediment carbon in the tropical coastal domain.

Novel metabolites from Trichoderma atroviride against human prostate cancer cells and their inhibitory effect on Helicobacter pylori and Shigella toxin producing Escherichia coli

The present study aimed to purify and identify the metabolites from T. atroviride using high-performance liquid chromatography (HPLC) and 1H and 13C nuclear magnetic resonance spectrometer (NMR) followed by analyzing their toxicological, antibacterial and anticancer properties. This work identified two metabolites - TM1 and TM2. TM1 was in two forms: (i) 1, 3-dione-5, 5-dimethylcyclohexane; and, (ii) 2-enone-3hydroxy -5,5-dimethylcylohex, while TM2 was 4H-1,3-dioxin-4-one-2,3,6-trimethyl. These metabolites did not exhibit any irritant or allergic reaction as revealed by HET- CAM test. TM2 significantly inhibited the growth of H. pylori and Shigella toxin producing Escherichia coli (STEC) as evident by in vitro and microscopic observations of bacterial cell death. TM2 also induced the cell death and cytotoxicity, as revealed by cell viability test and western blot analysis. According to microscopic, flow cytometer and western blot analysis, TM2 treated cells displayed higher ROS, cell death, and apoptosis-related protein expression than TM1 and control. This study concluded that TM2 derived from T. atroviride was a potential therapeutic agent for anti-prostate cancer and antibiotic agent against MDR- H. pylori and STEC and it is also recommended to carry out further in vivo animal model experiments with improved stability of the metabolites for future pharmaceutical trails.

Preservative effect of Chinese cabbage (Brassica rapa subsp. pekinensis) extract on their molecular docking, antioxidant and antimicrobial properties

This study aimed at investigating the antimicrobial activity of different solvent extracts of Chinese cabbage Brassica rapa subsp. pekinensis (BRARP) and their antioxidant and cytotoxicity properties. Of the different solvents extracts, the chloroform extracts (CE) were significantly inhibited the bacterial pathogens at minimum inhibitory concentration (MIC) of 16.5 mg.mL-1. Biochemical analysis revealed that total phenol (62.6 ± 0.05 mg GAE.g-1) and flavonoids (27.6 ± 0.04 mg QE.g-1) were higher in the extracts of BRARP, which resulted in enhanced antioxidant activity in CE. A total of eight dominant compounds were detected in the potent antimicrobial extract from BRARP based on GC-MS analysis. The molecular interactions study revealed that, among the screened compounds the 1,2-benzenedicarboxylic acid and 2,3-dicyanopropionamide interacted with the active site of pathogenicity and survival related protein with lipopolysaccharide (LpxC) with higer binding energy. This work concluded that the 1, 2-Benzenedicarboxylic acid and 2, 3-Dicyanopropionamide from BRARP was reported to be good non-cytotoxic and antioxidant antimicrobials against bacterial pathogens.