Sustainable phyto-fabrication of silver nanoparticles using Gmelina arborea exhibit antimicrobial and biofilm inhibition activity

Increase in bacterial resistance to commonly used antibiotics is a major public health concern generating interest in novel antibacterial treatments. Aim of this scientific endeavor was to find an alternative efficient antibacterial agent from non-conventional plant source for human health applications. We used an eco-friendly approach for phyto-fabrication of silver nanoparticles (AgNPs) by utilizing logging residue from timber trees Gmelina arborea (GA). GC–MS analysis of leaves, barks, flowers, fruits, and roots was conducted to determine the bioactive compounds. Biosynthesis, morphological and structural characterization of GA-AgNPs were undertaken by UV–Vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). GA-AgNPs were evaluated for antibacterial, antibiofilm, antioxidant, wound healing properties and their toxicity studies were carried out. Results identified the presence of terpenoids, sterols, aliphatic alcohols, aldehydes, and flavonoids in leaves, making leaf extract the ideal choice for phyto-fabrication of silver nanoparticles. The synthesis of GA-AgNPs was confirmed by dark brown colored colloidal solution and spectral absorption peak at 420 nm. Spherical, uniformly dispersed, crystalline GA-AgNPs were 34–40 nm in diameter and stable in solutions at room temperature. Functional groups attributed to the presence of flavonoids, terpenoids, and phenols that acted as reducing and capping agents. Antibacterial potency was confirmed against pathogenic bacteria Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus by disc diffusion assay, MIC and MBC assay, biofilm inhibition assay, electron-microscopy, cell staining and colony counting techniques. The results from zone of inhibition, number of ruptured cells and dead-cell-count analysis confirmed that GA-AgNPs were more effective than GA-extract and their bacteria inhibition activity level increased further when loaded on hydrogel as GA-AgNPs-PF127, making it a novel distinguishing feature. Antioxidant activity was confirmed by the free radical scavenging assays (DPPH and ABTS). Wound healing potential was confirmed by cell scratch assay in human dermal fibroblast cell lines. Cell-proliferation study in human chang liver cell lines and optical microscopic observations confirmed non-toxicity of GA-AgNPs at low doses. Our study concluded that biosynthesized GA-AgNPs had enhanced antibacterial, antibiofilm, antioxidant, and wound healing properties.

SUSTRATOS CON ASERRÍN DE CONÍFERAS Y LATIFOLIADAS PARA PRODUCIR PLANTA DE Pinus patula Schiede ex Schltdl. et Cham.

Desde el año 2003 en algunos viveros forestales del país se utilizan sustratos con aserrín fresco de pino y oyamel. Debido a la disponibilidad de aserrín de una variedad mayor de especies, este estudio planteó la hipótesis de que los sustratos con aserrín fresco de latifoliadas son aptos para producir planta de Pinus patula con calidad similar a la que se produce en sustratos con aserrín de especies de pino u oyamel. Para probarla, el objetivo fue evaluar el crecimiento de plantas de P. patula en charolas de poliestireno llenas con sustratos con 60% de aserrín fresco de las 11 principales especies forestales maderables (coníferas y latifoliadas) que se aprovechan en las regiones centro y sureste de México. El aserrín utilizado fue de las especies: Abies religiosa, Hevea brasiliensis, Gmelina arborea, Mangifera indica, Pinus ayacahuite, Pinus montezumae, Pinus patula, Pinus teocote, Quercus laurina, Quercus rugosa y Tectona grandis. Las charolas (77 cavidades de 170 cm3) se llenaron con mezcla de sustrato con aserrín (60%), corteza de pino compostada, perlita y vermiculita (20, 10 y 10%). A cada mezcla para rellenar charolas se adicionó fertilizante: Multicote® 18-6-12 y 12-24-12 (N-P2O5-K2O) de 8 meses de liberación (4 g L-1 de cada uno) y Micromax® (1 g L-1). El diseño experimental fue completamente al azar e incluyó 11 tratamientos y cuatro repeticiones. A los siete meses se presentaron diferencias (p≤0.05) por tratamiento en diámetro, altura, pesos secos, índices de robustez y de calidad de Dickson, y en la concentración foliar de N, K, Mg, Fe, Mn, Zn, Cu y B. Con todos los sustratos se obtuvieron índices de calidad de Dickson ≥0.47; diámetros ≥4 mm y alturas de 20 a 30 cm, excepto el de M. indica. Las concentraciones de N y P fueron ≥1.3 y 0.20%, excepto en las plantas de los sustratos H. brasiliensis y M. indica. Las concentraciones de K, Mg, Ca, Zn y B fueron inferiores a los valores recomendados en todos los tratamientos. La planta producida en el sustrato con aserrín de P. ayacahuite desarrolló las mejores variables morfológicas y de concentración de nutrientes; mientras que los valores más bajos se observaron en la planta con sustrato de M. indica. Lo cual se atribuye respectivamente, al menor y al mayor contenido de sales y fenoles en el aserrín de esas dos especies.

Intercropping Short Rotation Timber Species with Teak: Enabling Smallholder Silviculture Practices

Community forest management for timber production requires short- and long-rotation companion species to fulfill the demands of the timber industry, improve farmer welfare and maintain environmental sustainability. Four species (Falcataria moluccana, Neolamarckia cadamba, Acacia mangium and Gmelina arborea) were tested as short-rotation timber crop companion species for teak (Tectona grandis) on dry-rocky soil in the Gunungkidul community forest. The selection of short-rotation timber species was based on growth performance and survival rate at the teak site. Two years after planting, the viability of G. arborea (87.3%) and A. mangium (78.2%) was significantly (p < 0.05) higher than that of N. cadamba (40.6%) and F. moluccana (18.0%). G. arborea and N. cadamba achieved the best growth in terms of height, diameter, basal area, and volume, with the growth of A. mangium and F. moluccana being significantly inferior. Gmelina arborea has the ability to adapt to teak sites, grow well, and accompany teak. Neolamarckia cadamba demonstrated good growth with potential as a teak companion, and it demonstrated limited drought tolerance on the dry-rocky soils of the study sites. Acacia mangium had a high survival but produced slow growth, indicating that it required an advance evaluation in future years. Falcataria moluccana has different growing site requirements to teak so the performance was relatively poor at the study site. This mixed pattern provides benefits to farmers through commercial thinning of short rotations species, 5–8 years post establishment. Thinning operations will also increase the productivity of residual teak stands. The diversification of timber species in community forests can provide earlier returns, enabling the adoption of silviculture management by smallholders and communities.

Chemical Composition of Gmelina arborea: A Review

Gmelina arborea is a fast-growing tree, which grows on different localities and prefers moist fertile valleys with 750–4500 mm rainfall. It does not thrive on ill-drained soils and remains stunted on dry, sandy or poor soils; drought also reduces it to a shrubby form. The tree attains moderate to large heights of up to 30 m, with a girth of 1.2 to 4 m. It has a chlorophyll layer just under the outer bark, which is pale yellow on the outside and white inside.Gmelina arborea wood is pale yellow to cream-coloured or pinkish-buff when fresh, turning yellowish brown on exposure and is soft to moderately hard, light to moderately heavy, lustrous when fresh, usually straight to irregular or rarely wavy grained and medium course textured. Flowering takes place during February to April when the tree is more or less leafless whereas fruiting starts from May onwards up to June. The fruit is up to 2.5 cm long, smooth, dark green, turning yellow when ripe and has a fruity smell. The fruit is edible and has a bitter-sweet taste.4 This tree is commonly planted as a garden and an avenue tree; growing in villages along agricultural land and on village community lands and wastelands. It is light demander, tolerant of excessive drought, but moderately frost hardy. It has good capacity to recover from frost injury. Gamhar trees coppices very well with vigorous growth. Saplings and young plants need protection from deer and cattle. Gmelina arborea grows naturally throughout India, Myanmar, Thailand, Laos, Cambodia, Vietnam and in southern provinces of China

Effects of Strands Pre-treatment and Adhesive Type on the Properties of Oriented Strand Board Made from Gmelina (Gmelina arborea) Wood

The objective of this study was to evaluate the effects of steam treatment of strands on the physical and mechanical properties of oriented strand board (OSB) from gmelina wood (Gmelina arborea) bonded with two types of adhesive. Strands of gmelina wood were steamed at 126°C and pressure of 0.14 MPa for 1 h. OSBs were prepared with a 0.6 g/cm3 target density using two types of adhesives, namely methylene diphenyl diisocyanate (MDI) and phenol-formaldehyde (PF) resins. The resin content used was 5% for MDI and 10% for PF. The physical and mechanical properties of the OSB were evaluated referring to the JIS A 5908-2003 standard, and the values were compared with CSA 0437.0 (Grade O-1) standard. The results showed that the steam treatment improved the dimensional stability of OSB, as shown from the decrease of water absorption and thickness swelling. Steam treatment also increased the mechanical properties of the OSB, such as modulus of elasticity, modulus of rupture, internal bonding strength, and screw holding power. The results revealed that gmelina wood OSB bonded with MDI adhesives produced better OSB than bonded with PF resin. Keywords: gmelina, methylene diphenyl diisocyanate, oriented strand board, phenol-formaldehyde, steam treatment

Comparative Study of Soil Properties under Gamhar (Gmelina arborea) Based Agrisilvicultural System

A two year experiment was conducted during kharif and rabi season of 2016-2017 and 2017-2018 at experimental site near Faculty of Forestry in main campus of Birsa Agricultural University, Ranchi, Jharkhand, India. Sole cropping and gamhar based agrisilviculture systems with four different intercrops (arhar, cowpea, greengram and mustard) were under investigation. To study the overall scenario of soil properties under agrisilviculture system, soil samples were analysed at different profile depths (0-15 and 15-30 cm) to measure the changes in soil properties under the influence of gamhar (Gmelina arborea) tree and intercrops grown in between. Soil pH, electrical conductivity (dsm-1), organic carbon (%), available nitrogen, phosphorus and potassium (kg ha-1) were found higher at the soil depth 0-15 cm as compared to 15-30 cm due to addition of organic residue on the surface soil. Soil OC, available N, P and K in 0-15 cm as well as in 15-30 cm profile was found to be statistically significant. It showed an increase from initial value in all the treatments in 2016-17 and 2017-18. The increase was more in gamhar based agrisilviculture system than in sole tree and sole crops in both the years.

Monitoring transformation of two tropical lignocellulosics and their lignins after residence in Benin soils

Thermally assisted Hydrolysis and Methylation (THM), and 2D-heteronuclear single quantum coherence nuclear magnetic resonance (2D HSQC NMR) spectroscopy were used to monitor the transformation of ramial chipped wood (RCW) from Gmelina arborea and Sarcocephalus latifolius, together with their organosolv lignins, following soil incubation in Benin (West Africa). Mesh litterbags containing RCW were buried in soils (10 cm depth) and were retrieved after 0, 6, 12 and 18 months of field incubation. Chemical analysis showed that total carbohydrate content decreased, while total lignin content increased as RCW decomposition progressed. Ash and mineral content of RCW increased significantly after 18 months of decomposition in soil. Significant N-enrichment of the RCW was determined following 18 months incubation in soils, reaching 2.6 and 1.9 times the initial N-content for G. arborea and S. latifolius. Results of THM showed that the S + G sum, corresponding to lignins, increased with RCW residence time in the soils, in contrast to the response of compounds derived from carbohydrates, the sum of which decreased. Remarkably, lignin interunit linkages, most notably β-O-4′ aryl ethers, β-β′ resinol, β-5′ phenylcoumaran and p-PCA p-coumarate, survived after 18 months in the soil, despite their gradual decrease over the duration of the experiment.

Genetic variation of Gmelina arborea Roxb in Trenggalek, East Java

White teak (Gmelina arborea Roxb) is an introduced species of the verbenaceae. This study observed genetic variation of G. arborea in Trenggalek, East Java. Incomplete Block Design was used for this trial comprising four replications, five populations, 50 families, and three tree plots with planting space of 3 x 2 m. Significant differences between seed origins for height and survival rate were exhibited in this study; however, no significant differences between populations for diameter traits at 1st year old. Meanwhile, significant differences between populations for height, diameter, and survival rate existed at second years old. The mean survival rate at first and second years old were 98, 44% and 95, 95%, height were 1.23 m and 2.86 m, and stem diameter was 2.18 cm and 3.66 cm. Moderate heritability’s showed for height and diameter were (h2 i = 0.29; h2 f = 0.30), (h2 i = 0.24; h2 f = 0, 38) and (h2 i = 0.19; h2 f = 0.30), (h2 i = 0.18; h2 f = 0.28). Genetic correlation for height and diameter were rg = 0.75, and rg = 0.89. Genetic variation growth of G. arborea progeny test can be used as basic information of the plus trees selection with good performance. Therefore, the open pollination between remaining plus tress will produce a good quality of seed, which will increase the volume of timber harvested.

Glulam beams: Performance of PVA and PUR adhesives on bending strengths of locally selected Nigerian timber species

The applicability of structural timber to construction is due to its desirable qualities such as lightweight, aesthetics and eco-friendliness. However, continuous use of timber for structural purposes comes with the challenge posed by the anisotropic nature of various timber species. Advanced societies have developed and modified their sawn timber species in form of glue-laminated structural members such as beams, columns, joist etc. Nigeria timber species are yet to be fully explored along glued-laminated beams production. This paper assesses the suitability of three selected Nigerian timber species namely; Gmelina Arborea (ML), Terminalia superba (AF) and Pycnanthus angolensis (AK) for production of glued-laminated (glulam) beams. They are locally known respectively as Melina (ML), Afara (AF) and Akomu (AK). The applicability and glue-ability of the glues and their ultimate effect on the flexural strength were investigated through the use of two different types of glue components namely; polyvinyl acetate (PVA) and polyurethane (PUR) glue. The physical properties of the timber species such as moisture content (MC) and densities were determined using BS EN 408. The beams produced which are 1680mm by 150mm by 120mm in dimension were subjected to two points loading system to determine their flexural strengths and failure loads in accordance with ASTM D-198. The flexural strengths results indicated that Pycnanthus angolensis offered most resistance to bending loads with an average flexural strength value of 16.04N/mm2 when PUR glue was used and 13.04N/mm2 when PVA glue was used. The ANOVA result showed that glue types have significant effect on the flexural strength at confidence level of 95%. It was concluded that Pycnanthus angolensis is most suitable for structural applications. PUR is considered the better glue in terms of strength and glue-ability while PVA glue is considered better in terms of workability and applicability based on almost perfect glue line integrity achieved.