The Relationship of Fiber Cell Wall Ultrastructure to Soft Rot Decay in Kempas (Koompassia malaccensis) Heartwood

The ultrastructure of fiber walls in kempas (koompassia malaccensis) heartwood was examined in relation to soft rot cavity formation. The fibers consisted of middle lamella and thick secondary wall. The secondary wall was differentiated in to a S1 layer, and a unique multi-lamellar S2 layer. Two distinct forms of lamellae were recognisable, one type being considerably thicker than the other. They also differed in their electron density, the thin lamellae being much denser than the thick lamellae. It was not possible to determine whether a S3 layer also existed, because of the presence of a dense material coating the lumen wall, which obscured the definition of this region of the fiber wall. The resistance to soft rot varied with different regions of the fiber wall, middle lamella being completely resistant and the thick S2 lamellae least resistant. The observed relationship between the ultrastructure of these fiber wall regions and the degree of their resistance/susceptibility to soft rot cavity formation is discussed

Resistance of the S1 layer in kempas heartwood fibers to soft rot decay

Naturally durable heartwoods, where available, continue to be used as support structures in environments considered hazardous, particularly in ground contact. However, durability of heartwoods against wood decay microorganisms varies. Therefore, it is important to evaluate heartwood products for their in-service performance in order to maximise benefits derived from this valuable natural resource of limited supply. In the work presented, wood pieces from a kempas (Koompassia malaccensis) utility pole that had been placed in service in an acidic soil in Malaysia, and in time had softened at the ground-line position, were examined by light and transmission electron microscopy to evaluate the cause of deterioration. Light microscopy (LM) provided evidence of extensive attack on fibre cell walls by cavity-producing soft rot fungi. Transmission electron microscopy (TEM) revealed in greater detail the distribution and micromorphologies of cavities as well as their relationships to the fine structure of fibre cell walls, which consisted of a highly electron dense middle lamella, a moderately dense S1 layer and a multilamellar S2 layer with variable densities, reflecting differences in lignin concentration. The resistance of the moderately dense S1 layer to soft rot was a feature of particular interest and is the main focus of the work presented. The resistance appeared to be correlated with high lignification of the outermost region of the S2 wall, interfacing with the S1 layer, an unusual cell wall feature not previously described for normal wood. © 2018 International Association of Wood Anatomists, Published by Koninklijke Brill NV, Leiden

Soft rot decay of Cengal (Neobalanocarpus heimii) heartwood in ground contact in relation to extractive microdistribution

The heartwood of cengal (Neobalanocarpus heimii, fam. Dipterocarpaceae)is naturally durable. A square-sawn utility pole specimen of cengal heartwood, after 30 years in ground contact, showed 10-15 mm surface decay all around the ground line position, accompanied with isolated surface termite attack at the decayed region. Light and transmission electron microscopy (TEM) of the decayed regions provided evidence of wood cell wall degradation by cavity-forming soft rot fungi. In the outermost layers, where such decay was most severe and severely discolored, all tissue types were degraded. However, in regions with moderate decay, differences in tissue types were observable in the extent of cell wall degradation. The presence of relatively intact vessels and parenchyma cells among heavily degraded fibres suggested that fibres were more susceptible to decay than vessels and parenchyma. Middle lamella was the only cell wall region which remained intact in all cell types which were severely degraded

Modification of overlap extension PCR: A mutagenic approach

183-186In vitro site-directed repair or creation of a mutation is an invaluable technique in genetic and protein engineering. Several methods have appeared in literature but still require many modifications. We describe a rapid and efficient modified overlap extension PCR method for multiple uses in mutagenesis studies. The protocol is based on two rounds of PCR with the help of two sets of primers, two flanking and two internal mutagenic primers. Two fragments of DNA prepared in first round of PCR are then allowed themselves to anneal in the second stage of PCR using gradient annealing temperature without using flanking primers. This protocol has been used for correcting a mutation caused in exoglucanase (CBHII) gene of Trichoderma spp. We successfully synthesized the full length of gene from two fragments in the second round of PCR in lesser time.</b

Evaluation of biomass quality in short-rotation bamboo (Phyllostachys pubescens) for bioenergy products

Abstract Background In order to improve the availability of biomass, the concept of growing high yield biomass with short rotations and intensive culture has been introduced. Bamboo has become a feedstock of potential interest for future energy production due to its high productivity and short rotation time. The growth age of biomass is an important factor affecting the efficiency of bioconversion and pretreatment for bioenergy production. In this regard, more information is required on the morphology and chemical composition of bamboo for short-rotation biomass production. In this study, we used a compositional assay to compare a bamboo of two different growth ages. Results Bamboo of two different ages showed characteristics patterns of morphology, chemical composition, and bioconversion. In young-age (2-month-old) bamboo, the pattern of tissue organization was similar to that of old-age (3-year-old) bamboo, indicating that the former had reached its full height. There were significant differences between young-age and old-age bamboo in terms of chemical composition. The glucose contents in old-age bamboo did not differ significantly among its internodes. For young-age bamboo, the lignin contents were 14.6–18.3%, whereas those of old-age bamboo were considerably higher, ranging from 25.4 to 27.1% with increasing syringyl-to-guaiacyl ratio. The yield of total sugars following enzymatic hydrolysis of young-age bamboo was approximately eight times. However, following hydrogen peroxide–acetic acid pretreatment, the results of separate hydrolysis and fermentation and simultaneous saccharification and fermentation did not differ significantly between young- and old-age bamboo. However, ethanol production was higher in 2-month old than in 3-year old from initial raw biomass. Conclusion Our data show that the production of total sugar from raw material was high in young bamboo with low lignin content. With respect to short-rotation biomass, bamboo culm harvested after termination of height growth is more appropriate for use as a biomass resource to achieve a high yield for bioconversion process

Effect of Cation Influx on the Viability of Freeze-Dried <em>Lactobacillus brevis</em> WiKim0069

Extension of the storage stability of freeze-dried lactic acid bacteria is important for industrialization. In this study, the effect of cation influx from soy powder, which contains high amounts of cations, as a cryoprotective agent on the viability of freeze-dried Lactobacillus brevis WiKim0069 was tested. Compared to that in the absence of the soy powder, bacterial viability was significantly higher in the presence of soy powder. Approximately 4.7% of L. brevis WiKim0069 survived in the absence of the protective agent, whereas 92.8% viability was observed in the presence of soy powder. However, when cations were removed from the soy powder by using ethylenediaminetetraacetic acid (EDTA) and a cationic resin filter, the viability of L. brevis WiKim0069 decreased to 22.9–24.7%. When the soy powder was treated with ethylene glycol tetraacetic acid, the viability was higher than when it was pretreated with EDTA and a cationic resin filter, suggesting that Mg2+ had a role in enhancing the viability of L. brevis WiKim0069. Cold adaptation at 10 °C prior to freeze-drying had a positive effect on the storage stability of freeze-dried L. brevis WiKim0069, with 60.6% viability after 56 days of storage. A decrease in the fluorescence polarization value indicated an increase in membrane fluidity, which regulates the activity of ion channels present in the cell membrane. Cold adaptation caused activation of the cation channels, resulting in increased intracellular influx of cations, i.e., Ca2+ and Mg2+. These results suggest that cold adaptation can be used to improve the storage stability of L. brevis WiKim0069