The heartwood of plantation-grown coast redwood trees from three forests in the North Island, New Zealand, was evaluated using in vitro decay tests with fungal cultures to determine variation in natural durability and its prediction using near infrared (NIR) spectroscopy. The NIR spectra were acquired from the solid wood surface, prior to decay testing, using a fibre-optic probe attached to a Bruker MPA FT-NIR spectrometer and an imaging spectrograph coupled to a NIR line camera. The partial least squares (PLS) regression models of mass loss with fungal decay testing, based on spectra collected with the FT-NIR spectrometer, had better predictive performance than the NIR line camera, as evidenced by fewer latent variables and slightly better R 2. The ratios of prediction to deviation (RPD) were 1.3 to 1.4 for both the spectrometer and camera system, which suggests the PLS regression models could be used to segregate the heartwood of coast redwood for high-and low values of natural durability.
Background: There is wide variation in the wood properties of plantation-grown coast redwood (Sequoia sempervirens (D.Don) Endl.) in New Zealand. Contributing factors are the seed source, silviculture, growth rate and age of the trees in the plantation forests. Little is known about how these factors affect the variation of wood properties among and within the trees of New Zealand's coast redwood forests. Methods: The wood of plantation-grown coast redwood trees from three forests in the North Island, New Zealand, was evaluated using butt log and breast height discs and cores, and in vitro decay tests with brown-and white-rot fungal cultures, to determine the variation in the heartwood content, basic density, and red colour and natural durability of the heartwood.
Aims: The aim of this study was to isolate lactic acid bacteria from chilli waste and evaluate metabolites produced for the ability to arrest wood decay.
Methods and Results: Using an optical density screening method, one bacterium (isolate C11) was identified as having pronounced antifungal properties against Oligoporus placenta. This isolate was identified as Lactobacillus brevis by 16S rRNA gene sequencing. To determine antifungal activity in wood, Pinus radiata blocks were impregnated with Lact. brevis [C11] cell‐free supernatant and exposed to brown rot fungi O. placenta, Antrodia xantha and Coniophora puteana. The treated timber demonstrated resistance to degradation from all fungi. The antifungal metabolites were heat stable and not affected by proteinase K, but were affected by neutralization with NaOH suggesting the metabolites were of an acidic nature. The presence of lactic and acetic acid was confirmed by HPLC analysis.
Conclusions: Lactobacillus brevis [C11] produced acidic metabolites that were able to inhibit the growth of wood decay fungi and subsequent wood decay.
Significance and Impact of the Study: Traditional wood treatments are becoming an environmental issue as the public demands more benign options. The use of lactic acid bacteria which are considered safe for general use is a potential alternative to the conventional heavy metal chemicals currently in use.
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