Saccharification of delignified sawdust from 20 different trees in the Lagos area of Nigeria

Sawdust produced during the chopping of trees is a major waste product causing pollution of air as well as of the Lagos Lagoon in Nigeria. Sawdust from 20 different trees processed in the wood industry has been delignified successively by the Kraft process and hydrogen peroxide followed by Trichoderma viride cellulose catalyzed bioconversion into glucose, a fermentable sugar. Sugars are also released from sawdust during each delignification procedure prior to enzymatic catalyzed bioconversion. A 654% increase in sugar formation was observed from Entada gigas and 422% increase from Nauclea diderrichii when exposed to both delignification procedures compared to the amount of sugar released during Kraft pretreatment only. Relative high amounts of glucose were released during bioconversion of these waste celluloses when subjected to both delignification procedures compared to the bioconversion of Kraft delignified sawdust. Both delignification procedures resulted in a 175% increase in sugar formation for both Erythrophleum suaveolens and Milicia excels wood species. Different glucose concentrations were released during biodegradation with the highest at 9.23 mg.ml-1 released from Lophira alata after Kraft pretreatment and 14.28 mg.ml-1 from E. suaveolens after both delignification procedures. The concentration of sugar produced during the cellulase catalyzed bioconversion of delignified sawdust was many folds higher than the amount of sugars released during the delignification procedures.Key words: Bioenergy, sawdust, Trichoderma viride cellulase, delignification, saccharification

Development of sawdust from the Lagos Lagoon in Nigeria as a renewable feedstock for bio-product development

The accumulation of solid waste and consumption of fossil fuels are two phenomenons which already have a major destructive effect on the environment. The lack of alternative solid waste management procedures and shortage of the development of renewable energy resources should be addressed in order to sustain environmental quality. Sawdust is a major waste product along the Lagos lagoon with cellulose one of the predominant structural components of sawdust. The bio-conversion of waste cellulose, a glucose biopolymer into glucose a fermentable sugar has been performed with cellulase from Aspergillus Niger. Delignified and non-delignified sawdust from five different trees along the Lagos Lagoon have been saccharified with A. niger cellulase. The saccharification of these sawdust materials have been performed at different incubation temperatures of 30°C, 40°C, 50°C and 60°C. Optimum saccharification of non-delignified and delignified cellulose from the various trees along the Lagos Lagoon were optimum saccharified at different temperatures resulting in different sugar concentrations produced. A temperature of 40°C was optimum for maximum degradation of non-delignified cellulose from all the trees producing sugar at concentration between 3.0 – 4.3mg.ml-1. Optimum saccharification of delignified cellulose from all the trees was obtained at a temperature of 50°C resulting in a sugar concentration of 5.9 – 8.4mg.ml-1

The bryofloristic elements of southern Africa

A TWINSPAN classification divides the moss flora of southern Africa (South Africa, Namibia, Botswana, Swaziland, and Lesotho) into two main bryofloristic elements: (1) the Xerophytic (south-western) element mainly distributed in the winter rainfall and semi-arid to arid, temperate areas of southern Africa, and (2) the Mesophytic (subtropical) element distributed in more stable, subtropical habitats of the northern, eastern and southern parts of southern Africa. The Xerophytic element is dominated by acrocarpous mosses, including the ephemerals, while the Mesophytic element contains most of the pleurocarpous mosses. The main Xerophytic element is subdivided into the Eastern Highlands and Cape Elements while the Mesophytic element consists of the Afromontane Grassland and Afromontane Forest Elements. The Afromontane Forest Element is the largest bryofloristic element and contains the most southern African moss endemics. The four bryofloristic elements are subdivided into eight subelements: the Eastern Highlands Element into the Mont Aux Sources and Widespread Subelements, the Cape Element into the West Coast and Boland Subelements, the Afromontane Grassland Element into the Disjunct Cape Peninsula and Drakensberg Subelements, and the Afromontane Forest Element into the Widespread Afromontane and Tropical Afromontane Subelements. Many of the bryofloristic elements and distribution centres correspond with phytogeographical elements and centres described for the seed plants of southern Africa. The Afromontane area in the south-western Cape is identified as a bryogeographical hotspot