Search

Effects of pure and mixed substrates of sisal waste, grass (Panicum coloratum) and a combination of the two substrates at 50:50 (w/w) on nutritional composition, minerals and antioxidant potential of sun-dried Pleurotus sapidus 969 were investigated in the present study. To determine the proximate chemical composition and antioxidant properties of the samples, standard analytical procedures were employed. Moisture content, crude protein and crude fibre ranged between 11.09-12.80%, 6.4-6.6% and 18.3-30.5%, respectively. Macro elements Ca, Mg, Na, K, and P were also found in substantial amounts with K being present in an exceedingly higher amount (541.3-657.1 mg/100g) than the other macro minerals. The samples from the three substrates contained antioxidant β-carotene (4.6-6.0 mg/100g), lycopene (4.9-5.1mg/100g), Vitamin C (5.2-5.6 mg/100g), phenols (361.0-859.0 mg of GA/g) and flavanoids (33.5-64.0 mg RE/g).Mushroom harvested from mixed substrates contained better nutritional qualities than the pure substrate, although the phenolic content in mushrooms cultivated on sisal substrate was higher. The results further showed that, all the extracts exhibited scavenging ability and metal chelating activity. The findings showed that Pleurotus sapidus 969 is rich in nutrients, macro minerals as well as natural antioxidant which could be explored for pharmaceutical applications.

Aim of the Study : The aim of this study was to evaluate three ethanol fermentation approaches namely (I) separate hydrolysis and common fermentation (II) separate hydrolysis and fermentation and (III) simultaneous saccharification and fermentation in stirred tank reactors using inedible wild cassava as feedstock. Study Design : Tubers of wild cassava ( Manihot glaziovii) were obtained from two districts in Original Research Article

A process for the production of high bioethanol titre was established through fed-batch and simultaneous saccharification and fermentation (FB-SSF) of wild, non-edible cassava Manihot glaziovii. FB-SSF allowed fermentation of up to 390g/L of starch-derived glucose achieving high bioethanol concentration of up to 190g/L (24% v/v) with yields of around 94% of the theoretical value. The wild cassava M. glaziovii starch is hydrolysable with a low dosage of amylolytic enzymes (0.1-0.15% v/w, Termamyl® and AMG®). The Automatic Gas Potential Test System (AMPTS) was adapted to yeast ethanol fermentation and demonstrated to be an accurate, reliable and flexible device for studying the kinetics of yeast in SSF and FB-SSF. The bioethanol derived stoichiometrically from the CO2 registered in the AMPTS software correlated positively with samples analysed by HPLC (R(2)=0.99).

Aims: The aim of this study was to isolate and identify microorganisms in crude oil polluted soils in Eastern Tanzania. Study Design: Isolation and identification of microorganisms using conventional and molecular techniques.

Sisal leaf decortications residue (SLDR) is amongst the most abundant agro-industrial residues in Tanzania and is a good feedstock for biogas production. Pre-treatment of the residue prior to its anaerobic digestion (AD) was investigated using a two-stage pre-treatment approach with two fungal strains, CCHT-1 and Trichoderma reesei in succession in anaerobic batch bioreactors. AD of the pre-treated residue with CCTH-1 at 10% (wet weight inoculum/SLDR) inoculum concentration incubated for four days followed by incubation for eight days with 25% (wet weight inoculum/SLDR) of T. reesei gave a methane yield of 0.292 +/- 0.04 m(3) CH(4)/kg volatile solids (VS)(added). On reversing the pre-treatment succession of the fungal inocula using the same parameters followed by AD, methane yield decreased by about 55%. Generally, an increment in the range of 30-101% in methane yield in comparison to the un-treated SLDR was obtained. The results confirmed the potential of CCHT-1 followed by Trichoderma reesei fungi pre-treatment prior to AD to achieve significant improvement in biogas production from SLDR.

The performance of anaerobic, packed-bed bioreactors treating leachate from potato waste was evaluated in terms of organic loading rate (OLR) as well as the recirculation flow rate. Two 1 litre bioreactors, filled with porous glass beads as biofilm carriers and with continuous recirculation flow rates of 10 ml min(-1) and 20 ml min(-1) respectively, were used in the experiment. The OLR applied to each bioreactor was increased stepwise from 4 to 12 kg chemical oxygen demand (COD) m(-3)d(-1) by increasing feed flow rate. The methane yields decreased with increasing OLR in both bioreactors. The methane yield for the bioreactor with the lower recirculation flow rate ranged between 0.10 and 0.14 m3 CH4 kg COD(-1) removed, while for the other bioreactor it was 0.14-0.20 m3 CH4 kg COD(-1) removed. Both bioreactors demonstrated stable COD removal which was around 95% for the bioreactor with lower flow of recirculation while for the other it was 92%, over a range of OLRs of 4-8 kg COD m(-3)d(-1). The bioreactor with the lower recirculation flow rate showed operational stability when a high OLR, namely 12 kg COD m(-3)d(-1), was applied, while the other one became overloaded. There was an accumulation of volatile fatty acids which gave a corresponding drop in pH because the system had a low buffering capacity and this thus ultimately led to process failure. This study demonstrated the suitability of a packed bed bioreactor operated at lower recirculation flow rate for treating leachate from potato waste.

The objective of this study was to characterise and evaluate a wild inedible cassava species, Manihot glaziovii as feedstock for bioenergy production. Tubers obtained from 3 different areas in Tanzania were characterised and evaluated for bioethanol and biogas production. These bioenergy carriers were produced both separately and sequentially and their energy values evaluated based on these two approaches. Composition analysis demonstrated that M. glaziovii is a suitable feedstock for both bioethanol and biogas production. Starch content ranged from 77% to 81%, structural carbohydrates 3-16%, total crude protein ranged from 2% to 8%. Yeast fermentation achieved ethanol concentration of up to 85g/L at a fermentation efficiency of 89%. The fuel energy of the bioethanol and methane from flour-peels mix ranged from 5 to 13 and 11 to 14MJ/kgVS, respectively. Co-production of bioethanol and biogas in which the peels were added to the fermentation residue prior to anaerobic digestion produced maximum fuel energy yield of (15-23MJ/kgVS).

Co-digestion of various wastes has been shown to improve the digestibility of the materials and biogas yield. Batchwise digestion of sisal pulp and fish waste was studied both with the wastes separately and with mixtures in various proportions. While the highest methane yields from sisal pulp and fish waste alone were 0.32 and 0.39 m(3) CH4/kg volatile solids (VS), respectively, at total solid (TS) of 5%. co-digestion with 33% of fish waste and 67% of sisal pulp representing 16.6% of TS gave a methane yield of 0.62 m(3) CH4/kg VS added. This is an increase of 59-94% in the methane yield as compared to that obtained from the digestion of pure fractions at 5% TS. (C) 2004 Elsevier Ltd. All rights reserved.

The utilization of agro-industrial residues to cultivate edible mushrooms is of great environmental importance. However, the use of lignocellulose as carbon source depends on the capacity of the mushroom to produce lignocellulolytic enzymes and to secrete them to the extracellular substrate. Thus, the profile of lignocellulolytic enzymes produced during different phases of cultivation of Pleurotus HK-37 on sisal waste fractions supplemented with cow dung manure was determined. Mushroom cultivation was performed in plastic bags using substrates formulated by mixing various proportions of sisal leaf residues and sisal boles and supplementing with cow dung manure on dry weight basis. A total of three hydrolytic (carboxymethyl cellulase, pectinase and xylanase) and two oxidative (laccase and lignin peroxidase) enzymes produced by Pleurotus HK-37 were analyzed. Among these enzymes assayed, laccase was found to be predominant and highly expressed. After 30 days of incubation, its activity was 158.75 ± 7.66 Ug-1wet spent mushroom substrate (SMS) on 30% supplemented sisal leaf decortication residues: sisal boles (25:75) substrate formulation. The highest lignin peroxidase activity observed was 4.01 ± 1.12 Ug-1wet SMS during full mycelia colonization on unsupplemented sisal leaf decortication residues: sisal boles (25:75) substrate formulation. Meanwhile, for the hydrolytic enzymes; the highest carboxymethyl cellulase activity (5.45 Ug-1wet SMS) was observed on unsupplemeted sisal leaf decortication residues: sisal boles (75:25) substrate formulation 50 days after of substrate inoculation, that of xylanase (3.73 ± 0.98 Ug-1wet SMS) was found on 10% supplemented sisal leaf decortication residues: sisal boles (0:100) substrate formulation after 20 days and that of pectinase (8.28 ± 2.14 Ug-1wet SMS) was observed 20 days after substrate inoculation on 30% supplemented sisal leaf decortication residues: sisal boles (100:0) substrate formulation. The present investigation indicates the utilization of solid sisal wastes as support-substrate for production of both edible mushrooms and extracellular enzymes during solid state fermentation; it also provides an alternative approach and value-addition to these agrowaste residues.