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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.

One of the best options for African countries to meet rural energy needs is to grow care-free crassulacean acid metabolism plants on a massive scale in waste lands. This can enable bioenergy production without disrupting food supplies and hence sustainable energy supply for the future. Opuntia ficus indica is an ideal plant for arid regimes but has barely been studied as a potential bioenergy source. This study investigated the effect of aerobic pretreatment on methane yield of O. ficus indica biomass. This effect was investigated in batch bioreactors which were exposed to aerobic conditions by varying time from 3 to 72 h before the start of anaerobic digestion. Reducing sugar content and dissolved oxygen levels after pretreatment period was analyzed. Reducing sugar content in bioreactors increased with increase in pretreatment time from 12.22 ±0.69 to 59.08 ± 5.35 g/L in the untreated and 72 h pretreated batches, respectively. Methane yields after pretreatment were observed to range from 0.286 to 0.702 L/kg volatile solids at 9 and 72 h of pre-treatment, respectively. A 9 h pre-treatment of feedstock prior to anaerobic digestion yielded 123% higher methane yield when compared to that without pre-treatment. The findings that there was an increase in reducing sugar production and methane yield at 9 h of aerobic pre-treatment suggests that there was increased hydrolysis with pretreatment. Hence, short pre-treatment period could be an option to increasing solubilization of cladodes and promoting methane productivity. Therefore, pre-aeration of O. ficus indica, was shown to be an effective method for enhancing both its digestibility and improved methane yield during anaerobic digestion. Key words: Anaerobic digestion, biogas, methane, Opuntia, pretreatment, spineless cacti.

Consumption of mushroom has increased remarkably because of their desirable aroma, taste and high nutritional content. Wild edible mushrooms (WEM) are well known for their nutritious and antioxidant properties. This study was conducted to measure and compare the antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) of six WEM from selected indigenous Tanzanian forests and one domesticated grown form in methanolic extracts. Results show that among the seven mushroom species extracts, the methanolic extract from Auricularia judae showed the most potent radical scavenging activity of 93.33% while Panus conchatus revealed lowest antioxidant activities of 46.53%. The strongest EC50 was observed in Auricularia judae 0.08 mg/ml while weakest was in P. conchatus >0.3 mg/ml. Nevertheless total phenolics in the methanolic extracts were the highest in P. tenuiculus (431.03±3.63 mg GAE/100 g) and lowest in Macrolepiota procera (136.21±0.98 mgGAE/100 g). Lentinus squarrosulus possessed highest content of β-carotene and flavonoids were 48.15±1.04 mg/100 g and 25.62±1.78 mg/100 g, respectively meanwhile the lowest concentration was found in wild L. sajor-caju 5.35±0.68 mg/100 g and 2.49±1.28 mg/100 g, respectively. Comparatively, domesticated mushroom showed higher scavenging ability of 76.61% than its wild counterparts 62.94%. In conclusion, high antioxidant activity in methanolic extract of WEM due to presence of phenolic content can potentially be used as a source of natural antioxidants. Key words: Wild edible mushrooms, antioxidant activity, polyphenols flavonoids.

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.

Ligninolytic enzyme activities of extracts obtained from sugarcane residues-based substrates during solid-state fermentation (SSF) by Pleurotus sapidus P969 at mycelia colonization; primordial formation; harvesting and postharvest stages were investigated. SFF was performed in plastic bags using substrates formulated by mixing various proportions known weights of sugarcane bagasse (SB) and sugarcane tops (ST) on dry weight basis. Laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP) activities in extracts of the substrates were determined using standard methods. The highest laccase activities reached were 43.94 U g-1 wet spent mushroom substrate (SMS) in SB/ST (60:40) mixed substrate on the first pinhead appearance (1st P.A). The highest manganese peroxidase activities observed were 11.90 U g-1 wet SMS in SB/ST (20:80) mixed substrate on the 1st P.A. The highest lignin peroxidase activities observed were 8.71 U g-1 wet SMS in SB/ST (20:80) mixed substrate after full substrate colonization (A.C). Thus, the results indicate enormous potential of P.sapidus for industrial production of ligninolytic enzymes on very low cost substrates through SSF. The study further demonstrates the possibility of production of specific ligninolytic enzymes by oyster mushrooms through tailor making the substrates using sugar cane-based residues.

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.

In Tanzania wild edible mushrooms collected during the rainy season have broad cultural acceptance and constitute a traditionally very important nutritious food. However, their assessment as food, which is based on their chemical analysis, has not been adequately studied and documented. The objective of the study was to determine the proximate nutritive potential of three indigenous edible wild mushrooms namely Coprinus cinereus, (Schaeff) S. Gray s.lat., Pleurotus flabellatus, (Berk and Br.) Sacc. and Volvariella volvaceae (Bull.ex.Fr) Singer, grown on composted solid sisal decortication residues. Standard procedures were used to determine the proximate chemical composition of dried samples of domesticated indigenous edible wild mushrooms. Atomic absorption spectrophotometry was used to determine the mineral element composition. The results were compared using an analysis of variance test. There were significant differences in the proximate nutritive values of the three edible mushrooms (p>0.05). Despite differences in the chemical composition of the three indigenous edible mushroom species, the overall nutritional potential of the three mushroom species was quite good. Furthermore, the overall results indicated that the fruit bodies of the three native mushrooms studied have nutrient qualities similar to other cultivated exotic edible mushrooms, and a higher protein content than many cereals and vegetables. The results on a dry weight basis demonstrated significant amounts of protein, vitamin C and minerals, ranging from 17-28 %, 33-55 mg/100g and 5.2-3232 mg/100g, respectively. Furthermore crude fibre ranged between 6.6-11 % and carbohydrate, at 50-62 %, both of which were found to be relatively high. All three species were low in fat content, with a range of 1 to 3.3 %, and energy value (calculated), 302-313 kcal/100g. These results indicated that the studied mushrooms have good nutritive value for human beings. The fact that the domesticated mushrooms were grown using locally adapted biotechnology increases the likelihood of their incorporation in the diet as a food item contributing protein, vitamin C and mineral nutrients. The high crude fibre and low fat content are also important from a nutritional perspective. The researchers believe that it would be appropriate to popularise the utilization of the three mushrooms as unconventional protein rich food sources to supplement the traditional cereal Tanzanian based diet, aimed at combating the problem of protein malnutrition in Tanzania in particular and in developing counties in general. Key words : Proximate composition, Wild edible mushrooms

The activity of oxidative and hydrolytic enzymes of the edible and medicinal white rot fungi Coprinus cinereus (Schaeff.) Gray mushroom was observed during mycelia growth and fruiting body development in solid substrate fermentation using sisal waste fractions amended with cow dung manure as supplement. Laccase had the highest titre value among the five detected enzymes. Its activity was higher during mycelia growth compared to fruiting phase, with 10% supplemented substrate formulation unmixed sisal leaf decortication residues [abbreviated SL : SB (100 : 0)] displaying the highest activity of 39.45±12.05 Ug−1. Lignin peroxidase (LiP) exhibited a characteristic wave-like pattern with the highest peaks found either during full mycelia colonization or soon after first flush harvest; the highest activity of 1.93±0.62 Ug−1 was observed on unsupplemented SL : SB (100 : 0) substrate formulation during mycelia colonization. For hydrolytic enzymes, the highest carboxymethyl cellulase (CMCase) activity of 2.03±0.70 Ug−1 was observed on 20% supplemented SL : SB (0 : 100) after first flush; that of pectinase (1.90±0.32 Ug−1) was revealed after third flush on 10% supplemented SL : SB (0 : 100) substrate formulation while 10% supplemented SL : SB (25 : 75) exhibited the highest xylanase activity (1.23±0.12 Ug−1) after first flush. These findings show that the activities of both oxidative and hydrolytic enzymes were regulated in line with developmental phase of growth of Coprinus cinereus.

The degradation and biogas production potential of sisal fibre waste could be significantly increased by pre-treatment for reduction of particle size. Batch-wise anaerobic digestion of sisal fibre waste was carried out in 1-l digesters with fibre sizes ranging from 2 to 100 mm, at an ambient temperature of 33 °C. Sediment from a stabilisation pond at a sisal production plant was used as starter seed. Total fibre degradation increased from 31% to 70% for the 2 mm fibres, compared to untreated sisal fibres. Furthermore, the results confirmed that methane yield was inversely proportional to particle size. Methane yield increased by 23% when the fibres were cut to 2 mm size and was 0.22 m3 CH4/kg volatile solids, compared to 0.18 m3 CH4/kg volatile solids for untreated fibres. By anaerobic digestion and biogas production, the 148,000 tonne of waste sisal fibres generated annually in Tanzania could yield 22 million m3 of methane, and an additional 5 million m3 of methane if pre-treatment by size reduction to 2 mm was applied.

Pre-treatment of sisal pulp prior to its anaerobic digestion was investigated using an activated sludge mixed culture under aerobic conditions in batch bioreactors at 37 degrees C. The progression of aerobic pre-treatment of the residue in relation to the activities of some extracellular hydrolytic enzymes in the slurry was monitored. The highest activity of hydrolytic enzymes was obtained at 9 h of pre-treatment. Filter paper cellulase had a maximum activity of 0.90 IU/ml, while carboxymethyl cellulase, amylase and xylanase were produced to a maximum of about 0.40 IU/ml. The methane yield obtained after anaerobic digestion of the pre-treated pulp ranged between 0.12 and 0.24 m3 CH4/kg VS added. The highest and lowest values were obtained for 9 and 72 h of pre-treatment, respectively. Nine hours of pre-treatment of sisal pulp prior to anaerobic digestion demonstrated a 26% higher methane yield when compared to the sisal pulp without pre-treatment. The consortia of microorganisms in activated sludge demonstrated a useful potential in the production of hydrolases acting on major macromolecules of sisal pulp. The fact that a correlation was observed between high enzyme activity and high methane yield at 9 h of aerobic pre-treatment suggests that such a short pre-treatment period could be an alternative option for increasing solubilization of sisal pulp and promoting methane productivity.

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.

Objective: Indigenous forests in Tanzania provide a good environment for saprophytic wild edible mushrooms (SWEM) to grow. In rural areas, mushroom eaters rely on seasonal collection of wild edible mushrooms during the rain seasons, which make them unreliable source of nutrients during dry seasons. The study aims to identify and domesticate SWEM so that it is available throughout the year. Methodology and results: Eight types of SWEM were identified, collected; their germplasm isolated and experimented for domestication their biological efficiency. Three species out of eight were successfully isolated and included Pluteus umbrosus , Lentinus sajor-caju and Panus conchatus . Of the three isolates, only one species L. sajor-caju was successfully domesticated and formed fruit bodies at 18% biological efficiency. Furthermore, results on vegetative growth on mixed substrates of dried banana (70%) and wood shred (30%) administered at different inoculation rates of 1%, 3% and 5% in glass columns revealed different colonization rates with the highest record of 24.94±0.38 mm/day at 3% spawn inoculation with P. conchatus. Conclusion and application of results: The successful domestication of L. sajor-caju shows the potential of SWEM being cultivated and is a stepping-stone towards more domestication of indigenous mushroom species. More studies on optimizing its growth parameter are recommended for growing and introduction to mushroom growing industry. Keywords: Colonization, Domestication, Indigenous forests, Lentinus sajor-caju , SWEM

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).

Solid sisal waste fractions which included composted sisal boles and sisal leaves decortication residues supplemented with cow dung manure at various rates used singly and/or in combination as substrates were investigated for cultivation of oyster mushroom (Pleurotus HK-37). The effect of the test sisal waste substrates and cow dung manure of various supplementation rates were evaluated by mushroom yield, biological efficiency and mushroom size. Pinheads occurred in all substrates within 3 to 5 weeks of transfer of bags to the cropping room. The overall best results of mushroom production were obtained in a substrate combination of 50 % sisal leaves + 50 % sisal boles (based on 450 g wet weight substrate) supplemented by 30 % cow dung manure with the mushroom yield of 184.64 g fresh mushrooms/kg moist substrate weight and percentage biological efficiency (B.E) of about 63 %. Mushroom size of 6.10 was obtained in sisal boles substrate supplemented by 20 % cow dung manure. Least yield of 26.73 g fresh mushrooms/kg moist substrate weight and lowest B.E of 8.95 % were obtained from non-supplemented substrate of sisal leaves alone. The study concluded that, supplementation using cow dung manure may play an important role on increasing the yield and productivity of Pleurotus HK-37 on solid sisal waste fractions under the conditions investigated.

A single stage anaerobic digester employing a sisal fibre waste fixed bed was studied for biogas production from sisal pulp waste. The fibre was colonized by microorganisms involved in biogas production. The sisal pulp waste to be digested was fed from the top and was sprinkled intermittently with recirculating leachate from the material. Organic loading rates of 0.1-10 kg volatile solids (VS) m-3d-1 could be applied and methane yields in the range of 0.13-0.48 m3 CH4 kg-1 VS added were obtained. The average methane content in the biogas produced from sisal pulp waste was 55%, and the biogas production rate was 0.15-0.54 m3m-3d-1. The methane yield obtained and the highest organic loading rate that could be sustained by this simple, fixed-bed digester are indications of an attractive system in terms of performance and reliability. It is concluded that the sisal fibre waste fixed bed is a promising carrier for microbes and can be employed for long-term operation without changing the bed. Tanzania Journal of Science Vol. 31 (2) 2005: pp. 41-52

Three methanogenic biofilm bioreactors were studied to evaluate the performance of three types of carriers. The carrier material were consisted of sisal fibre waste, pumice stone and porous glass beads, and the bioprocess evaluated was the methanogenesis anaerobic digestion of sisal leaf waste leachate. Process performance was investigated by increasing the organic loading rate (OLR) step-wise. The best results were obtained from the bioreactor packed with sisal fibre waste. It had the highest chemical oxygen demand (COD) removal efficiencies in the range of 80-93% at OLRs in the range of 2.4-25 g COD L -1 d -1 . The degradation pattern of volatile fatty acids (VFAs) showed that the degradation of propionate was limiting at higher OLRs. The stable pH and higher partial alkalinity (PA) of the outflow illustrated that packed-bed bioreactors have a good ability to withstand the variations in load and volatile fatty acid concentrations that can occur in a two-stage anaerobic process. In conclusion, sisal fibre waste was shown to be a novel promising biofilm carrier and would work very well in methanogenic biofilm bioreactors treating sisal leaf tissue waste leachate. Furthermore both sisal wastes are available in the neighbourhood of sisal industries, which makes anaerobic digestion scale up at sisal factory level feasible and cost-effective.

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.