Efficient pullulan production by Aureobasidium pullulans using cost-effective substrates.

In this study, cost-effective substrates such as cassava starch, corn steep liquor (CSL) and soybean meal hydrolysate (SMH) were used for pullulan production by Aureobasidium pullulans CCTCC M 2012259. The medium was optimized using response surface methodology (RSM) and artificial neural network (ANN) approaches, and analysis of variance indicated that the ANN model achieved higher prediction accuracy. The optimal medium predicted by ANN was used to produce high molecular weight pullulan in high yield. SMH substrates increased both biomass and pullulan titer, while CSL substrates maintained higher pullulan molecular weight. Results of kinetic parameters, key enzyme activities and intracellular uridine diphosphate glucose contents revealed the physiological mechanism of changes in pullulan titer and molecular weight using different substrates. Economic analysis of batch pullulan production using different substrates was performed, and the cost of nutrimental materials for CSL and SMH substrates was decreased by 46.1% and 49.9%, respectively, compared to the control using glucose and yeast extract as substrates, which could improve the competitiveness of pullulan against other polysaccharides in industrial applications.

Dietary exposure and risk assessment of cyanide via cassava consumption in Chinese population.

The intake of cassava would probably induce adverse health effects since there are toxic cyanide in cassava. However, the risk assessment of cassava consumption has not been reported in China. Therefore, this paper aimed to evaluate the dietary risks of cassava cyanide and proposed a maximum residue limit (MRL) for cyanogenic glycosides (CNGs) in cassava. The retention rate of CNGs and CN- were 61% and 11% after boiling, respectively. The acute dietary exposure of CN- and CNGs were 0.6-fold and 1.7-fold of acute risk reference dose, respectively. There was no chronic health risk across all populations concerning cassava consumption. The MRL of CNGs was proposed as 200 mg/kg in cassava. Risk assessment of cyanide for foods rich in CNGs was suggested to be based on CNGs quantification rather than that of CN-.

Effects of dietary inclusion of Zymomonas mobilis degraded cassava sifting on growth performance, apparent nutrient digestibility, ileal digesta viscosity, and economy of feed conversion of broiler chickens.

A study was carried out to evaluate the effect of dietary inclusion of Zymomonas mobilis degraded cassava sifting (ZDCS) on growth response, apparent nutrient digestibility, and ileal digesta viscosity of broiler chickens. Five diets containing undegraded and degraded cassava sifting were formulated to replace wheat offal at 0, 50, and 100% levels. Two hundred and forty (240) one-day-old Marshall broiler chickens were randomly allotted to the five dietary treatments in a completely randomized design (CRD); significant means were separated using Duncan's multiple range test at p < 0.05. The biodegradation of cassava sifting with Zymomonas mobilis significantly increased crude protein content by 44.59% while crude fiber and neutral detergent fiber significantly decreased by 23.08% and 6.38%, respectively. The results showed that birds fed 50% ZDCS had the best (p > 0.05) feed conversion ratio (FCR) at the starter phase. The replacement of wheat offal with 100% ZDCS improved (p < 0.05) the crude fiber digestibility at both starter and finisher phases. Also, the birds fed 100% ZDCS had the lowest (p < 0.05) value of ileal digesta viscosity. The birds fed 50% ZDCS had the highest (p < 0.05) values of gross revenue, gross profit, rate of return on investment, and economic efficiency while the least values for gross profit, rate of return on investment, and economic efficiency were obtained in 100% ZDCS. The study concluded that replacement of wheat offal with 50% ZDCS in the ration of broiler chickens improved FCR, crude fiber digestibility (CFD), and rate of return on investment and economic efficiency.

Adding value to lignocellulosic wastes via their use for endoxylanase production by Aspergillus fungi.

Agroforestry industries in the world generate lignocellulosic wastes that can be a huge problem of pollution, or the wastes can be used for different biotechonological applications such as substrates for microorganism growth and enzyme production. Fungi such as Aspergillus niger can grow in almost every substrate and produce hydrolytic enzymes such as endoxylanases, giving added value to agroforestry wastes generated by industries in the northeast of Argentina. In this context, the aim of this work was to use agroforestry wastes as substrates for the production of endoxylanases by Aspergillus niger and to optimize nitrogen sources and physical variables for the highest endoxylanase activity. A. niger LBM 055 and A. niger LBM 134 produced high endoxylanase levels when they were grown with sugarcane and cassava bagasses as carbon sources. A. niger LBM 134 reached the highest endoxylanase activity when nitrogen sources and physical variables were optimized. The fungus exhibited up to 110 U mL-1 of endoxylanase activity when it was grown with sugarcane bagasse and more than 160 U mL-1 with cassava bagasse. Therefore, endoxylanase production was optimized using agricultural bagasses and cost 20 times less than enzyme production using synthetic xylan.

Will farmers intend to cultivate Provitamin A genetically modified (GM) cassava in Nigeria? Evidence from a k-means segmentation analysis of beliefs and attitudes.

Analysis of market segments within a population remains critical to agricultural systems and policy processes for targeting new innovations. Patterns in attitudes and intentions toward cultivating Provitamin A GM cassava are examined through the use of a combination of behavioural theory and k-means cluster analysis method, investigating the interrelationship among various behavioural antecedents. Using a state-level sample of smallholder cassava farmers in Nigeria, this paper identifies three distinct classes of attitude and intention denoted as low opposition, medium opposition and high opposition farmers. It was estimated that only 25% of the surveyed population of farmers was highly opposed to cultivating Provitamin A GM cassava.

Economically enhanced succinic acid fermentation from cassava bagasse hydrolysate using Corynebacterium glutamicum immobilized in porous polyurethane filler.

An immobilized fermentation system, using cassava bagasse hydrolysate (CBH) and mixed alkalis, was developed to achieve economical succinic acid production by Corynebacterium glutamicum. The C. glutamicum strains were immobilized in porous polyurethane filler (PPF). CBH was used efficiently as a carbon source instead of more expensive glucose. Moreover, as a novel method for regulating pH, the easily decomposing NaHCO3 was replaced by mixed alkalis (NaOH and Mg(OH)2) for succinic acid production by C. glutamicum. Using CBH and mixed alkalis in the immobilized batch fermentation system, succinic acid productivity of 0.42gL(-1)h(-1) was obtained from 35gL(-1) glucose of CBH, which is similar to that obtained with conventional free-cell fermentation with glucose and NaHCO3. In repeated batch fermentation, an average of 22.5gL(-1) succinic acid could be obtained from each batch, which demonstrated the enhanced stability of the immobilized C. glutamicum cells.

Comparative assessment of the methanogenic steps of single and two-stage processes without or with a previous hydrolysis of cassava distillage.

In this study, cassava distillage with a high solid content was digested in an anaerobic sequencing batch reactor (ASBR) without or with a previous hydrolytic step by a cellulolytic microbial consortium (i.e., single or two-stage process). The methanogenic steps of these processes were compared and evaluated through observation of the methanogenic stability and methane yield under different organic loading rates (OLRs). It was found the methanogenic reactor can be stably performed with the OLRs lower than 20 g COD L(-1) d(-1) in the two-stage process, where a specific methane yield (0.147 L CH4 g(-1) CODremoved) could be achieved, which was 17.6% higher than that of the single-stage process (0.125 L CH4 g(-1) CODremoved). The above results indicated that the degradation of cassava distillage in a two-stage process with a previous hydrolytic step can assure the methanogenic process proceeds with greater stability and generates higher methane yield.

[Evaluation of the cellulase cost during the cassava cellulose ethanol fermentation process].

Cellulose takes nearly 10% (W/W) dry weight of cassava tubers. In this study, the cellulase cost of different ethanol fermentation from cassava cellulose was evaluated. The processes include the direct saccharification and fermentation of original cassava cellulose residues, the direct saccharification and fermentation of pretreated cassava cellulose residues, and the simultaneous co-saccharification and fermentation of cassava starch and cassava cellulose. The results show that the cassava cellulose utilization in the first two processes were low with the enzyme cost of 13 602 and 11 659 RMB Yuan per tone of ethanol, respectively. In the third process, the final ethanol concentration increased from 101.5 g/L to 107.0 g/L when cassava cellulose and cassava starch were saccharified simultaneously. Comparing to the first two processes, the third one demonstrated the lowest enzyme cost at 3 589 RMB Yuan per ton of ethanol, which was less than the ethanol price and no additional equipment and operation cost input were added. The conclusion provided a practical way of cassava cellulose utilization in cassava ethanol industry.

Repeated-batch fermentation using flocculent hybrid, Saccharomyces cerevisiae CHFY0321 for efficient production of bioethanol.

In this study, the repeated-batch fermentation of liquefied cassava medium using the flocculent hybrid Saccharomyces cerevisiae CHFY0321 was investigated for semicontinuous, high-throughput production of bioethanol. Cassava medium was selected due to the industrial requirement for a cheap starchy substrate. Fermentations were performed by simultaneous saccharification and fermentation (SSF) with a set of ten batches successfully completing a series within the repeated fermentation process. In addition, pH of the culture medium was not controlled to simplify ethanol production for future use in industry. Optimal recycling volume was found to be 5%. Volumetric productivity, final ethanol concentration, and ethanol yield were measured at 3.34 g l(-1) h(-1), 84.5 g l(-1), and 90.7%, respectively. Cell recycling (24.5 g DCW l(-1)) resulted in 1.8-fold decrease in fermentation time (24 h) and 1.8-fold increase in volumetric productivity compared with the ordinary batch fermentation. Therefore, repeated-batch SSF using flocculent CHFY0321 demonstrates the possibility of cost-effective bioethanol production by eliminating additional saccharification and inoculation steps.

Agricultural biotechnology and its contribution to the global knowledge economy.

The theory of neoclassical welfare economics largely shaped international and national agricultural policies during the Cold War period. It treated technology as an exogenous factor that could boost agricultural productivity but not necessarily sustainable agriculture. New growth theory, the economic theory of the new knowledge economy, treats technological change as endogenous and argues that intangible assets such as human capital and knowledge are the drivers of sustainable economic development. In this context, the combined use of agricultural biotechnology and information technology has a great potential, not just to boost economic growth but also to empower people in developing countries and improve the sustainable management of natural resources. This article outlines the major ideas behind new growth theory and explains why agricultural economists and agricultural policy-makers still tend to stick to old welfare economics. Finally, the article uses the case of the Cassava Biotechnology Network (CBN) to illustrate an example of how new growth theory can be applied in the fight against poverty. CBN is a successful interdisciplinary crop research network that makes use of the new knowledge economy to produce new goods that empower the poor and improve the productivity and nutritional quality of cassava. It shows that the potential benefits of agricultural biotechnology go far beyond the already known productivity increases and pesticide use reductions of existing GM crops.

Agricultural and food policies. Some concerns regarding their nutritional relevance.

In recent times, nutrition analysts have been emphasizing the fact that the most critical nutritional unfulfilled need in underdeveloped countries is energy or quantity of food. This has prompted some leading food economist and agricultural policy makers to promote the extensive cultivation of high field inexpensive staples, including starchy roots and tubers. A typical example is cassava in many African countries and Indonesia. These foods not only have very little and poor quality protein, but also lack other essential nutrients. Interestingly, underdeveloped populations seem to select the nutritionally poorest staples under condition of extreme economic constraints, for example cassava or sorghum. But as their economic level improves they switch to nutritionally better staples, like wheat or rice. The people seem to be able to <> the need for quality rather than simply quantity as soon as an improved economic status allows them more choices. Some examples are given to support this contention. The present analysis emphasizes that the goals and objectives of nutrition scientists must be integrated with those of food and agricultural economists for the design of agricultural policies with increased relevance to human nutrition in a comprehensive way. Rather than proposing the cultivation of one inexpensive staple, these policies should consider a variety of complementary foods which would allow the people to chose diets providing sufficient quantities and balance of all essential nutrients in addition to energy.