Gossypol Levels Research Articles

Effect of feeding of calcium hydroxide-treated or vitamin E-supplemented cottonseed meal on plasma gossypol levels, blood parameters, and performance of Bikaneri lambs

To study the effect of feeding calcium hydroxide-treated or vitamin E-supplemented cottonseed meal (CSM) incorporated diets on plasma gossypol, blood parameters and animal performance, 24 male Bikaneri lambs of 6-7 months of age and of uniform body weight were divided into four groups of six animals each in a completely randomized design and respectively fed isonitrogenous and isocaloric concentrate mixtures containing 20% soybean meal (CON) or 40% raw CSM (RCSM), 40% raw CSM supplemented with 500 IU of vitamin E per head per day (ERCSM), and 40%, 1.5% calcium hydroxide-treated CSM (CaCSM) along with ad libitum wheat straw throughout 510 days of experimental feeding. The lambs on all the diets grew linearly throughout the experimental period. The total weight gain, in turn the average daily gain (ADG), was not affected by dietary variations. The daily intake of dry matter, crude protein (CP), digestible crude protein (DCP) and total digestible nutrients (TDN) were found comparable among lambs of all the groups. Though total gossypol intake was similar in RCSM, ECSM and CaCSM groups, however, free gossypol intake was significantly higher (P < 0.01) in RCSM, ECSM groups as compared to CaCSM group. Serum iron and blood hemoglobin levels were significantly (P < 0.05) lower in RCSM group as compared to CaCSM and CON groups, and ALT activity was significantly (P < 0.05) higher on RCSM group as compared to other groups. Plasma gossypol and osmotic fragility of erythrocytes were significantly (P < 0.05) increased in RCSM group as compared to CaCSM and ERCSM groups. However, there was no significant difference in the concentration of other blood/serum biochemical constituents among the lambs on different groups. Based on the results, it may be concluded that feeding of 40% CSM in the concentrate mixture of the diet in Bikaneri lambs did not have any major adverse effect in blood parameters and animal performance. Either calcium hydroxide treatment or vitamin E supplementation did not produce any major additional benefits.

RNAi‐mediated Ultra‐low gossypol cottonseed trait: performance of transgenic lines under field conditions

Cottonseed remains a low-value by-product of lint production mainly due to the presence of toxic gossypol that makes it unfit for monogastrics. Ultra-low gossypol cottonseed (ULGCS) lines were developed using RNAi knockdown of δ-cadinene synthase gene(s) in Gossypium hirsutum. The purpose of the current study was to assess the stability and specificity of the ULGCS trait and evaluate the agronomic performance of the transgenic lines. Trials conducted over a period of 3years show that the ULGCS trait was stable under field conditions and the foliage/floral organs of transgenic lines contained wild-type levels of gossypol and related terpenoids. Although it was a relatively small-scale study, we did not observe any negative effects on either the yield or quality of the fibre and seed in the transgenic lines compared with the nontransgenic parental plants. Compositional analysis was performed on the seeds obtained from plants grown in the field during 2009. As expected, the major difference between the ULGCS and wild-type cottonseeds was in terms of their gossypol levels. With the exception of oil content, the composition of ULGCS was similar to that of nontransgenic cottonseeds. Interestingly, the ULGCS had significantly higher (4%-8%) oil content compared with the seeds from the nontransgenic parent. Field trial results confirmed the stability and specificity of the ULGCS trait suggesting that this RNAi-based product has the potential to be commercially viable. Thus, it may be possible to enhance and expand the nutritional utility of the annual cottonseed output to fulfil the ever-increasing needs of humanity.

Effects of different sources and levels of dietary gossypol on gossypol residues in plasma and milk of lactating cows

Free gossypol residues in tissues or milk from feeding whole cottonseed and cottonseed meal were measured for their effect on health of dairy cows and humans. Forty lactating cows were randomly assigned to 5 treatments in a 60-d experiment to investigate the effects of sources and dietary level of gossypol on plasma and milk gossypol concentrations in lactating cows. Five experimental diets had identical net energy for lactation and crude protein content on a dry matter (DM) basis. Soybean meal was the main protein ingredient used in the control diet. Cottonseed meal (CSM) or whole cottonseed (WCS) substituted for part of the soybean meal in the other 4 diets. Gossypol levels in the 5 diets were 0 (control), 91.15mg/kg of DM in CSM1, 117.31mg/kg of DM in CSM2, 385.43mg/kg of DM in WCS1, and 611.13mg/kg in WCS2. Yields of 3.5% fat-corrected milk were significantly higher for cows in the WCS2 group; cows in the CSM1 and WCS1 groups showed no differences but both were numerically higher than the control and CSM2 groups. Milk protein concentration was lower for cows consuming WCS1 compared with the control group. Lactose concentration was lower for cows in the CSM2 group compared with the WCS2 group, but no differences were observed among other diets. Aspartate aminotransferase in serum was significantly higher for the WCS2 group compared with the control and WCS1 groups, but no difference was observed with the CSM1 and CSM2 groups. Concentrations of gossypol in plasma and milk of cows in the WCS1 and WCS2 groups were both higher than those of the other groups. No adverse effects were observed on cows fed diets containing 12.0% CSM, and no gossypol was found in plasma and milk. When WCS comprised 15% of the diet DM, yields of 3.5% fat-corrected milk were increased in cows and gossypol was detected in plasma and milk but not at harmful levels.

Alleviation of reproductive toxicity of gossypol using selenium supplementation in rams1

The objective of this study was to evaluate the reproductive toxicity of gossypol and the possible counteracting effect of selenium supplementation in rams. Twenty-five mature crossbred (Barki × Rahamni) rams were randomly divided into 5 equal groups. The first group served as a control (no gossypol in diet). The second and third groups received diets containing free gossypol of 9 and 14 mg·kg(-1) BW·d(-1)(low level and high level of gossypol), respectively. The fourth and fifth groups received the same diets given to the second and third groups, respectively, with an oral administration of 1 mg selenium (as sodium selenite) daily for each animal. Results showed reductions in ejaculate volume (P = 0.028), percentage of dead sperm (P = 0.003), total functional sperm fraction (P < 0.001), and blood serum concentration of testosterone (P < 0.001) in the presence of both levels of gossypol inclusion. Furthermore, high level of gossypol reduced forward motility (P < 0.001) and semen initial fructose concentration (P = 0.002) and increased abnormal-head sperm (P = 0.003) and blood serum concentration of triiodothyronine (P = 0.006). Regardless of selenium supplementation, increasing level of free gossypol in diet resulted in a significant decrease in the percentage of forward motility (P = 0.037) and significant increases in the mean values of sperm concentration (P < 0.001), total sperm output (P = 0.002), percentage of total abnormal sperm (P = 0.058), and abnormal-head sperm (P = 0.016). On the other hand, regardless of levels of gossypol inclusion, selenium supplementation resulted in significant increases in libido (P < 0.001), mean values of ejaculate volume (P < 0.001), percentage of forward motility (P = 0.019), total sperm output (P < 0.001), total functional sperm fraction (P < 0.001), semen initial fructose concentration (P = 0.031), and blood serum concentrations of both testosterone and triiodothyronine (P < 0.001). In conclusion, free gossypol in diet induced adverse effects on semen quality in rams, but selenium supplementation successfully counteracts most of the hazardous effects of gossypol on semen characteristics.

Hemigossypol, a Constituent in Developing Glanded Cottonseed (Gossypium hirsutum)

Gossypol is a dimeric sesquiterpenoid first identified in cottonseed, but found in various tissues in the cotton plant including the seed. From its first discovery, it was assumed that hemigossypol was the biosynthetic precursor of gossypol. Previous studies established that peroxidase (either from horseradish or from cottonseed) converts hemigossypol to gossypol. However, hemigossypol has never been identified in healthy cottonseed. In a temporal study using HPLC and LC-MS, hemigossypol was identified in the developing cotton embryo. It was shown to concomitantly accumulate until 40 days postanthesis (dpa) with gossypol and with transcripts of δ-cadinene synthase and 8-hydroxy-δ-cadinene synthase, genes involved in the biosynthesis of hemigossypol and gossypol. After 40 dpa, hemigossypol and its biosynthetic gene transcript levels declined, whereas the gossypol level remained almost unchanged until the bolls were open. These results provide further evidence to support the previous findings that establish hemigossypol as the biosynthetic precursor of gossypol.

Varying Planting Dates or Irrigation Regimes Alters Cottonseed Composition

Despite continued utilization of cottonseed (Gossypium hirsutum L.), little information exists regarding the effect of production factors on cottonseed composition. The objective of this study was to determine how irrigation regime and planting date affect cottonseed composition. Six cotton cultivars were planted early (late April) and at a normal time (late May) in a field near Stoneville, MS, from 2005 to 2008. Half of the plots were irrigated and half were cultivated dry. Seed from the 2006 through 2008 seasons were analyzed for protein, crude oil, gossypol, soluble carbohydrates, and the oil's fatty acid composition. Irrigation increased oil and total soluble carbohydrate levels by 7 and 4%, respectively, and reduced protein levels by 10%. Irrigation also increased the level of total gossypol by 21%, modestly decreased the percentage of the gossypol (+) isomer, and slightly decreased the level of saturated fatty acids in the oil. Early planting decreased gossypol in the seed kernel by 8% under dryland conditions but not under irrigated conditions. The early planting effect on the fatty acid distribution was similar to the effect observed under dryland conditions, but the differences were more modest. Early planting and irrigation offer potential for improved fiber and seed yield but with altered seed composition. Given the proper economic incentives, producers could alter some production strategies to produce seed with more valuable composition traits.

Detection of a Toxic Phenolic Compound in Cottonseed Extract and its Products

2 Abstract: Cottonseed is a good source of high quality meal and edible oil. However, it contains a toxi c phenolic compound called gossypol. Gossypol is an anti-nutritious factor that limits the use of cottonseed and its products due to its toxicity associated to its reactions with amino acids and minerals. This is the first study on gossypol ever conducted in Pakistan. The purpose of this study was to estimate the level of gossypol in oil and ghee (Hydrogenated oil) samples from local markets so that awareness can be created regarding maintenance of minimum gossypol level in edible oils. During this study gossypol was extracted from cottonseeds and cotton seed cake using different organic solvents. The compound was detected in extracts by applying Chromatographic technique as well as chemical tests with SbCl3, Pb(CH3COO)2 and SnCl3. Spectrophotometric techniques were also employed for quantitative analysis by measurin g absorbance of samples at wavelength of 290 nm. It was found that overall the contents of gossypol were higher in cottonseed oils as compared to Ghee (hydrogenated oil).

Responses of three successive generations of beet armyworm, Spodoptera exigua, fed exclusively on different levels of gossypol in cotton leaves.

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is an important pest of numerous crops, and it causes economic damage in China. Use of secondary metabolic compounds in plants is an important method used to control this insect as a part of integrated pest management. In this study the growth, development, and food utilization of three successive generations of S. exigua fed on three cotton gossypol cultivars were examined. Significantly longer larval life-spans were observed in S. exigua fed on high gossypol cultivar M9101 compared with those fed on two low gossypol cultivars, ZMS13 and HZ401. The pupal weight of the first generation was significantly lower than that of the latter two generations fed on ZMS13 group. Significantly lower fecundity was observed in the second and third generations of S. exigua fed on M9101 compared with S. exigua fed on ZMS13 and HZ401. The efficiency of conversion was significantly higher in the first and third generations fed on HZ401 compared with those fed on ZMS13 and M9101. A significantly lower relative growth rate was observed in the three successive generations fed on M9101 compared with those fed on ZMS13 and HZ401. Cotton cultivars significantly affected the growth, development, and food utilization indices of S. exigua, except for frass and approximate digestibility. Development of S. exigua was significantly affected by relative consumption rate and efficiency of conversion of ingested food, but not by relative growth rate or approximate digestibility, suggesting that diet-utilization efficiency was different based on food quality and generation. Measuring the development and food utilization of S. exigua at the individual and population levels over more than one generation provided more meaningful predictions of long-term population dynamics.

Plasma gossypol dynamics in white-tailed deer: Implications for whole cottonseed as a supplemental feed

Whole cottonseed (WCS) is a potential supplemental feed for white-tailed deer ( Odocoileus virginianus) in rangeland conditions because of its high digestible energy and protein content, moderate fiber content, and resistance to degradation in moist conditions. WCS also contains the polyphenolic secondary metabolite gossypol, which reduces palatability to non-target monogastric species but may be of concern for deer nutrition. Plasma gossypol stabilization when fed a constant dry matter intake, plasma gossypol depletion after WCS was removed from the diet, and the relationship between WCS consumption and plasma gossypol concentration was studied in 10 mature male ( N = 5) and female ( N = 5) captive white-tailed deer. Consumption of WCS by 73 free-ranging white-tailed deer (59 males, 14 females) was estimated using results of the captive study. Plasma gossypol concentrations declined exponentially and averaged 0.74 μg/mL 35 days after WCS was removed from the diet. Plasma gossypol concentration was linearly related to WCS consumption ( P < 0.001), with females having 0.35 μg/mL greater ( P = 0.04) plasma gossypol than males for a given rate of dry matter consumption. All female and 93% of male white-tailed deer captured in WCS supplemented pastures had detectable plasma gossypol. Female averaged 1.88 μg/mL of plasma gossypol and males averaged 4.84 μg/mL of plasma gossypol. Based on the captive deer data, these plasma values suggest an average WCS consumption of ∼2.6 g/kg BW/day for female free-ranging deer and ∼5.6 g/kg BW/day for male free-ranging deer. Inferentially, a large proportion of free-ranging white-tailed deer in rangeland conditions will consume WCS, with females consuming 125 g WCS/day and males consuming 428 g WCS/day. That plasma gossypol levels decrease rapidly after cottonseed is removed from the diet suggests that the long withdrawal periods often used prior to breeding season may not be needed. However, although 93% of gossypol was eliminated from the animals after a five-week withdrawal period, a small amount of gossypol can still be detected. While our preliminary data on these animals suggests that these levels are not detriment to animal health or reproduction, ranch managers may want to take a conservative approach to the feeding of WCS until these questions are answered.

Effects of pigment glands and gossypol on growth, development and insecticide-resistance of cotton bollworm ( Heliothis armigera (Hübner))

Cotton bollworm ( Heliothis armigera) is a major pest of cotton and other crops. It is important to understand the mechanisms of insecticide tolerance of cotton bollworm on cotton cultivars with host plant resistance to this insect pest. The objectives of this study were to investigate the effects of cotton pigment glands and their gossypol on the growth, development and insecticide tolerance of cotton bollworm. Three pairs of cotton isogenic lines with glanded versus glandless leaves, as well as artificial diets with 5 levels of gossypol, were used to raise cotton bollworm larvae for five generations. The growth, development and insecticide tolerance of larvae were studied. The results indicated that the cotton pigment glands and higher levels of gossypol resulted in a significant decrease in larval weights and moth eclosion rates and delayed the development of larvae and pupae. Larvae that fed on glanded cotton leaves were significantly more tolerant to two insecticides, cyhalothin and monocrotophos, than those fed on glandless cotton leaves. LD 50 values were only increased where they were in amount per unit body weight, and not where were calculated in amount per individual. Also the insecticide tolerance of cotton bollworm larvae increased as the gossypol content was raised from 0 to 0.225% in artificial diets. Meanwhile, the activities of two detoxifying enzymes, carboxylesterase and glutathione s-transferase, were significantly higher in the larvae fed on glanded cotton leaves than those fed on glandless cotton leaves. The activities of two enzymes also increased greatly with the increase of gossypol content from 0 to 0.225% in artificial diets. Across 5 generations of feeding and investigation, the significant inhibition effect on larval growth and larval tolerance to two pesticides were found to be only associated with the feeding by current generation, but were not related to previous diets. The activities of two detoxifying enzymes in larvae were also not enhanced significantly when they were fed continuously on glanded cotton leaves or artificial diet with high gossypol. These results indicated that pigment glands and higher levels of gossypol not only inhibited the growth of cotton bollworm larvae but also enhanced their insecticide tolerance. However, the inhibition effect and enhanced insecticide tolerance were inducible but could not be accumulated or inherited. These results will help us better understand the interaction and co-evolution of insecticide tolerance in larvae of cotton bollworm and host chemical components, and also has provided useful information on cotton bollworm management in cotton production, especially in glandless cotton.

COMPARISON OF SOYBEAN MEAL AND COTTONSEED MEAL VARIETY PAK (CSMP) ON GROWTH AND FEED USING IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

Apparent digestibility coefficients (ADC) were calculated by using chromic oxide in the diet as an indigestible marker to evaluate the Iranian Cottonseed meal (CSMP). Then, the nutritional value of cottonseed meal ( CSM) as soybean meal (SBM) substitute in quality low cost rainbow trout ( Oncorhynchus mykiss ) ration was investigated. In this study, six formulated feeds consisting different levels of CSMP (0, 20, 40, 60, 80, 100%) substitution of SBM were fed to a total of 540 rainbow trout with initial mean body weight of 50 ± 5 g. Fish were randomly stocked into eighteen 100L fiberglass tanks with 30 fish per tank and 3 tanks per diet and fed to apparent satiation 3 times a day and 7 days per week for 60 days. The ADC of CSMP and SBM were measured as of dry matter, 62.7 and 69.2%; crude protein, 82.4 and 87.3%; fat, 66.6 and 78.5%, respectively. After an 8 week feeding trial, the average weight gain of fish fed with diets 1 to 6 was: 100.6, 102, 102.9, 103.3, 103.9, and 103.4g, respectively. Average feed conversion ratio (FCR) of fish fed diets 1 to 6 was measured as of 1.28, 1.31, 1.31, 1.27, 1.29, and 1.25, respectively. For all six treatments, the survival percentage was more than 99%. ADC value for most nutrients of CSMP was different from those of SBM. Weight gain, specific growth ratio (SGR), daily weight gain (DWG) and survival rate were not significantly different (P>0.05) for fish fed with CSMP diets compared to the control diet but the differences of FCR were significant among different diets (P<0.05). In the feasibility study, complete replacement of SBM by CSMP revealed to be economic and based on the gossypol analysis, total gossypol levels was not observed for toxicity on liver of fish fed by CSMP, indicating the possibility of total replacement of SBM by CSMP in rainbow trout fed formulations.

Effect of elicitors on the production of gossypol and methylated gossypol in cotton hairy roots

The effect of two chemical elicitors, salicylic acid and methyl jasmonate, on the production of gossypol, 6-methoxygossypol, and 6,6′-dimethoxygossypol in Gossypium barbadense hairy roots was examined. Methyl jasmonate, but not salicylic acid, was found to increase the production of gossypol and its methylated forms, but with a concomitant reduction in culture growth. The optimal methyl jasmonate dose was between 100 and 300 μM for hairy roots harvested 7 days after elicitation. After 20 d of induction with 100 μM methyl jasmonate, an eightfold increase in the level of gossypol was observed in elicited cultures compared with control cultures, double the highest gossypol levels previously reported for any cotton tissue. A two to threefold increase in the level of 6-methoxygossypol and a slight increase in the levels of 6,6′-dimethoxygossypol were also observed. Although methyl jasmonate stimulated the production of both optical forms of gossypol, the distribution of the enantiomers was different between elicited and control cultures.

Optimisation of fermentation medium for the detoxification of free gossypol in cottonseed powder byGeotrichum candidum G07 in solid-state fermentation with response surface methodology

Plackett-Burman design and response surface methodology were adopted to optimise the fermentation medium forGeotrichum candidum G07 to detoxify free gossypol in cottonseed powder by the solid-state fermentation. Results showed that the optimum medium was composed (%, w/w) of 1.63 (NH4)2SO4, 0.10 KH2PO4, 0.05 MnSO4, 0.1 MgSO4, 0.2 CaCl2 and 62.19 initial moisture content. The residual free gossypol level decreased from 144.0 μg g−1 to 30.42 μg g−1 after incubating at 30 °C for 48 h in the optimised conditions and the detoxification efficiency reached 78.9%, which indicated thatG. candidum G07 was a useful strain to detoxify free gossypol in cottonseed powder and the statistical methods adopted in this paper were effective and powerful. This study can contribute towards decreasing the residual level of free gossypol in cottonseed powder, and can benefit the full use the agricultural residue.

Lowering seed gossypol content in glanded cotton (Gossypium hirsutum L.) lines

AbstractCottonseed is a rich source of high quality protein, but its value as an animal feed is limited by gossypol, a toxic polyphenolic compound contained in glands located throughout the plant. This compound helps protect the plant from pests. Totally glandless varieties have been developed, but not adopted as these plants are left vulnerable to pests. This study describes a breeding strategy to decrease the levels of gossypol in the seed while maintaining a high enough concentration of toxin in vegetative plant parts to offer protection from pests. Preliminary studies indicated that crosses between varieties with different gland densities and distributions produced a range of glanding patterns. By selecting within the resulting progeny, we have identified F7 generation progeny that have &lt;0.30% total gossypol in the seed, while still possessing glands at critical locations on the vegetative plant parts. These new lines will be a valuable source of germplasm for developing low seed gossypol varieties. Seed from these varieties would provide a new source of inexpensive protein for animal feeding rations.

Induction of hairy root cultures from Gossypium hirsutum and Gossypium barbadense to produce gossypol and related compounds

Hairy root cultures were induced by inoculating cotyledonary leaves and hypocotyl segments from two cotton species, Gossypium hirsutum and Gossypium barbadense, with Rhizobium rhizogenes 15834. For both species, more hairy roots formed on inoculation sites on cotyledonary leaves than on hypocotyls. The addition of sucrose to basal Murashige–Skoog media increased the frequency of hairy root formation, whereas the addition of naphthalene acetic acid (0.54 μM) did not. After transfer to a liquid culture, hairy root growth was very rapid. After 3 wk in liquid culture, both cotton species produced gossypol, a di-sesquiterpene secondary metabolite with known anticancer activity, and two related methylated derivatives. Most (60–95%) gossypol produced by cultures was retained within the hairy root tissues, but some was found in the media. The average gossypol level observed among 96 different cultures was 15 mg/g of dry culture mass; however, some cultures produced >40 mg/g of dry culture mass. Variation in gossypol levels was greater for cultures arising from different transformation events than for multiple subclones of a single transformant. The high level of gossypol production attained by most of these cultures suggests that they will be valuable for studying the biochemical and molecular aspects of gossypol biosynthesis, capable of producing large amounts of gossypol and related compounds, and useful for generating modified forms of gossypol (e.g., radio-labeled gossypol) for understanding bioactivity mechanisms.

Preparation of an edible cottonseed protein concentrate and evaluation of its functional properties

Cottonseed could be used as a source of dietary protein for human food production. The cottonseed component, gossypol, is toxic, however, which has limited the potential of cottonseed in human food production. Free gossypol was removed from glanded cottonseed using a two-stage solvent extraction method utilizing aqueous and anhydrous acetone. A cottonseed protein concentrate with a low level of free gossypol and a protein content of 72.2% was obtained. The cottonseed protein concentrate had good organoleptic characteristics, and had functional properties allowing its use as a food additive.

Engineering cottonseed for use in human nutrition by tissue-specific reduction of toxic gossypol.

Global cottonseed production can potentially provide the protein requirements for half a billion people per year; however, it is woefully underutilized because of the presence of toxic gossypol within seed glands. Therefore, elimination of gossypol from cottonseed has been a long-standing goal of geneticists. Attempts were made to meet this objective by developing so-called "glandless cotton" in the 1950s by conventional breeding techniques; however, the glandless varieties were commercially unviable because of the increased susceptibility of the plant to insect pests due to the systemic absence of glands that contain gossypol and other protective terpenoids. Thus, the promise of cottonseed in contributing to the food requirements of the burgeoning world population remained unfulfilled. We have successfully used RNAi to disrupt gossypol biosynthesis in cottonseed tissue by interfering with the expression of the delta-cadinene synthase gene during seed development. We demonstrate that it is possible to significantly reduce cottonseed-gossypol levels in a stable and heritable manner. Results from enzyme activity and molecular analyses on developing transgenic embryos were consistent with the observed phenotype in the mature seeds. Most relevant, the levels of gossypol and related terpenoids in the foliage and floral parts were not diminished, and thus their potential function in plant defense against insects and diseases remained untouched. These results illustrate that a targeted genetic modification, applied to an underutilized agricultural byproduct, provides a mechanism to open up a new source of nutrition for hundreds of millions of people.

Effect of selected fungi on the reduction of gossypol levels and nutritional value during solid substrate fermentation of cottonseed meal

The objective of this work was to investigate the effect of six individual strains of fungi on the reduction of gossypol levels and nutritional value during solid substrate fermentation of cottonseed meal (CSM). Six groups of disinfected CSM substrate were incubated for 48 h after inoculation with either of the fungi C. capsuligena ZD-1, C. tropicalis ZD-3, S. cerevisae ZD-5, A. terricola ZD-6, A. oryzae ZD-7, or A. niger ZD-8. One not inoculated group (substrate) was used as a control. Levels of initial and final free gossypol (FG), crude protein (CP), amino acids (AA) and in vitro digestibility were assayed. The experiment was done in triplicate. The experimental results indicated that microbial fermentation could greatly decrease (P<0.05) FG levels in CSM. The detoxification efficiency differed between the species of microorganisms applied. From the perspective of reducing CSM potential toxicity, C. tropicalis ZD-3 was most successful followed by S. cerevisae ZD-5 and A. niger ZD8. They could reduce FG levels of CSM to 29.8, 63.07 and 81.50 mg/kg based on DM (dry matter), respectively, and their detoxification rate were 94.57%, 88.51% and 85.16%, respectively. If crude protein, amino acids content and their in vitro digestibility were also taken into account, A. niger ZD-8 may be the best choice. The CP content of CSM substrate fermented by C. tropicalis ZD-3 and A. niger ZD-8 were improved by 10.76% and 22.24%; the TAA (total amino acids) contents were increased by 7.06% and 11.46%, and the EAA (essential amino acids) were raised by 7.77% and 12.64%, respectively. Especially, the levels of methionine, lysine and threonine were improved greatly (P<0.05). The in vitro CP digestibility of CSM fermented by C. tropicalis ZD-3 and A. niger ZD-8 was improved by 13.42% and 18.22%, the TAA were increased by 17.75% and 22.88%, and the EAA by 16.61% and 21.01%, respectively. In addition, the in vitro digestibility of methionine, lysine and threonine was also improved greatly (P<0.05).

A Study on the Reduction of Gossypol Levels by Mixed Culture Solid Substrate Fermentation of Cottonseed Meal

The objective of this work was to study the effect of mixed culture solid substrate fermentation of C. tropicalis ZD-3 with A. niger ZD-8 on detoxification of cottonseed meal (CSM), and to investigate the effect of fermentation period, proportion of CSM in substrate, sodium carbonate, minerals and heat treatment on the reduction of free gossypol levels during mixed culture solid substrate fermentation of CSM. Experiment 1: Three groups of disinfected CSM substrate were incubated for 48 h after inoculation with either of the fungi C. tropicalis ZD-3, A. niger ZD-8 or mixed culture (C. tropicalis ZD-3 with A. niger ZD-8). One non-inoculated group was used as the control. Levels of initial and final free gossypol (FG), CP and in vitro CP digestibility were assayed. The results indicated that mixed culture fermentation was far more effective than single strain fermentation, which not only had higher detoxification rate, but also had higher CP content and in vitro digestibility. Experiment 2: CSM substrates were treated according to experimental variables including fermentation period, proportion of CSM in substrate, sodium carbonate, minerals and heat treatment, Then, the treated CSM substrates were inoculated with mixed culture (C. tropicalis ZD-3 with A. niger ZD-8) and incubated at 30°C for 36 h in a 95% relative humidity chamber. After fermentation ended, FG and CP content of fermented CSM substrate was assayed. The results showed that the appropriate fermentation period was 36 h, and the optimal proportion of CSM in substrate was 70%. Addition of sodium carbonate to CSM substrate was beneficial for fermentative detoxification. Heat treatment could facilitate fermentative detoxification, and

Development of a microbial fermentation process for detoxification of gossypol in cottonseed meal

The objective was to study effects of selected fungi, carbohydrate sources, urea, heat treatment and minerals on the reduction of free gossypol (FG) levels during solid substrate fermentation of cottonseed meal (CSM), and to determine the crude protein (CP) and amino acid (AA) content as well as the in vitro digestible CP and AA of CSM substrate fermented under optimal conditions. Six groups of autoclaved CSM substrate were incubated for 48 h after inoculation with either of the fungi Candida capsuligena ZD-1, Candida tropicalis ZD-3, Saccharomyces cerevisae ZD-5, Aspergillus terricola ZD-6, Aspergillus oryzae ZD-7, or Aspergillus niger ZD-8. One non-inoculated group was the control. Levels of initial and final FG and CP were assayed. Results indicated that microbial fermentation could greatly decrease FG levels in CSM, but it differed among species of microorganisms with C. tropicalis ZD-3 the most effective. The CSM substrate was supplemented with carbohydrate sources, urea and minerals, and one group of non-autoclaved CSM substrate was used to investigate effects of heat treatment. The treated CSM substrates were inoculated with C. tropicalis ZD-3 and incubated for 24 or 48 h. Results showed that CSM substrate supplemented with starch and sucrose enhanced detoxification of gossypol, but heat treatment and minerals were also effective in reducing FG levels during solid substrate fermentation of CSM. The detoxification effect with minerals was the best among treatments.