Polyurethane foam as an inert carrier for the production of L(+)-lactic acid by Lactobacillus casei under solid-state fermentation

AIM: Production of L-lactic acid in solid-state fermentation (SSF) using polyurethane foam (PUF) as inert support moistened with cassava bagasse starch hydrolysate. METHODS AND RESULTS: PUF impregnated with cassava bagasse starch hydrolysate as major carbon source was used for the production of L-lactic acid using Lactobacillus casei in solid-state condition. The key parameters such as reducing sugar, inoculum size and nutrient mixture were optimized by statistical approach using response surface methodology. More than 95% conversion of sugars to lactic acid from 4 g reducing sugar per gram dry support was attained after 72 h when the inert substrate was moistened with 6.5 ml of nutrient solution and inoculated with 1.5 x 10(9) CFU of L. casei. While considering the lactate yield based on the solid support used, a very high yield of 3.88 g lactic acid per gram PUF was achieved. CONCLUSION: PUF acted as an excellent inert support for L. casei and provided a platform for the utilization of starchy waste hydrolysate in a lower reactor volume. SIGNIFICANCE AND IMPACT OF THE STUDY: This is a cost effective cultivation of lactic acid bacteria for producing lactic acid from agro based waste products such as cassava bagasse. This is the first report on the exploitation of PUF as an inert support for lactate production under SSF.     

A comparison of the production of ethanol between simultaneous saccharification and fermentation and separate hydrolysis and fermentation using unpretreated cassava pulp and enzyme cocktail

The processes of separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) were employed using Saccharomyces cerevisiae for the production of ethanol from cassava pulp without any pretreatment. A combination of amylase, cellulase, cellobiase, and glucoamylase produced the highest levels of ethanol production in both the SHF and the SSF method. A temperature of 37 °C, a pH of 5.0, and an inoculum size of 6% were the optimum conditions for SSF. For the batch process at a pulp concentration of 20%, ethanol production levels from SHF and SSF were the highest, at 23.51 and 34.67 g L(-1) respectively, but in the fed-batch process, the levels of ethanol production from SHF and SSF rose to 29.39 and 43.25 g L(-1) respectively, which were 25% and 24.7% higher than those of the batch process. Thus SSF using the fed-batch provided a more efficient method for the utilization of cassava pulp.     

木薯粉同步糖化发酵(SSF)产丁二酸

【目的】通过优化产琥珀酸放线杆菌GXAS137同步糖化发酵木薯粉产丁二酸的发酵培养基,提高丁二酸产量,降低生产成本。【方法】在单因素试验的基础上,先利用Plackett-Burman试验设计筛选出影响丁二酸发酵的重要参数,再采用正交试验确定重要参数的最佳水平。【结果】价格低廉玉米浆可用作氮源,影响丁二酸产量的重要参数是木薯粉、玉米浆、碱式碳酸镁和糖化酶浓度。最佳条件为(g/L):木薯粉100,玉米浆14,糖化酶2.0 AGU/g底物,碱式碳酸镁75。优化后丁二酸产量达到69.31 g/L,丁二酸得率为90.01%,生产强度为1.44 g/(L·h)。与初始条件(52.34 g/L)相比,丁二酸浓度提高了32.42%。并利用1.3 L发酵罐对SSF与SHF两种发酵工艺进行了比较,SSF丁二酸产量(72.21 g/L)远高于SHF(56.86 g/L)。【结论】产琥珀酸放线杆菌同步糖化发酵木薯粉丁二酸产量高,生产成本低,具有较好的工业化应用前景。     

Biodegradation of shrimp processing bio-waste and concomitant production of chitinase enzyme and N-acetyl-D-glucosamine by marine bacteria: production and process optimization

A total of 250 chitinolytic bacteria from 68 different marine samples were screened employing enrichment method that utilized native chitin as the sole carbon source. After thorough screening, five bacteria were selected as potential cultures and identified as; Stenotrophomonas sp. (CFR221?M), Vibrio sp. (CFR173?M), Phyllobacteriaceae sp. (CFR16?M), Bacillus badius (CFR198?M) and Bacillus sp. (CFR188?M). All five strains produced extracellular chitinase and GlcNAc in SSF using shrimp bio-waste. Scanning electron microscopy confirmed the ability of these marine bacteria to adsorb onto solid shrimp bio-waste and to degrade chitin microfibers. HPLC analysis of the SSF extract also confirmed presence of 36-65?% GlcNAc as a product of the degradation. The concomitant production of chitinase and GlcNAc by all five strains under SSF using shrimp bio-waste as the solid substrate was optimized by 'one factor at a time' approach. Among the strains, Vibrio sp. CFR173?M produced significantly higher yields of chitinase (4.8 U/g initial dry substrate) and GlcNAc (4.7?μmol/g initial dry substrate) as compared to other cultures tested. A statistically designed experiment was applied to evaluate the interaction of variables in the biodegradation of shrimp bio-waste and concomitant production of chitinase and GlcNAc by Vibrio sp. CFR173?M. Statistical optimization resulted in a twofold increase of chitinase, and a 9.1 fold increase of GlcNAc production. These results indicated the potential of chitinolytic marine bacteria for the reclamation of shrimp bio-waste, as well as the potential for economic production of chitinase and GlcNAc employing SSF using shrimp bio-waste as an ideal substrate.     

Enhanced production of raw starch degrading enzyme using agro-industrial waste mixtures by thermotolerant Rhizopus microsporus for raw cassava chip saccharification in ethanol production

In the present study, solid-state fermentation for the production of raw starch degrading enzyme was investigated by thermotolerant Rhizopus microsporus TISTR 3531 using a combination of agro-industrial wastes as substrates. The obtained crude enzyme was applied for hydrolysis of raw cassava starch and chips at low temperature and subjected to nonsterile ethanol production using raw cassava chips. The agro-industrial waste ratio was optimized using a simplex axial mixture design. The results showed that the substrate mixture consisting of rice bran:corncob:cassava bagasse at 8?g:10?g:2?g yielded the highest enzyme production of 201.6?U/g dry solid. The optimized condition for solid-state fermentation was found as 65% initial moisture content, 35°C, initial pH of 6.0, and 5?×?10⁶ spores/mL inoculum, which gave the highest enzyme activity of 389.5?U/g dry solid. The enzyme showed high efficiency on saccharification of raw cassava starch and chips with synergistic activities of commercial α-amylase at 50°C, which promotes low-temperature bioethanol production. A high ethanol concentration of 102.2?g/L with 78% fermentation efficiency was achieved from modified simultaneous saccharification and fermentation using cofermentation of the enzymatic hydrolysate of 300?g raw cassava chips/L with cane molasses.     

Tamarind seed powder and palm kernel cake: two novel agro residues for the production of tannase under solid state fermentation by Aspergillus niger ATCC 16620

Palm kernel cake (PKC), the residue obtained after extraction of palm oil from oil palm seeds and tamarind seed powder (TSP) obtained after removing the fruit pulp from tamarind fruit pod were tested for the production of tannase under solid-state fermentation (SSF) using Aspergillus niger ATCC 16620. The fungal strain was grown on the substrates without any pretreatment. In PKC medium, a maximum enzyme yield of 13.03 IU/g dry substrate (gds) was obtained when SSF was carried out at 30 degrees C, 53.5% initial substrate moisture, 33 x 10(9) spores/5 g substrate inoculum size and 5% tannic acid as additional carbon source after 96 h of fermentation. In TSP medium, maximum tannase yield of 6.44 IU/gds was obtained at 30 degrees C, 65.75% initial substrate moisture, 11 x 10(9) spores/5 g substrate inoculum, 1% glycerol as additional carbon source and 1% potassium nitrate as additional nitrogen source after 120 h of fermentation. Results from the study are promising for the economic utilization and value addition of these important agro residues, which are abundantly available in many tropical and subtropical countries.     

Conventional process for ethanol production from Indian broken rice and pearl millet

A conventional process for ethanol production involving liquefaction followed by simultaneous saccharification and fermentation (SSF) under the yeast fermentation conditions, was investigated at 30 and 35% dry solid (DS) of Indian broken rice and pearl millet feedstocks. The study followed the typical conventional process currently in use by the Indian Ethanol Industry. Liquefaction was carried out using a thermostable alpha amylase, and whereas SSF with a glucoamylase with additional side activities of pullulanase and protease under the yeast fermentation conditions. To measure the enzyme efficacy in the liquefaction process, fermentable sugar and liquefact solubility (brix) were monitored at the end of the liquefaction process. The liquefact was subjected to SSF with yeast. Addition of an acid fungal protease at a concentration of 0.1?kg per metric ton of grain during SSF was observed to accelerate yeast growth and ultimately, ethanol yield with both feedstocks. With both concentrations of feedstocks, the fermentation efficiency and ethanol recovery were determined. This study assesses the potential of these enzymes for ethanol production with higher dry solid concentration (≥30% w/w DS) of both these feedstocks in the conventional process to achieve higher plant throughput without compromising fermentation efficiency and ethanol recovery.     

Solid-state fermentation for Trichokonins production from Trichoderma koningii SMF2 and preparative purification of Trichokonin VI by a simple protocol

Trichokonins are peptaibols produced by Trichoderma koningii SMF2. The main isoforms are Trichokonin VI, Trichokonin VII and Trichokonin VIII. The solid-state fermentation (SSF) was applied for the production of Trichokonin VI. The fermentation factors, which included inoculum size, incubation temperature, initial moisture content and initial pH, were investigated and optimized by response surface methodology. The maximum Trichokonin VI production (4.07mg/g dry substrate) was achieved by employing inoculum size of 18%, incubation temperature at 24.3 degrees C, initial moisture content of 77.5% and initial pH at 5.0. Furthermore, gel filtration and preparative HPLC were used for separation of Trichokonin VI from a crude extract of the T. koningii SMF2 culture. With this preparative purification protocol under optimized fermentation conditions, 146.20mg Trichokonin VI was obtained from 1kg solid cultures. It has been shown that the obtained Trichokonin VI is more than 95% in purity. This is the first report on optimization of peptaibols production in SSF with high content. An efficient method for the preparative purification of Trichokonin VI is also proposed.     

Relation between Citric Acid Production and Respiration Rate of Aspergillus niger in Solid‐State Fermentation

Among the organic acids produced industrially, citric acid is the most important in quantitative terms. Solid‐state fermentation (SSF) has been an alternative method for citric acid production using agro‐industrial residues such as cassava bagasse (CB). The use of CB as a substrate can avoid environmental problems caused by its disposal into the environment. This study was developed to verify the influence of the treated bagasse amount, and consequently, the influence of the gelatinization degree of CB starch on citric acid production by SSF in Erlenmeyer flasks, horizontal drums, and trays. The best results were obtained in a horizontal drum bioreactor using 100 % of treated CB. However, trays showed advantages and good perspectives for large‐scale citric acid production due to economic reasons such as energy costs. A kinetic study was also carried out in order to compare citric acid production in glass columns (laboratory scale) and horizontal drum bioreactors (semi‐pilot scale). This study was accomplished in order to follow the influence of aeration on citric acid accumulation. In addition, the production of CO₂ was evaluated as an indirect method of biomass estimation. Citric acid production was higher in glass columns (309.70 g/kg of dry CB) than in HD bioreactors (268.94 g/kg of dry CB). Finally, it was possible to show that citric acid production was favored by a limited biomass production, which occurred with low aeration rates. Biomass production is related to CO₂ production and as a result, a respirometry analysis could be used for biomass estimation.     

Production of multiple extracellular enzyme activities by novel submerged culture of <Emphasis Type="Italic">Aspergillus kawachii</Emphasis> for ethanol production from raw cassava flour

Cassava is a starch-containing root crop that is widely used as a raw material in a variety of industrial applications, most recently in the production of fuel ethanol. In the present study, ethanol production from raw (uncooked) cassava flour by simultaneous saccharification and fermentation (SSF) using a preparation consisting of multiple enzyme activities from Aspergillus kawachii FS005 was investigated. The multi-activity preparation was obtained from a novel submerged fermentation broth of A. kawachii FS005 grown on unmilled crude barley as a carbon source. The preparation was found to consist of glucoamylase, acid-stable α-amylase, acid carboxypeptidase, acid protease, cellulase and xylanase activities, and exhibited glucose and free amino nitrogen (FAN) production rates of 37.7 and 118.7 mg/l/h, respectively, during A. kawachii FS005-mediated saccharification of uncooked raw cassava flour. Ethanol production from 18.2% (w/v) dry uncooked solids of raw cassava flour by SSF with the multi-activity enzyme preparation yielded 9.0% (v/v) of ethanol and 92.3% fermentation efficiency. A feasibility study for ethanol production by SSF with a two-step mash using raw cassava flour and the multi-activity enzyme preparation manufactured on-site was verified on a pilot plant scale. The enzyme preparation obtained from the A. kawachii FS005 culture broth exhibited glucose and FAN production rates of 41.1 and 135.5 mg/l/h, respectively. SSF performed in a mash volume of about 1,612 l containing 20.6% (w/v) dry raw cassava solids and 106 l of on-site manufactured A. kawachii FS005 culture broth yielded 10.3% (v/v) ethanol and a fermentation efficiency of 92.7%.     

A process for protein enrichment of cassava by solid substrate fermentation in rural conditions

An artisanal static process for protein enrichment of cassava by solid-state fermentation, developed in laboratory and tested on pilot units in Burundi (Central Africa), provides enriched cassava containing 10.7% of dry matter protein versus 1% before fermentation. Cassava chips, processed into granules of 2-4-mm diameter, are moistened (40% water content) and steamed. After cooling to 40 degrees C, cassava is mixed with a nutritive solution containing the inoculum (Rhizopus oryzae, strain MUCL 28627) and providing the following per 100 g dry matter: 3.4 g urea, 1.5 g KH(2)PO(4), 0.8 g MgSO(4).7H(2)O, and 22.7 g citric acid. For the fermentation, cassava, with ca. 60% moisture content, is spread in a thin layer (2-3 cm thick) on perforated trays and slid into an aerated humidified enclosure. The incubation lasts +/- 65 h. The production of protein enriched cassava is 3.26 kg dry matter/m(2) tray. The effects of the variation of the nutritive solution composition and the inoculum conservation period on the protein production are equally discussed.     

Production of tannase by solid-state fermentation

An attempt has been made to optimize the production of enzyme tannase by solid state fermentation (SSF) using the organism Rhizopus oryzae. The best favourable conditions for enzyme production include initial pH 5 with 4 days of incubation period at 40°C and 72% humidity, and 10 g wheat bran soaked in 2.5% tannic acid.     

Kinetics of Gibberella fujikuroi growth and gibberellic acid production by solid-state fermentation in a packed-bed column bioreactor

In this work the growth of Gibberella fujikuroi and gibberellic acid (GA3) production were studied using coffee husk and cassava bagasse as substrates in a packed-bed column bioreactor connected to a gas chromatograph for exit gas analysis. With the respirometric data, a logarithmic correlation between accumulated CO2 and biomass production was determined, and the kinetics of the fungal growth was compared for estimated and experimental data. The solid medium consisted of coffee husk (pretreated with alkali solution), mixed with cassava bagasse (7:3 dry weight basis), with a substrate initial pH of 5.2 and moisture of 77%. Cultivation was carried out in glass columns, which were packed with preinoculated substrate and with forced aeration of 0.24 L of air/[h (g of substrate)] for the first 3 days, and 0.72 L of air/[h (g of substrate)] for the remaining period. The maximum specific growth rate (microm) obtained was 0.052 h(-1) (between 24 and 48 h of fermentation). A production of 0.925 g of GA3/kg of substrate was achieved after 6 days of fermentation.     

Bioethanol from fermentation of cassava pulp in a fibrous-bed bioreactor using immobilized Δldh, a genetically engineered Thermoanaerobacterium aotearoense

There is an increasing worldwide interest in bioethanol production from agricultural, industrial, and urban residues for both ecological and economic reasons. The acid hydrolysis of cassava pulp to reducing sugars and their fermentation to ethanol were evaluated in a fibrousbed bioreactor with immobilized Δldh, a genetically engineered Thermoanaerobacterium aotearoense. A maximum yield of total reducing sugars of 53.5% was obtained after 8 h of hydrolysis at 85oC in 0.4 mol/L hydrochloric acid with a solid-to-liquid ratio of 1:20, which was optimized by using an orthogonal design based on preliminary experiments. In the FBB, the fed-batch fermentation, using glucose as the sole carbon source, gave a maximum ethanol production of 38.3 g/L with a yield of 0.364 g/g in 100 h; whereas the fed-batch fermentation, using xylose as the sole carbon source, gave 34.1 g/L ethanol with a yield of 0.342 g/g in 135 h. When cassava pulp hydrolysate was used as a carbon source, 39.1 g/L ethanol with a yield of 0.123 g/g cassava pulp in185 h was observed, using the fed-batch fermentation model. In addition, for repeated batch fermentation of cassava pulp hydrolysate carried out in the fibrous-bed bioreactor, long-term operation with high ethanol yield and volumetric productivity were achieved. The above results show that the acid hydrolysate of cassava pulp can be used for ethanol production in a fibrous-bed bioreactor, although some inhibition phenomena were observed during the process of fermentation.     

毛壳霉CQ31的鉴定及固体发酵产木聚糖酶条件的优化

从土壤中筛选出一株产木聚糖酶的真菌CQ31, 经鉴定后命名为毛壳霉CQ31。该菌能够利用几种农业废弃物固体发酵高产木聚糖酶, 玉米杆为最佳碳源。单因素优化试验表明: 以玉米杆为碳源, 胰蛋白胨为氮源, 初始水分含量80%, 初始pH值9.0为最佳产酶条件。在优化后的条件下培养7 d产木聚糖酶水平高达4897 U/g干基碳源, 此时甘露聚糖酶酶活达803 U/g干基碳源。因此, 毛壳霉CQ31固体发酵产木聚糖酶和甘露聚糖酶具有一定的工业化应用前景。     

Single cell oil production in solid-state fermentation by Microsphaeropsis sp. from steam-exploded wheat straw mixed with wheat bran

Microsphaeropsis sp. was used to produce SCO in solid-state fermentation (SSF) from a substrate consisting of steam-exploded wheat straw (SEWS) and wheat bran (WB). The yield of SCO was 42 mg/g dry substrate (gds) without adding cellulase. To achieve a higher SCO yield, cellulase was added to the solid-state medium, resulting in an increase of SCO from 42 to 74 mg/gds with a cellulase loading of 10 FPU/gds. Other SSF parameters such as ratio of SEWS to WB of the dry substrate, initial moisture content, and incubation temperature were optimized under the condition of cellulase loading of 10 FPU/gds. So optimized, the SCO yield was 80 mg/gds, and the SCO content of the dry fermented mass was 10.2%. This research explored a novel method to produce SCO from the abundant and cheap agricultural residues - wheat straw and wheat bran.     

Conidia production ofBeauveria sp. by solid-state fermentation for biocontrol ofIlex paraguariensis caterpillars

Conidia production of Beauveria sp. strain LAG by solid-state fermentation (SSF) using blends of agro-industrial residues (residual potatoes and sugar-cane bagasse) was optimized with respect to cultivation conditions and the composition of substrate mixture in Erlenmeyer flasks and column-type bioreactor. With a blend of 60 % residual potatoes and 40 % sugar-cane bagasse the optimum conditions achieved were: incubation temperature 26 degrees C, initial substrate pH 6, inoculum concentration 10(7) conidia per g substrate; optimal initial moisture of the substrate was 70 % for Erlenmeyer flasks, in column-type bioreactor (with forced aeration) the optimal initial moisture of the substrate was 65 % with airflow of 60 mL/min. The highest production (1.07 x 10(10) conidia per g dry substrate) was achieved after a 10-d fermentation. The conidia were used in laboratory assays against Thelosia camina and Hylesia sp., caterpillars that are serious pests of mate plants. The mortality of T. camina was >90 % 10 d after spraying caterpillars with 1 mL conidia suspension at a concentration 10(5)-10(8)/mL. For Hylesia sp., the mortality was 70 %, 7 d after immersion in the conidia suspension containing 108 conidia per mL. Therefore, the Beauveria sp. LAG can be considered to be an important biocontrol instrument in the prospect of the Integrated Pest Management for mate plants.     

Solid-state fermentation for the production of Monascus pigments from jackfruit seed

The aim of the present work was to investigate the feasibility of jackfruit seed powder as a substrate for the production of pigments by Monascus purpureus in solid-state fermentation (SSF). A pigment yield of 25ODUnits/g dry fermented substrate was achieved by employing jackfruit seed powder with optimized process parameters such as 50% initial moisture content, incubation temperature 30 degrees C, 9x10(4)spores/g dry substrate inoculum and an incubation period of seven days. The color of the pigments was stable over a wide range of pH, apparently due to the buffering nature of the substrate, which could be a significant point for its scope in food applications. To the best of our knowledge this is the first report on pigment production using jackfruit seed powder in solid-state fermentation (SSF).     

Production of tannase by Aspergillus niger Aa-20 in submerged and solid-state fermentation: influence of glucose and tannic acid

Tannase production by Aspergillus niger Aa-20 was studied in submerged (SmF) and solid-state (SSF) fermentation systems with different tannic acid and glucose concentrations. Tannase activity and productivity were at least 2.5 times higher in SSF than in SmF. Addition of high tannic acid concentrations increased total tannase activity in SSF, while in SmF it was decreased. In SmF, total tannase activity increased from 0.57 to 1.03 IU/mL, when the initial glucose concentration increased from 6.25 to 25 g/L, but a strong catabolite repression of tannase synthesis was observed in SmF when an initial glucose concentration of 50 g/L was used. In SSF, maximal values of total tannase activity decreased from 7.79 to 2.51 IU when the initial glucose concentration was increased from 6.25 to 200 g/L. Kinetic results on tannase production indicate that low tannase activity titers in SmF could be associated to an enzyme degradation process which is not present in SSF. Tannase titers produced by A. niger Aa-20 are fermentation system-dependent, favoring SSF over SmF. Journal of Industrial Microbiology & Biotechnology (2001) 26, 296–302. Received 07 July 2000/ Accepted in revised form 15 February 2001