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1.
Alginate encapsulation of an atoxigenic strain of Aspergillus flavus was studied in order to optimize encapsulation of fungal inocula with alginic acid. Sterilization by autoclaving is known to depolymerize sodium alginate. Buffered solutions (pH = 7-8) reduced this effect. Autoclaving the alginate solution with a filler/nutrient further inhibited the depolymerization reaction. Autoclaving under optimal conditions allowed a less expensive alginate (medium viscosity) to be used at a lower concentration (1%) to produce a stable product. The lowest cost pellets resulted from use of 1% medium viscosity sodium alginate with 10% cotton-seed meal. Further savings may be achieved by performing fermentations directly in alginate-nutrient mixtures and thus eliminating the mixing and blending steps. In such formulations, the nutrient composition and length of fermentation must be adjusted to prevent alginate hydrolysis. The ultimate composition of alginate pellets is influenced by the diffusion of nutrients during gelation. Up to 65% of water-soluble nutrients were lost from alginate pellets during gelation. Once pellets are introduced into the environment, organisms other than the formulated agent compete for pelleted nutrients. A minimum concentration of the biocontrol agent must be present to ensure the agent excludes competitors and successfully converts the nutrients to biomass. For A. flavus, 5000 spores g-1 were required. 相似文献
2.
A procedure was developed to encapsulate mycelia of an atoxigenic strain of Aspergillus flavus in alginate pellets for seeding into agricultural fields in order to reduce aflatoxin contamination via competitive exclusion. Kaolin, a clay filler commonly employed in alginate formulations, was detrimental to pellet performance as measured by spore yield. Corn cob grits, a by-product of the corn industry, was found to be an excellent replacement for kaolin. Of nine nutritive adjuvants tested, wheat gluten improved pellet performance the most, although gluten concentrations above 5% were difficult to process. The best formulation tested consisted of 1% sodium alginate, 5% corn cob grits and 5% wheat gluten. On a 'per gram' basis, this alginate formulation yielded more spores than either A. flavus sclerotia or colonized wheat seed. Pesticides were also tested as adjuvants with potential use for protecting pellets under field conditions. Only one (chloramphenicol) of four tested pesticides (the others were dichloran, rose Bengal and cyfluthrin) reduced pellet sporulation. Formulations with or without pesticide adjuvants retained similar spore yield potential during a 2-year storage at 8 C. However, spore production in stored products lagged behind that of fresh products. At 75% relative humidity (RH), pellet storage stability decreased with increasing temperature from 27 to 42 C. Pellet spore yield at 32 C decreased as RH decreased from 100 to 90%. Sporulation occurred at 90% RH but not at 88% RH. Spore yield varied widely in four field tests, and the cumulative spore yield was inversely correlated (r2= -0.798, P 0.01) with rainfall. The results suggest that alginate pellets may be effective formulations for delivery of atoxigenic A. flavus strains to furrow-irrigated cotton in desert environments, where aflatoxin contamination of cottonseed is most severe. 相似文献
3.
Ming Chang Shun-Gui Zhou Na Lu Jin-Ren Ni 《World journal of microbiology & biotechnology》2008,24(4):441-447
Production of Bacillus thuringiensis (Bt) based bioinsecticide was studied by using starch processing wastewater (SPW) as a raw material. Results indicated that
the nutrients contained in SPW were sufficient for growth, sporulation and δ-endotoxin production of Bacillus
thuringiensis subsp. kurstaki (Btk). The final cell counts and spore counts achieved in SPW medium were 72% and 107% respectively higher than those in
the soybean meal based commercial medium. Higher δ-endotoxin yield of 2.67 mg mL−1 and higher entomotoxicity of 1,050 IU μL−1 were also obtained in SPW medium as compared with the commercial medium at the end of fermentation. The morphological observations
also revealed that the fermentation cycle of Btk could be shortened in this new medium. This process provides solutions for
safe SPW disposal and production of high potency and low cost bioinsecticide. 相似文献
4.
Thermomucor indicae-seudaticae was immobilized in alginate, κ-carrageenan, agarose, agar, polyacrylamide and loofah (Luffa cylindrica) sponge (as such or coated with alginate/starch/Emerson YpSs agar), and used for the production of glucoamylase in submerged
fermentation. The mycelium developed from alginate-immobilized sporangiospores secreted higher glucoamylase titres (22.7 U ml−1) than those immobilized in other gel matrices and the freely growing mycelial pellets (18.5 U ml−1). Loofah network provided a good support for mycelial growth, but the enzyme production was lower than that attained with
alginate beads. Glucoamylase production increased with inoculum density and the optimum levels were achieved when 40 calcium
alginate beads (∼5 × 106 immobilized spores) were used to inoculate 50 ml production medium. The alginate bead inoculum displayed high storage stability
at 4°C and produced comparable enzyme titres up to 120 days. The glucoamylase production by hyphae emerged from the immobilized
sporangiospores was almost stable over eight batches of repeated fermentation. Scanning electron micrographs of alginate beads,
after batch fermentation, revealed extensive mycelial growth inside and around the beads. 相似文献
5.
In the laboratory, the white rot fungus Phanerochaete
chrysosporium degrades numerous organic pollutants. Lack of a
slow-release delivery system to toxic waste sites, for this and other fungi,
however, constitutes an important barrier to practical implementation. In
this study, the use of calcium alginate as an encapsulant for mycelia was
investigated; samples were in the form of pellets 1–3 mm in diameter. When
refrigerated, alginate-embedded mycelia of P. chrysosporium were
viable for one year, both with and without nutrient supplementation. At room
temperature, in the absence of nutrient supplementation, viability decreased
sharply within 2 months. Addition of sawdust or corncob grits extended the
viability of alginate-embedded mycelia; nevertheless, after 9 months only
about 20% of the pellets stored at room temperature yielded fungal
growth. Spores of P. chrysosporium, embedded in alginate pellets
together with corncob grits, gave 75% viability after 9 months of
storage at room temperature. Alginate-embedded mycelia were used in Petri
plate toxicity tests with 2,4,6-trinitrotoluene (TNT) and gave more rapid and
reproducible results than tests performed with mycelial plugs. These
experiments demonstrated the feasibility of encapsulating P.
chrysosporium in calcium alginate pellets, thus providing a potential
method of delivering white rot fungi to toxic waste sites, as well as for
developing a system of standardized toxicity testing in plate assays.
Received: 10 July 1996 / Accepted: 13 August 1996 相似文献
6.
[目的]探究少根根霉不同生态环境、不同地理位置、不同产孢能力和不同分类学变种的发酵产物多样性及相关性,为工业生产提供指导.[方法]代表性的68株少根根霉菌株于糯米培养基中进行液态发酵,利用高效液相色谱法测定各种发酵产物浓度,计算发酵产物间的Pearson相关系数,通过多因素方差分析和主成分分析解析各类菌株与发酵特性的相... 相似文献
7.
The growth, morphology, alginate yield and composition of Undaria pinnatifidawas studied from March to August in 2000 and 2001 at the northern limit of distribution of the species in Peter the Great
Bay, the Sea of Japan (Russia). The changes in morphology, alginate yield and composition were caused by sporophyte growth
and sporulation. The average rate of biomass change was 2–5% d−1. The highest alginate content (51% d.wt) was obtained from blades, with lower values for sporophylls and midribs. An increase
in alginate content was detected before sporulation. The conditions seem favourable for farming the alga in this region, with
June the optimum month for harvesting.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
The morphological type of a microorganism generally influences its metabolite production. In the present study, we investigated
the effects of the mycelial morphology of shiitake (Lentinula edodes) on the production of 2-mercaptohistidine trimethylbetaine (ergothioneine, ESH) during liquid fermentation. Analyses of the
distribution of ESH in mycelial cells of different morphological types revealed that the ESH content of pellets obtained from
the liquid fermentation media was much greater than the content in the free mycelia and clumps. The concentration of ESH in
pellets on day 15 of liquid fermentation reached 0.79 mg/g dry weight (DW), which is approximately three times the concentration
found in mycelia clumps (0.28 mg/g DW) and free mycelia (0.31 mg/g DW). Macroscopic image analysis of the development and
morphological changes of the pellets during a liquid fermentation period of up to 25 days indicated that pellet growth showed
a highly positive correlation with the increase in ESH concentration (r
2 = 0.9851). A reduced agitation rate of 50 rpm for the culture medium was suitable for pellet formation and size enlargement.
The results obtained in this work would be helpful in guiding the intentional manipulation of the distribution and enrichment
of ESH in L. edodes through changes in liquid fermentation conditions. 相似文献
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Summary Mycelia of Claviceps purpurea CBS 164.59 were immobilized in 2%, 4%, and 8% calcium alginate. Alkaloid production by free cells declined after 60 days, while immobilized cells retained their activity for 200 days. The cumulative alkaloid production for all fermentation cycles using 8% calcium alginate immobilized mycelia was 25 times higher than that from free cells. The best yields of the ergopeptide ergometrine were reached with 4% gel immobilized mycelia, while higher gel concentrations caused a shift in the alkaloid biosynthesis towards high clavine alkaloid production.Beginning with the third cycle of reincubation the immobilized mycelia showed a marked tendency to fragmentize into vacuolated arthrosporoid-like structures and produced violet-black pigments so that the beads recalled sclerotial structures of parasitically living Claviceps.Dedicated to Prof. Dr. K. Esser to his 60th birthday 相似文献
12.
【背景】粗糙链霉菌(Streptomyces scabrisporus) HBERC-53204是本中心自主分离的一株链霉菌,经鉴定,其产生一种活性化合物司替霉素B (steffimycin B,SMB),对多种动植物重要病原菌具有良好生物活性。【目的】提高SMB发酵水平,拓宽放线菌活性天然产物在农牧业领域的研究及应用。【方法】以本实验室筛选出的一株产SMB的粗糙链霉菌HBERC-53204为研究对象,运用单因素试验筛选培养基的主效碳源、氮源、无机盐及各营养成分最适浓度,并基于单因素试验结果,通过Plackett-Burman(PB)试验设计筛选出显著影响因素,再结合最陡爬坡试验、Box-Behnken (BB)响应面法拟合显著因子与产量的非线性方程求解,进一步优化菌株产SMB的最佳发酵培养基配方。【结果】优化后最佳培养基配方为:葡萄糖36.22 g/L,蛋白胨8.00 g/L,酵母粉8.51 g/L,酸水解酪蛋白1.50 g/L,MgSO4 0.68 g/L,KNO3 1.00 g/L。经摇瓶验证,优化后SMB效价达到477.26 mg/L... 相似文献
13.
Anne Grundschober Florian M. Freimoser Urs Tuor Markus Aebi 《Microbiological research》2001,156(3):247
Capilliconidia, the asexual secondary spores of Neozygites parvispora (Zygomycetes, Entomophthorales) were produced in vitro either by entrapment of vegetative cells (hyphal bodies) in alginate pellets or after plating them onto water agar. Cultivation of the fungus for 3 days in a medium lacking hemolymph increased spore production 30 to 40-fold, and about 10% of the cells produced capilliconidia. The in vitro produced capilliconidia were infectious to Thrips tabaci and the fungus was reisolated from infected insects, thus completing its asexual life cycle under laboratory conditions. A decrease in capilliconidia production and a modification of the number of nuclei per spore were observed for isolates cultivated in vitro for more than 2 months, but subsequent host passages restored and increased sporulation efficiency without influencing the number of nuclei. Fungal cultures were stored at —80 °C for up to 7 months, and the capability to sporulate and infect T. tabaci was preserved. A bioassay procedure for infecting T. tabaci with N. parvispora is described, the first mycosed insects dying usually after 8 d of incubation. 相似文献
14.
To determine the effect of tryptophan and pH on sporulation of Coniothyrium minitans, the fungus was cultivated using a two-stage, agar plate method in which addition of tryptophan and pH were controlled at
the sporulation stage. The spore yield was enhanced by 4 times with 0.1 g tryptophan/l addition after 72 h. The optimal pH
values were 4 for mycelia growth and 5.8–6 for sporulation. Mycelia grown at pH 6 had a higher productivity of spore production
than did those grown at pH 4. 相似文献
15.
【背景】尖孢镰孢(Fusariumoxysporum)引起的烟草根腐病在世界烟区普遍发生,严重影响烟草产量和质量,化学农药无法有效防治病害,利用生防菌防治该病成为研究热点。【目的】明确贝莱斯芽孢杆菌(Bacillusvelenzensis)GDND-2对尖孢镰孢生长发育的抑制作用。【方法】制备含10%和20%GDND-2发酵滤液的PDA培养基,涂在玻片上,接种尖孢镰孢分生孢子,观察滤液对尖孢镰孢孢子萌发、菌丝生长、孢子形成和色素产生的影响,应用扫描和透射电镜观察菌体超微结构的变化。【结果】贝莱斯芽孢杆菌GDND-2发酵滤液延迟孢子萌发2h以上,造成芽管膨大畸形,促使菌丝提早分枝,抑制菌丝延伸,使菌丝产生畸形球状结构,10%和20%发酵滤液对菌丝生长抑制率达53.41%和61.58%。滤液延迟病菌产孢,显著抑制产孢量,影响孢子形态,刺激病菌产生色素。10%和20%发酵滤液延迟产孢20h和28h,对产孢量的抑制率为52.11%和78.85%,滤液促使病菌形成小型分生孢子。观察尖孢镰孢的超微结构,部分菌丝膨大、畸形,细胞壁变薄,细胞膜消失,细胞质渗出,胞内呈空腔结构;部分菌丝严重皱缩、扭曲、... 相似文献
16.
Fusarium oxysporum Schlecht. f.sp. orthoceras (Appel & Wollenw.) Bilai, a potential biocontrol agent against Orobanche cumana Wallr.,was formulated into two granular forms, wheatflour kaolin (`Pesta') granules and sodium alginatepellets. The formulations were compared in terms ofeffectiveness for mitigating O. cumanaparasitism in sunflower and shelf-life forstorage. `Pesta' granules reduced the emergence of O. cumana shoots by 64% while sodium alginatepellets did not reduce the emergence rate but increased thepercentage of diseased O. cumana plants.Calculated efficacy of the application was better for`Pesta' granules. Viability of the formulatedmaterial tested in the laboratory was higher in sodium alginatepellets than in the `Pesta' formulation.However, a loss of virulence after six months of storage wasalso observed in sodium alginate pellets in agreenhouse experiment. 相似文献
17.
D. B. Archer D. A. MacKenzie M. J. Ridout 《Applied microbiology and biotechnology》1995,44(1-2):157-160
The secreted production of a heterologous enzyme, hen egg-white lysozyme, by Aspergillus niger was studied in shake flasks containing media of different initial viscosities. Raising the viscosity of the medium by addition of polyvinylpyrrolidone (PVP) brought about a transition in the form of growth from aggregated mycelia (pellets) to dispersed mycelia. The specific yield of lysozyme in cultures containing an initial concentration of 5% (w/v) starch was 8 mg lysozyme/g dry weight. Addition of 2% (w/v) PVP to the medium resulted in a specific yield of 14 mg lysozyme/g dry weight. 相似文献
18.
Summary Mycelia of Streptomyces sp. T 59-235 and Streptomyces tendae Tü 901 (producing the antibiotics tylosin and nikkomycin, resp.) were immobilized in different carriers. With both organisms best antibiotic production was observed in calcium alginate gel.Influence of aeration, cell density and flow rate on antibiotic production was investigated in batch fermentation and in a continuous system (air-bubbled reactor).In batch fermentation, immobilization prolongued the production phase from 72 to 120 h (Streptomyces T 59-235) and from 72 to 96 h (S. tendae). The relative productivity of immobilized cells was 40 to 50% compared to that of free mycelia in both cases.In continuous tylosin fermentation highest production rate was observed in a medium nearly saturated with oxygen.Nikkomycin production by immobilized S. tendae could be maintained for longer than 350 h in a continuous system. The production rate depended on cell density and flow rate of the medium. The maximum specific productivity was 100% compared to that of free mycelium in batch culture. 相似文献
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A. K. Singh M. Sharma R. Varshney S. S. Agarwal K. C. Bansal 《In vitro cellular & developmental biology. Plant》2006,42(2):109-113
Summary A method was developed for plant regeneration from alginate-encapsulated shoot tips of Phyllanthus amarus. Shoot tips excised from in vitro proliferated shoots were encapsulated in calcium alginate beads. The best gel complexation was achieved using 3% sodium alginate
and 75 mM CaCl2·2H2O. Maximum percentage response for conversion of encapsulated shoot tips into plantlets was 90% after 5 wk of culture on Murashige
and Skoog (MS) medium without plant growth regulator. The regrowth ability of encapsulated shoot tips was affected by the
concentration of sodium alginate, storage duration, and the presence or absence of MS nutrients in calcium alginate beads.
Plantlets with well-developed shoot and roots were transferred to pots containing an autoclaved mixture of soilrite and peat
moss (1∶1). The conversion of encapsulated shoot tips into plantlets also occurred when calcium alginate beads were directly
sown in autoclaved soilrite moistened with 1/4-MS salts. Encapsulation of vegetative propagules in calcium alginate beads
can be used as an alternative to synthetic seeds derived from somatic embryos. 相似文献