在糖化酶发酵生产中低温保存黑曲霉菌

在糖化酶生产过程中,为了防止正常生产中黑曲霉菌种性能的变化,对菌种的一级种母进行甘油冷冻保存,在-120℃的条件下分别保存30、60、90d,然后直接接入种母培养基,待成熟后接入种子罐,投入50t发酵罐工业生产,150h左右发酵结束。产酶单位与原工艺条件相一致。     

Investigation of the use of ram horn hydrolysate for fungal protein production

Production of the fungus Aspergillus niger NRRL 330 was studied in submerged fermentation with ram horn hydrolysate (RHH) as substrate. The characteristics of RHH have been reported previously. The RHH was enriched by addition of glucose and KH₂PO₄. The effects of kinetic parameters on the biomass yield of the fungus were investigated. The optimal conditions for growth of A niger on RHH were initial pH 6.5, temperature 30 °C, fermentation time 96 h and agitation speed 150 rpm. Under these optimal conditions the initial carbohydrate content of RHH was reduced from 1.52 to 0.2% and the biomass yield was 8.9 g l^?1. The biomass contained about 48.1% protein, 5.2% fat and 9.4% ash (on a dry weight basis). The amino acid content of the biomass was compared with Food and Agricultural Organisation (FAO) and animal feed standards. The protein produced contained all the essential amino acids for animal feed, but the amounts of these amino acids were somewhat lower than those of FAO and soybean reference protein. However, the amino acid composition of the biomass was better than that of animal feed. The results with RHH were also compared with previously reported data on fungal mycelium grown on waste liquor substrate. In conclusion, it was found that RHH could be used as a substrate in the production of fungal protein for use as animal feed. Copyright © 2003 Society of Chemical Industry     

Breaking of structural dormancy in seeds of Tetrapleura tetraptera by Aspergillus niger

Aspergillus niger (strain UUF9202) significantly reduced the dormancy period and boosted aggregate germination percentage (AGP) in seeds of Tetrapleura tetraptera. A net reduction in mean germination time (MGT) to 12 days and an increase from 0 to 42% AGP were obtained in 32 days. The optimal spore inoculum of the fungus was 8.5 × 10≥10 ml^?1 per 100 seeds in 96 h pregermination incubation. The potential of some physical factors in combination with this fungal concentration in enhancing AGP was evaluated. The treatments were as follows: (i) hot water scarification at 30°C, 50°C, 80°C and 100°C plus A niger; and (ii) nicking by decoating at either the micropylar or chalazal ends plus A niger. Micropylar scarification plus A niger gave the highest AGP (94%) followed by chalazal scarification plus A niger (86%) and hot water dip at 80°C + A niger (82%). The control seeds which were soaked in presterilised (by autoclaving at 121°C for 15 min) A niger spore suspension at 30°C gave zero germination.     

紫外诱变柠檬酸生产菌黑曲霉的选育

初步研究了柠檬酸生产菌黑曲霉产柠檬酸的影响因素和培养条件,通过紫外诱变考察了出发菌株的受诱变性,统计了紫外诱变黑曲霉引起的生物学效应,在紫外诱变过程中筛选到一株稳定高产菌株10min-3,产酸增加了5.33%,可作为进一步诱变筛选的出发菌株.     

Effect of Ozone on Aspergillus niger Causing Black Rot Disease in Onion

The effect of ozone on Aspergillus niger causing black rot disease in onion was studied in culture. Ozone induced the spore germination in all treatments and few spores showed rapid swelling, resulting in the production of 2-3 germ tubes per spore compared to control. Although all the ozone treated spores germinated, all of them did not produce uniform colony morphology. Some colonies which developed from ozone treated spores failed to produce spores and such colonies appeared as grey patches of mycelia without spores amidst surrounding black sporulating colonies. Further work is in progress to study the mechanism involved in formation of sterile mycelia by ozone.     

黑曲霉对含铅废水的生物吸附研究

研究黑曲霉真菌对污染废水中Pb^2＋的吸附．研究铅离子质量浓度、pH值、温度、灭菌与不灭菌以及重金属离子存在时对铅去除率的影响．结果表明：在实验条件下,Pb^2＋的最佳吸附质量分数是120mg／L,最适宜pH值为6．0,最佳温度为25℃．在20min取样时不灭菌对模拟废水中Pb^2＋的去除没有影响;20h时取样则由于环境中微生物与黑曲霉的竞争与协同作用使不灭菌的情况对铅的吸附明显好于灭菌的情况;干扰离子Hg^2＋、Cu^2＋、Zn^2＋的存在对铅的吸附无显著影响,并且在同一质量浓度情况下,这3种干扰离子的去除率大小为Zn^2＋〉Cu^2＋〉Hg^2＋．     

Biotechnological potential of industrial wastes for economical citric acid bioproduction by Aspergillus niger through submerged fermentation

Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL‐567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25–35 °C), pH (3–5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34 g L^?1 CA was recorded using BSL at pH 3.5 and temperature 30 °C after 120‐h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34 g L^?1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30 g L^?1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation.     

黑曲霉孢子灭活前后红外消光特性

黑曲霉孢子是生物气溶胶的重要组成部分,质量消光系数是研究黑曲霉孢子电磁衰减特性的重要参数。采用压片法测量了灭活前后黑曲霉孢子2.5~15 um 波段的反射光谱,并利用Krames-Kronig(K-K)关系计算了黑曲霉孢子红外波段的复折射率。基于Mie 散射理论求出了灭活前后黑曲霉孢子红外波段的质量消光系数,并对结果进行了分析和讨论。分析结果表明:3~5 um 波段,灭活后平均质量消光系数降低了4.6%,8~14 um 波段,灭活后平均质量消光系数降低了89.5%,由此可知,保持活性对于提高黑曲霉孢子的电磁衰减能力具有重要的意义。