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首页> 美国卫生研究院文献>World Journal of Biological Chemistry >Effect of agitation speed on the morphology of Aspergillus niger HFD5A-1 hyphae and its pectinase production in submerged fermentation
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Effect of agitation speed on the morphology of Aspergillus niger HFD5A-1 hyphae and its pectinase production in submerged fermentation

机译：搅拌速度对深层发酵中黑曲霉HFD5A-1菌丝形态及其果胶酶产生的影响

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AIM: To investigate the impact of agitation speed on pectinase production and morphological changing of Aspergillus niger (A. niger) HFD5A-1 in submerged fermentation.METHODS: A. niger HFM5A-1 was isolated from a rotted pomelo. The inoculum preparation was performed by adding 5.0 mL of sterile distilled water containing 0.1% Tween 80 to a sporulated culture. Cultivation was carried out with inoculated 1 × 107 spores/mL suspension and incubated at 30 °C with different agitation speed for 6 d. The samples were withdrawn after 6 d cultivation time and were assayed for pectinase activity and fungal growth determination. The culture broth was filtered through filter paper (Whatman No. 1, London) to separate the fungal mycelium. The cell-free culture filtrate containing the crude enzyme was then assayed for pectinase activity. The biomass was dried at 80 °C until constant weight. The fungal cell dry weight was then expressed as g/L. The 6 d old fungal mycelia were harvested from various agitation speed, 0, 50, 100, 150, 200 and 250 rpm. The morphological changing of samples was then viewed under the light microscope and scanning electron microscope.RESULTS: In the present study, agitation speed was found to influence pectinase production in a batch cultivation system. However, higher agitation speeds than the optimal speed (150 rpm) reduced pectinase production which due to shear forces and also collision among the suspended fungal cells in the cultivation medium. Enzyme activity increased with the increasing of agitation speed up to 150 rpm, where it achieved its maximal pectinase activity of 1.559 U/mL. There were significant different (Duncan, P < 0.05) of the pectinase production with the agitation speed at static, 50, 100, 200 and 250 rpm. At the static condition, a well growth mycelial mat was observed on the surface of the cultivation medium and sporulation occurred all over the fungal mycelial mat. However with the increased in agitation speed, the mycelial mat turned slowly to become a single circular pellet. Thus, it was found that agitation speed affected the morphological characteristics of the fungal hyphae/mycelia of A. niger HFD5A-1 by altering their external as well as internal cell structures.CONCLUSION: Exposure to higher shear stress with an increasing agitation speed could result in lower biomass yields as well as pectinase production by A. niger HFD5A-1.
机译：目的：研究搅拌速度对黑曲霉HFD5A-1在深层发酵中果胶酶产生和形态变化的影响。方法：从腐烂的柚子中分离出黑曲霉HFM5A-1。接种物的制备是通过向孢子培养物中加入5.0 mL含0.1％Tween 80的无菌蒸馏水来进行的。用接种的1×10 7 孢子/ mL悬浮液进行培养，并在30°C下以不同的搅拌速度孵育6 d。培养6天后取出样品，并测定果胶酶活性和真菌生长测定。将培养液通过滤纸（Whatman No. 1，London）过滤以分离真菌菌丝体。然后测定含有粗酶的无细胞培养物滤液的果胶酶活性。将生物质在80°C干燥至恒重。然后将真菌细胞干重表示为g / L。从0、50、100、150、200和250 rpm的各种搅拌速度收获6d老真菌菌丝体。结果：在本研究中，发现搅拌速度会影响分批培养系统中果胶酶的生产。但是，高于最佳速度（150 rpm）的搅拌速度会降低果胶酶的产生，这是由于剪切力以及培养基中悬浮的真菌细胞之间的碰撞所致。酶的活性随着搅拌速度的增加而增加，最高到150 rpm，达到最大的果胶酶活性1.559 U / mL。在静态，50、100、200和250 rpm的搅拌速度下，果胶酶的产量有显着差异（Duncan，P <0.05）。在静态条件下，在培养基表面观察到了生长良好的菌丝体垫，并且在整个真菌菌丝体垫上都发生了孢子形成。然而，随着搅拌速度的增加，菌丝体垫缓慢旋转成单个圆形颗粒。因此，发现搅拌速度会通过改变其外部和内部细胞结构来影响黑曲霉HFD5A-1的真菌菌丝/菌丝的形态特征。结论：随着搅拌速度的增加，暴露于较高的剪切应力下可能会导致黑曲霉HFD5A-1降低了生物量的产量以及果胶酶的产量。

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