淡水硅藻的大量培养

淡水硅藻是水生动物的营养丰富的食料。经过一年的筛选培养,我们获得了四种适于大量培养的种类,即:泉生偏缝硅藻（Nitzschia fonticola Grun.）,椿状偏缝硅藻（Nitzschia palea Smith.）,双尖菱板硅藻（Hantzschia amphioxys Grun.）和梅尼小环硅藻（Cyclotella meneghini-ana Kütz.）。我们选择泉生偏缝硅藻进行较为系统的培养试验,对其营养成分进行了分析,并对其所含的15种氨基酸进行了定量。同时配制了两个新的适于硅藻生长繁殖的培养基“水生硅1”和“水生硅2”。泉生偏缝硅藻最适生长温度为20—30℃,光强为2,000—5,000米烛光。观察了泉生偏缝硅藻在中型培养和大量培养中氮、磷、硅的吸收消耗规律,发现在培养条件下,硅是主要限制因子。在中型培养中,连续培养15天,适时补充营养元素,硅藻细胞数可高达23×106个/毫升,产量为2.7克干藻/升。在30升大量培养中获得每两天收获一次,每次收获1/6（相当于硅藻干重7克）的连续生产性培养的结果。根据实验结果推算,若两天半收获一次,每次收获1/6,可获得持续稳定高产。  

MASS CULTURE OF FRESHWATER DIATOMS

Being rich in nutrition,freshwater diatoms are favored food of many aquaticanimals.In 1973,experiments were started to investigate the possibilities of culturingdiatoms as a source of food for the larvae of crabs,shellfish and other aquatic ani-mals.Through screening and cultivation for about a year,we have sorted out 4species of freshwater diatoms suitable for mass culture from the environs of Wuhan,namely,Nitzschia fonticola,N.palea,Hantzschia amphioxys,and Cyclotella meneghi-niana.N.fonticola has been chosen for a series of cultivation experiments.The lipidand protein contents,as well as 15 amino acids,are determined quantitatively.Wehave also prepared two new culture media,“HB-D 1”and“HB-D 2”,which provesatisfactory for the propagation of diatoms.The optimum temperature for the growth of N.fonticola is 20—30℃,optimumlight intensity,2,000—5,000 lux.We have observed the regularity of the absorptionand consumption of nitrogen,phosphorus and silicon by N.fonticola in both themiddle-scale experiment and the mass culture.Under our culturing conditions,itseems that silicon is the principal limiting factor.In the middle-scale experiments,whenthe nutritional elements were supplied in time throughout a period of 15 days,the cellcount increased up to 23×106/ml,O.D.420nm=40,corresponding to a yield of2.76 grams dry weight per litre.In the 30-litre mass culture experiment,harvestedone-sixth the total amount of the culture every 2 days,a yield corresponding to 7grams dry weight each time has been obtained consecutively.The culture removedwas replaced by fresh medium.Judging from our experimental results,we presumethat a steady high yield could be obtained should the culture be harvested every2.5 days at the rate of 1/6 each time.