As a new agro-antibiotic, Streptomyces Lavendulae has gained its permit control more than ten diseases, such as Rice bacterial blight, Apple perennial canker, Chinese cabbage soft rot, Cucumber bacterial angular leaf spot, Bean bacterial blight, Asparagus stem blight, Pepper bacterial spot, Ginger blast, Citrus canker, Tomato bacterial wilt, etc. Its production and application was listed as one of the key programs of national agro-technical extension. Streptomyces Lavendulae producing strain is a streptomyces, which was numbered B-7.It was separated from soil by the institute of Medical and Pharmaceutical biotechnology, China.
1. The toxicity of Streptomyces Lavendulae to animals and its residual dose determination in plants and soils.
1.1 Toxicity assessment of Streptomyces Lavendulae to animals
（l）Acute toxicity ：white mouse oral toxicity test : medium lethal dose (LD50) of the industrial sample amounts to 10000mg/kg; LD50 of the pure sample is 316mg/kg for males, and 237mg/kg for females. White mouse percutaneous toxicity test: LD50 of the industrial sample＞l0000mg／kg；
（2）No irritation to skin and eyes：skin test of the white rabbit showed that no erythema and edema formed. 1-24h after treatment of eyes, there were slight hyperaemia and edema in conjunctiva, no secretion. The cornea was normal. Restored after 48h；
（3）Cumulative Toxicity : The cumulative coefficient is 5.8. It was calculated as follows: When half dead, the gross absorption volume of the sample divides LD50 ;
（4）Teratogenic test ：Filled the big mouse’s stomach for 10 consecutive days( from the 6th day to 15th day) of its pregnancy with the dose of 0.766-15.32mg/kg. For each dose, filled 0.5mg /100g (weight) each time. No negative influence on the embryo. According to X2 examination, no significant differences were observed between treatments and the control due to the dead embryo, bone teratogenity and viscera.
（5）Micronucleus test：no damage to chromosome; no teratogenicity to germ cells ;
（6）Mutagenicity test: No mutagenicity. With the method of Ames standard plate，results showed no significant difference existed between treatments and the control.
1.2 Determination of the residues in plant and soil
（l）Sample preparation
Choose the field with well-grown lotus cabbage and set the control and treatment areas. After spraying Streptomyces Lavendulae, took the sample of the control soil, control cabbage, treated soil and treated cabbage for 10 consecutive days. The cabbage sample was crashed in the tissue crasher and soaked with water for 24h, then the cabbage residues were filtered out with gauze. After that, the filtrate was filtered with filter paper for two times and vacuum flirtation was conducted with Brandt funnel. Finally, the filtrate was evaporated at the bath of 50℃to smaller volume and freezed dry.
The soil sample was scattered with water, soaked for 24h, filtered with gauze and then filtered again with filter paper and Brandt funnel. Finally, the filtrate was concentrated and freezed-dry.
（2）Sample determination
Since Streptomyces Lavendulae belonged to N-glycoside antibiotics and its UV spectrum was of end absorption, it could not be detected under the general UV spectrum scope. It could only be detected by the following method. Mix the sample with Ophthalaldehyde and conduct derivatization reaction under a certain condition. Then we get the fluorescent product and separate it using reversed phase chromatography, detected by fluorescence detector. This method is super sensitive and the minimum detection dose is 6.9×10-2 pps with good repeatability. The relative standard deviation(CV) was 0.2372％.The recovery ratio was 97.09％。
（3）Detection result
The detected content was 0.185μg/ml on the first day after spraying Streptomyces Lavendulae. On the 7th day was 0.001μg/ml，and none on the 8th day. The results indicated that the residue dose of Streptomyces Lavendulae was extremely low and it could only last 7days, so it caused no pollution to the environment and no toxicity to human beings and livestock.
2. Application of Streptomyces Lavendulae
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Control object
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Application period and method
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Application concentration and method
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Apple perennial canker, Gloeosporium rot,Mouldy core, and Spot stain, Peach bacterial shot hole
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spray for the first time at the phase of flourishing florescence，then one time every 15-20d.Spray with Bordeaux liquid(mixture of CuSO4,CaO and water) by turns at the late phage,4-5 times for Zhongshengmycin in total.
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30－40μg/ml, spray
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Chinese cabbage soft rot
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Dressing and spray two times from the phase of seedling to lotus.
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60μg/ml, Dress 30－40μg/ml, spray
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Solanacae crops bacterial wilt
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Irrigate roots at the beginning of the disease for successive 2-3 times.
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30－40μg/ml irrigate roots
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Cucumber bacterial angular leaf spot , Bean bacterial blight, Asparagus stem blight, Pepper bacterial Spot
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Spray at the beginning of the disease.
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30－40μg/ml, spray
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Rice bacterial blight
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Soak with Warm water（55℃,then let the temperature drop naturally）for 36-48h , spray at the phase of seedling with 5 leaves and the 5th day before transfer respectively; spray in the field if the disease broke out.
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80μg/ml, soak seeds
30－40μg/ml , spray
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Citrus canker
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Spray one time every 10 days since the bud phase, 6-8times for all.
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30－40μg/ml, spray
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Ginger blast
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Soak seeds and irrigate the root at the beginning of the disease
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30－40μg/ml, irrigate roots
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Products under patent are for R&D purpose only. |
