Study On Inhibition Effect Of K-series, The Novel Anti-bacterial Agents, On Biological Contaminants

Biological contaminants are microbial organisms including bacteria, fungi, viruses and parasites which can lead to a bad effect on ecosystem。It is characterized by difficulty to predict,long period of latency and serious destruction。Remove of biological contaminants has become a hot field of environment pollution study. The target of this research is Ralstonia solanacearum which causes tobacco bacterial wilt that can decrease yield of tobacco and damage the quality . Therefore, it is an important issue we have to face during the production process to reduce and control bacterial wilt through studying Ralstonia solanacearum and finding effective prevention technologies and methods of bacterial wilt, especially looking for special effective bacteriostat. In recent years, there are many reports about screening and application of tobacco bacteriostat , however, they are still could not be applied in tobacco production because of their shortcomings . In order to look for the ideal bacteriostat , explore the effective technology of control and evaluate their environment safety ,several bacteriostats were screened in this paper, especially the K-serie(sK1,K2,K3),and their indoor and field inhibition effects and environmental impact were also evaluated。The main contents of the paper are as follows:1 Screening of bacteriostats against tobacco bacterial wilt (Ralstonia solanacearum)The inhibition effect of K1,K2,K3,agricultural streptomycin,CuSO₄,TiO₂-nanoparticles and potassium humate on Ralstonia solancearum were determined by the enumeration technique called suspension-dilution and plate-count method. The results indicated that: K1,K2,K3,Agricultural streptomycin,CuSO₄ could obviously inhibit Ralstonia solancearum, while TiO₂-nanoparticles and potassium humate did not have obvious effect and their inhibition effect are in the sequence of K3>K2>K1> Agricultural streptomycin >CuSO₄.Therefore, K1,K2,K3 were screened as bacteriostats against R. solanacearum, these K series may also have the potential to be used to control tobacco bacterial wilt in field.2 The indoor inhibition effect of K-series on biological contaminants:2.1 Study on Inhibition of K3 to Tobacco Bacterial Wilt (Ralstonia solanacearum) Ralstonia solanacearum were treated with glycosaminoglycan like compounds K3, a novel anti-bacterial agent, which had been screened by our laboratory. In order to explore the effect of K3 on R.solanacearum,inhibitory ratio and indoor toxicity test were determined. The results showed that1) R.solanacearum were all killed when the concentration of K3 was 10 mg/L or more. 99.52 % R.solanacearum were inhibited when the concentration of K3 reduced to 5mg/L. Even when treated with 0.2mg/L K3, the inhibitory ratio was still as high as 44.74%; 2) EC₅,EC₅₀,EC₉₅ of K3 to R.solanacearum were 0.017,0.229,3.064mg/L respectively. These results demonstrated that K3 had a strong inhibiting effect on R.solanacearum.2.2 Study on inhibition effect of k-series, the novel anti-bacterial agent, on nationwide tobacco Ralstonia solancearumThe inhibition effect of a novel anti-bacterial agent K-series(K1,K2,K3) on nationwide strains of tobacco Ralstonia solancearum was assessed by suspension-dilution and plate-count method. Different inhibitory strength between K series and Agricultural streptomycin were compared. The results indicated that: 1)100% inhibition of K1(100mg/L) on strains of tobacco Ralstonia solancearum were as follows: Yinjiang,Dejiang,Shiqian,Suiyang,Tongzi,Qianxi,Jinsha,Bijie(county-level city),Fuquan,Zhongke,Huishui,Pingtang,Dushan,Majiang,Sansui,Xianfeng,Miyi,Laoshan,Zhucheng,Qianjiang,Jinsha,Longyang,Yongzhou,Shitai,Tobacco Research Institute of Anhui ; 100% inhibition of K2(100mg/L) on strains were as follows: Yinjiang,Jiangkou,Dejiang,Sinan,Shiqian two,Suiyang,Tongzi,Zunyi xian,Daozhen,Renhuai,Bijie city,Wengan,Huishui,Pingtang,Dushan,Qiandongnan,Xuanen,Dechang,Shandong province,Qianjiang,Changning,Longyang,Qiubei,Sanming,Nanxiong,Yongzhou,Shitai,Tobacco Research Institute of Anhui; 100% inhibition of K3(50mg/L) on strains were as follows:Muhuang,Dejiang,Suiyang,Tongzi,Zunyi xian,Qianxi,Dafang,Bijie(county-level city),Lishan xiang,Pingtang,Dushan,Tianzhu,Sansui,Dechang,Juxian,Zhucheng,Qianjiang,Changning,Longyang,Qiubei,Sanming,Nanxiong,Yongzhou,Shitai,Tobacco Research Institute of Anhu; 100% inhibition of Agricultural streptomycin (254.5mg/L) on strains were as follows: Tongren,Suiyang,Zunyi xian,Daozhen,Renhuai,Qianxi,Dafang,Bijie(county-level city),Lishan xiang,Yuhuaxiang,Pingtang,Dushan,Tianzhu,Sansui,Xianfeng,Xuanen,Miyi,Dechang,Juxian,Zhucheng,Qianjiang,Baoshan city,Qiubei,Sanming,Nanxiong,Yongzhou,Shitai,Tobacco Research Institute of Anhu;2) When compared with same concentration(50mg/L) of Agricultural streptomycin, K-series had a higher inhibition on several strains. To K1, these strains come from Yangxi xiang,Jiangkou, Shiqian,Suiyang,Tongzi,Daozhen,Jinsha,Fuquan,Zhongke zhen,Huishui,Majiang,Miyi,Laoshan,Yongzhou,Shitai; To K2, these strains come from Yangxi xiang,Jiangkou,Sinan,Tongzi,Zunyi xian,Daozhen,Renhuai,Jinsha,Longchang zhen,Wengan,Huishui,Majiang,Tianzhu,Xuanen,Laoshan,Juxian,Longyang,Yongping,Qiubei,Yongzhou,Shitai; To K3, these strains come from Jiangkou,Sinan,Shiqian,Zunyi city,Dafang,Jinsha,Fuquan,Wengan,Huishui,Majiang,Tianzhu,Xuanen,Juxian,Shidian,Longyang,Qiubei,Yongzhou,Shitai. It was obvious that stains form different districts had different sensitivities when they responsed to K-series anti-bacterial agent. Therefore, using an appropriate bacteriostat with an rational concentration to control bacterial wilt of tobacco caused by Ralstonia solancearum in different places may be a feasible choice.2.3 Study on inhibition effect of glycosaminoglycan K1 and K2 on Phytophthora parasitica var.nicotianaeThe inhibition effect of K1 and K2 on Phytophthora parasitica var. nicotianae were determined by the growth rate method.The results indicated that:K1 and K2 could obviously inhibit Phytophthora parasitica var.nicotianae,the inhibition effects improved as the increasing of their concentrations.The inhibition rates of K1 and K2 at the concentrations of 20mL/L were 50.58% and 84.68% respectively;The EC50 of K1 and K2 were 26.15mL/L and 4.87mL/L respectively.Therefore,K1,K2 may be a potential control to tobacco black shank.3 Inhibition effect of K-series on biological contaminants in fieldMaking use of 100mg/L K2 with 6 different ways (adhere root,Irrigation root,adhere root+ spray on leaves,adhere root+ spray on leaves twice,adhere root+ spray on leaves triple,Irrigation root twice in rosette stage)on tobacco bacterial wilt nursery of Sanming city of Fujian province in 2010. In the same year, applying 100mg/L K2 in 5 different treatments( adhere root,Irrigation root,adhere root+ spray on leaves,adhere root+ spray on leaves twice,adhere root+ spray on leaves triple)to control Ralstonia solancearum under 2 field experiments in Yongzhou city of Hunan province(Ruyong village of Jiangyong county ,ZhouGuBa village of Ningyuan county).The results indicated that every treatment has an obvious inhibition effect on Ralstonia solancearum in 4 sites of two province. One of the treatments( adhere root+ Spray on leaves twice) has a better effect in all, whose control effect is up to 72%.4 Study on ecological affect of glycosaminoglycan(K2) to soil environment Effects of different concentrations of K2(5,50,500mg/kg), a novel anti-bacterial agent, on eco-systerm of soil were investigated in a 63-day laboratory culture experiment by studying soil microbial population, respiration rates and dehydrogenase activity. The result showed that : effects of K2 on the population of bacteria and actinomycete are similar to each other for there were inhibition-simulation-inhibition trend; The population of bacteria and actinomycete in soil recovered to normal level after 49,56 days respectively. K2 had a simulation effect on the population of fungi, their effects disappeared 49 days later。K2 had a little inhibition effect on respiration rates at former two weeks, then simulated respiration significantly, finally had no effects in 56 days later.The effect-mode of K2 on dehydrogenase activity was simulation-inhibition-simulation and had no significant differences compared with the control(without K2) after 56 days. Therefore, this anti-bacterial agent K2 has different phase effects on soil eco-systerm during the whole experiment and it is also reversible.