PDF(Pubmed)
Abstract：
BACKGROUND: Bacterial genomes often encode structures similar to phage capsids (encapsulins) and phage tails which can be induced spontaneously or using genotoxic compounds such as mitomycin C. These high molecular-weight (HMW) putative antibacterial proteins (ABPs) are used against the competitive strains under natural environment. Previously, it was unknown whether these HMW putative ABPs originating from the insect pathogenic Gram-positive, spore-forming bacterium Brevibacillus laterosporus (Bl) isolates (1821L, 1951) are spontaneously induced during the growth and pose a detrimental effect on their own survival. Furthermore, no prior work has been undertaken to determine their biochemical characteristics.
RESULTS: Using a soft agar overlay method with polyethylene glycol precipitation, a narrow spectrum of bioactivity was found from the precipitated lysate of Bl 1951. Electron micrographs of mitomycin C- induced filtrates showed structures similar to phage capsids and contractile tails. Bioactivity assays of cell free supernatants (CFS) extracted during the growth of Bl 1821L and Bl 1951 suggested spontaneous induction of these HMW putative ABPs with an autocidal activity. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of spontaneously induced putative ABPs showed appearance of ~ 30 kDa and ~ 48 kDa bands of varying intensity across all the time intervals during the bacterial growth except in the initial hours. Statistically, spontaneously induced HMW putative ABPs of Bl 1951 exhibited a significant decrease in the number of viable cells of its producer strain after 18 h of growth in liquid. In addition, a significant change in pH and prominent bioactivity of the CFS of this particular time period was noted. Biochemically, the filtered supernatant derived from either Bl 1821L or Bl 1951 maintained bioactivity over a wide range of pH and temperature.
CONCLUSIONS: This study reports the spontaneous induction of HMW putative ABPs (bacteriocins) of Bl 1821L and Bl 1951 isolates during the course of growth with potential autocidal activity which is critically important during production as a potential biopesticide. A narrow spectrum of putative antibacterial activity of Bl 1951 precipitate was found. The stability of HMW putative ABPs of Bl 1821L and Bl 1951 over a wide range of pH and temperature can be useful in expanding the potential of this useful bacterium beyond the insecticidal value.
RESULTS: Using a soft agar overlay method with polyethylene glycol precipitation, a narrow spectrum of bioactivity was found from the precipitated lysate of Bl 1951. Electron micrographs of mitomycin C- induced filtrates showed structures similar to phage capsids and contractile tails. Bioactivity assays of cell free supernatants (CFS) extracted during the growth of Bl 1821L and Bl 1951 suggested spontaneous induction of these HMW putative ABPs with an autocidal activity. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of spontaneously induced putative ABPs showed appearance of ~ 30 kDa and ~ 48 kDa bands of varying intensity across all the time intervals during the bacterial growth except in the initial hours. Statistically, spontaneously induced HMW putative ABPs of Bl 1951 exhibited a significant decrease in the number of viable cells of its producer strain after 18 h of growth in liquid. In addition, a significant change in pH and prominent bioactivity of the CFS of this particular time period was noted. Biochemically, the filtered supernatant derived from either Bl 1821L or Bl 1951 maintained bioactivity over a wide range of pH and temperature.
CONCLUSIONS: This study reports the spontaneous induction of HMW putative ABPs (bacteriocins) of Bl 1821L and Bl 1951 isolates during the course of growth with potential autocidal activity which is critically important during production as a potential biopesticide. A narrow spectrum of putative antibacterial activity of Bl 1951 precipitate was found. The stability of HMW putative ABPs of Bl 1821L and Bl 1951 over a wide range of pH and temperature can be useful in expanding the potential of this useful bacterium beyond the insecticidal value.
摘要：
背景:细菌基因组通常编码类似于噬菌体衣壳(封装蛋白)和噬菌体尾的结构,其可以自发诱导或使用基因毒性化合物如丝裂霉素C。这些高分子量(HMW)推定的抗细菌蛋白(ABP)在自然环境下用于对抗竞争性菌株。以前,尚不清楚这些HMW推定的ABP是否源自昆虫致病性革兰氏阳性，孢子形成细菌侧孢短芽孢杆菌（Bl）分离株（1821L，1951）是在生长过程中自发诱导的，对它们自己的生存产生不利影响。此外，以前没有进行任何工作来确定它们的生化特性。
结果：使用聚乙二醇沉淀的软琼脂覆盖法，从Bl1951的沉淀裂解物中发现了窄谱的生物活性。丝裂霉素C诱导的滤液的电子显微照片显示类似于噬菌体衣壳和收缩尾的结构。在Bl1821L和Bl1951生长期间提取的无细胞上清液(CFS)的生物活性测定表明这些具有自杀活性的HMW推定的ABP的自发诱导。自发诱导的推定ABP的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示，在细菌生长过程中的所有时间间隔中，除了最初的几个小时外，都出现了〜30kDa和〜48kDa的强度不同的条带。统计上,自发诱导的HMW推定的Bl1951ABP在液体中生长18小时后，其生产菌株的活细胞数量显着减少。此外,注意到这一特定时间段的CFS的pH值和显着的生物活性发生了显着变化。生物化学,例如,来源于Bl1821L或Bl1951的过滤的上清液在宽范围的pH和温度下保持生物活性。
结论:本研究报告了在生长过程中Bl1821L和Bl1951分离株的HMW推定的ABP(细菌素)的自发诱导,其具有潜在的自杀活性,这在作为潜在的生物农药的生产过程中是至关重要的。发现了Bl1951沉淀物的推定抗菌活性的窄谱。Bl1821L和Bl1951的HMW推定ABPs在宽范围的pH和温度下的稳定性可用于将这种有用细菌的潜力扩大到超出杀虫值。
结果：使用聚乙二醇沉淀的软琼脂覆盖法，从Bl1951的沉淀裂解物中发现了窄谱的生物活性。丝裂霉素C诱导的滤液的电子显微照片显示类似于噬菌体衣壳和收缩尾的结构。在Bl1821L和Bl1951生长期间提取的无细胞上清液(CFS)的生物活性测定表明这些具有自杀活性的HMW推定的ABP的自发诱导。自发诱导的推定ABP的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示，在细菌生长过程中的所有时间间隔中，除了最初的几个小时外，都出现了〜30kDa和〜48kDa的强度不同的条带。统计上,自发诱导的HMW推定的Bl1951ABP在液体中生长18小时后，其生产菌株的活细胞数量显着减少。此外,注意到这一特定时间段的CFS的pH值和显着的生物活性发生了显着变化。生物化学,例如,来源于Bl1821L或Bl1951的过滤的上清液在宽范围的pH和温度下保持生物活性。
结论:本研究报告了在生长过程中Bl1821L和Bl1951分离株的HMW推定的ABP(细菌素)的自发诱导,其具有潜在的自杀活性,这在作为潜在的生物农药的生产过程中是至关重要的。发现了Bl1951沉淀物的推定抗菌活性的窄谱。Bl1821L和Bl1951的HMW推定ABPs在宽范围的pH和温度下的稳定性可用于将这种有用细菌的潜力扩大到超出杀虫值。
