荔枝剪枝堆肥和蚯蚓粪作为巨大普里斯特氏菌载体的研究

Use of lychee pruning compost and vermicompost as carriers of Priestia megaterium

为探讨荔枝茎秆堆肥与蚯蚓粪替代草炭作为巨大普里斯特氏菌载体的可行性,以荔枝剪枝堆肥、蚯蚓粪和草炭为原料构建6种微生物载体(ST1、ST2、ST3、ST4、ST5、ST6,三者质量比分别为6∶2∶2、4∶2∶4、2∶2∶6、6∶3∶1、4∶3∶3、2∶3∶5),以草炭为对照,巨大普里斯特氏菌为目标微生物,动态监测载体中有效活菌数,获得适宜巨大普里斯特氏菌存活的载体;在此基础上,分别设置含水量20%、30%、40%,温度20、30、40、50℃和接种浓度10^(6)、10^(7)、10^(8)cfu·mL^(-1),动态监测载体中有效活菌数,优化载体含水量、温度和接种浓度。结果表明:随着培养时间的延长,各载体中活菌数均呈先降低后升高的趋势,其中ST2、ST5载体长期培养后活菌数高,且草炭添加量低,是适宜的巨大普里斯特氏菌载体。随着载体含水量、温度的升高,培养的60 d过程中ST2和ST5载体活菌数均呈先升高后降低的趋势,在30%含水量(ST22.46×10^(8)cfu·g^(-1)、ST51.81×10^(8)cfu·g^(-1))以及30℃(ST23.44×10^(8)cfu·g^(-1)、ST51.87×10^(8)cfu·g^(-1))、40℃(ST28.50×10^(7)cfu·g^(-1)、ST57.13×10^(7)cfu·g^(-1))温度下的活菌数最高。此外,各培养时期的载体活菌数均随着接种浓度的升高而升高,培养60 d后,ST2、ST5载体活菌数分别达3.63×10^(8)、3.33×10^(8)cfu·g^(-1)。研究表明,载体ST2和ST5适宜代替草炭作为巨大普里斯特氏菌的载体,且在30%载体含水量、30~40℃温度和10^(8)cfu·mL^(-1)接种浓度下效果最佳。

This study aimed to evaluate the feasibility of lychee pruning compost and vermicompost to replace peat as carriers of Priestia megaterium.In the present experiment,we produced six mixed carriers of the target bacteria,P.megaterium,by using different ratios of lychee pruning compost,vermicompost,and peat;we labelled these different mixes as ST1,ST2,ST3,ST4,ST5,and ST6 with mass ratios of 6∶2∶2,4∶2∶4,2∶2∶6,6∶3∶1,4∶3∶3,and 2∶3∶5,respectively.The peat(CK)alone was used as the control.We dynamically monitored the viable counts within the carriers at different cultivation times to determine which mixed carrier formula was suitable for the survival of P.megaterium.On this basis,we set different water contents(20%,30%,40%),temperatures(20,30,40,50℃),and inoculation concentrations(10^(6),10^(7),10^(8) cfu·mL^(-1)),and dynamically monitored the living bacteria;we then optimized the water content,temperature,and inoculation concentration of the carriers accordingly.The results showed that the viable count of each carrier initially decreased then increased with the cultivation time.ST2 and ST5 were determined to both be optimal carriers of P.megaterium,according to their high viable counts of P.megaterium after long term of cultivation and their relatively low peat composition.After 60 days of cultivation,with increasing water content and temperature,viable counts increased before decreasing;the highest viability counts were achieved at 30% water content(ST22.46×10^(8) cfu·g^(-1),ST51.81×10^(8) cfu·g^(-1))and at 30℃(ST23.44×10^(8) cfu·g^(-1),ST51.87×10^(8) cfu·g^(-1))and 40℃(ST28.50×10^(7) cfu·g^(-1),ST57.13×10^(7) cfu·g^(-1)).Moreover,the viable count within the carrier at each cultivation stage increased with increasing inoculation concentrations;the viable counts of ST2 and ST5 reached 3.63×10^(8) and 3.33×10^(8) cfu·g^(-1),respectively,after 60 days of cultivation.Overall,the mixed carriers ST2 and ST5 are most suitable alternatives that can be used to replace peat as carriers of P.megaterium;the optimal conditions for these carriers are 30% water content,30-40℃ temperature,and 10^(8) cfu·mL^(-1) inoculation concentration.