植物乳杆菌LAB2对辣椒软腐病的控制作用及辣椒贮藏品质的影响

Soft rot controlling of pepper by Lactobacillus plantarum LAB2 and its effect on storage quality of pepper

细菌性软腐病是辣椒采后主要病害之一,该研究旨在探究拮抗乳酸菌控制辣椒软腐病的应用潜力。胡萝卜软腐病果胶杆菌CBJ3(Pcc CBJ3)致病性分析表明25℃(≥3 lg CFU/mL)和4℃(8 lg CFU/mL)贮藏下,均可致辣椒软腐率达100%,致腐性极强。从辣椒上筛选出一株对Pcc CBJ3有强抑菌活性的拮抗菌LAB2,经16S rDNA鉴定为植物乳杆菌(Lactobacillus plantarum)。L.plantarum LAB2所产细菌素以及无细胞发酵液(cell-free fermentation supernatant,CFS)对Pcc CBJ3均有体外抑菌活性。通过基因组草图序列在数据库比对鉴定到了4个细菌素:plantaricin_E、plantaricin_F、plantaricin_N和plantaricin_J。体内控病试验表明L.plantarum LAB2所产细菌素和CFS对辣椒软腐病均有控制效果,且CFS控病能力更强,显著降低了软腐病发病率和病斑直径(P<0.05)。扫描电镜显示,CFS处理可维持辣椒表皮结构的完好性。微生物计数结果表明,CFS处理可显著降低辣椒上的病原菌数量(P<0.05)。进一步研究结果显示,CFS处理可显著延缓辣椒贮藏期的硬度下降、失水、可溶性固形物含量流失、丙二醛的积累(P<0.05)。该研究为辣椒采后贮藏保鲜生物防治技术应用提供参考。

Bacterial soft rot is one of the main diseases of postharvest pepper.This study aimed to explore the application potential of antagonistic lactic acid bacteria to control soft rot of postharvest pepper.Pathogenicity analysis of Pectobacterium carotovorum subsp.carotovorum CBJ3(Pcc CBJ3)showed that storage at 25℃(≥3 lg CFU/mL)and 4℃(8 lg CFU/mL)could cause pepper soft rot rate of 100%.It indicated that Pcc CBJ3 had strong pathogenicity.An antagonistic strain LAB2 with strong antibacterial activity against Pcc CBJ3 was screened from pepper and identified to be Lactobacillus plantarum by 16S rDNA.The bacteriocin and cell-free fermentation supernatant(CFS)of L.plantarum LAB2 had antibacterial activity against Pcc CBJ3 in vitro.Four bacteriocins,plantaricin_E,plantaricin_F,plantaricin_N,and plantaricin_J,were identified by database comparison using draft genome sequences.The result of disease control in vivo showed that bacteriocin and CFS of L.plantarum LAB2 both had disease control effect on pepper soft rot,and CFS performed better,which significantly reduced the disease incidence and the lesion diameter of soft rot(P<0.05).Scanning electron microscopy showed that CFS could maintain the integrity of pepper epidermis structure.Microbial counting result showed that CFS significantly reduced the number of pathogens in pepper(P<0.05).Further studies showed that CFS could delay the firmness decrease,water loss,soluble solid content loss,and malondialdehyde accumulation of pepper during storage.This study provides a reference for the application of biological control technology in storage and preservation of postharvest pepper.