微生物对麦汁过滤性能和大麦呼吸活性的影响

Effects of microorganisms on filtration performance of wort and respiratory activityof barley

通过研究国产江苏啤酒大麦在制麦过程中微生物和发芽谷物间互作关系,确定因微生物导致的国产大麦麦芽质量缺陷原因。对麦汁混浊物分析表明,多糖类物质是其主要成分。利用PCR-DGGE方法鉴定出的10种不同细菌群,序列分析显示大多数为革兰氏阴性菌,主要是假单胞菌属。通过抑制假单胞菌的数量,麦汁浊度和过滤时间指标均有显著提升。在制麦过程中分离并鉴定了4株假单胞菌,分别为荧光假单胞菌(P.fluorescens)、恶臭假单胞菌(P.putida)、产黄假单胞菌(P.synxantha)和铜绿假单胞菌(P.aeruginosa)。这些菌株都有形成生物膜和产胞外多糖能力。接种假单胞菌大麦呼吸活性最差,发芽和溶解性能均不及对照大麦。研究结果表明制麦过程中假单胞菌形成生物膜并分泌胞外多糖影响麦汁过滤性能,同时与大麦争夺浸麦水中的溶解氧影响大麦呼吸活性。

The main goal of this thesis was to study the relationship between microbes and the germinating grain during the malting process of Jiangsu malting barley,to find out the reasons for the quality defects of domestic barley malt caused by microorganisms.The analysis of turbidity in wort showed that polysaccharide was the main component.Sequence analysis of 10 different bacterial communities identified by PCR-DGGE showed that most of them were Gram-negative bacteria,mainly pseudomonas.The turbidity and filtration time of wort were significantly increased by inhibiting the number of pseudomonas.Four pseudomonas were isolated and identified during malting,including P.fluorescens,P.putida,P.synxantha and P.aeruginosa.These strains all had the ability to form biofilm and produce extracellular polysaccharide.Barley inoculated with Pseudomonas had the worst respiratory activity and the germination and solubility of barley were inferior to control barley.The results showed that Pseudomonas formed biofilm and secreted extracellular polysaccharide during malting,which affected the filtration performance of wort,and competing with barley for dissolved oxygen in steeping affected the malt respiration activity.