Suarez Christian, Ratering Stefan, Weigel Victoria, Sacharow Julia, Bienhaus Jackeline, Ebert Janine, Hirz Anika, Rühl Martin, Schnell Sylvia
Institute of Applied Microbiology, IFZ, Justus-Liebig University Giessen, 35392, Giessen, Germany.
Institute of Applied Microbiology, IFZ, Justus-Liebig University Giessen, 35392, Giessen, Germany.
Microbiol Res. 2019 Dec 13;234:126393. doi: 10.1016/j.micres.2019.126393.
Pleurotus ostreatus is one of the most cultivated edible mushrooms worldwide and few approaches have been done to analyze bacterial influence during its cultivation. Therefore, bacteria from commercial spawn, mycelial-colonized straw and fruiting bodies from healthy productive samples were counted, isolated and tested for their mycelial growth promoting ability. Bacterial cell numbers at different steps of the process showed low bacterial cell numbers in spawn and in fruiting bodies inner tissue compared to the high concentration in mycelial-colonized straw. The majority of the 38 isolates belonged to phyla Firmicutes and Actinobacteria were identified as Bacillus, Paenibacillus and Micromonospora species. Similarly, 16S rRNA gene bacterial clones obtained from mycelial biomass DNA samples showed bacterial presence of various genera including Bacillus and Paenibacillus. In the mycelial growth promoting ability tests, 30 isolates negatively affected mycelial growth, two isolates showed no effect on mycelial growth, and six isolates promoted mycelial growth. Moreover, mycelial thickness was influenced in different ways by the bacterial growth. In general, nearly all isolates growth-preventing were isolated from healthy spawn and mycelial-colonized straw, whereas fruiting bodies were the best source for isolation of mycelial growth-promoting bacteria. Characterization of bacterial isolates revealed that growth-preventing isolates exhibited various enzymatic activities in comparison with positive influencing bacteria that exhibited none or weak enzymatic activities. In addition, the influence of volatile compounds being present in the headspace of bi-plate co-cultures on P. ostreatus mycelial growth was demonstrated. The effect of isolates, that promoted mycelial growth in co-cultivation, to reduce P. ostreatus spawn running time, was evaluated on sterilized rye seeds. Results showed that not all mycelial promoted isolates were able to significantly promote P. ostreatus colonization. However, isolate M46F identified as Micromonospora lupini significantly reduce spawn running time. This is one of few studies to estimate cultivable bacteria from healthy samples of P. ostreatus cultivation, to evaluate a bacterial effect on mycelial growth, to show that fruiting bodies are a good source for mycelia growth-promoting isolates, and the first to report a shorter P. ostreatus spawn running time due to bacterial inoculation.
糙皮侧耳是全球栽培最为广泛的食用蘑菇之一，然而，针对其栽培过程中细菌影响的分析方法却很少。因此，对来自商业菌种、菌丝定殖的秸秆以及健康高产样本的子实体中的细菌进行了计数、分离，并测试了它们促进菌丝生长的能力。与菌丝定殖秸秆中的高细菌浓度相比，该过程不同步骤中的细菌细胞数量显示，菌种和子实体内组织中的细菌细胞数量较低。38株分离菌中的大多数属于厚壁菌门和放线菌门，被鉴定为芽孢杆菌属、类芽孢杆菌属和小单孢菌属。同样，从菌丝生物质DNA样本中获得的16S rRNA基因细菌克隆显示存在包括芽孢杆菌属和类芽孢杆菌属在内的各种属细菌。在促进菌丝生长能力测试中，30株分离菌对菌丝生长有负面影响，2株分离菌对菌丝生长无影响，6株分离菌促进了菌丝生长。此外，细菌生长以不同方式影响菌丝厚度。一般来说，几乎所有抑制生长的分离菌都来自健康的菌种和菌丝定殖的秸秆，而子实体是分离促进菌丝生长细菌的最佳来源。细菌分离菌的特性表明，与没有或仅有微弱酶活性的正向影响细菌相比，抑制生长的分离菌表现出各种酶活性。此外，还证明了双平板共培养顶空中存在的挥发性化合物对糙皮侧耳菌丝生长的影响。在灭菌黑麦种子上评估了在共培养中促进菌丝生长的分离菌对缩短糙皮侧耳菌种萌发时间的效果。结果表明，并非所有促进菌丝生长的分离菌都能显著促进糙皮侧耳的定殖。然而，被鉴定为羽扇豆小单孢菌的分离菌M46F显著缩短了菌种萌发时间。这是为数不多的几项研究之一，旨在从糙皮侧耳栽培的健康样本中估计可培养细菌，评估细菌对菌丝生长的影响，表明子实体是促进菌丝生长分离菌的良好来源，并且首次报道了由于细菌接种而使糙皮侧耳菌种萌发时间缩短。
