Microbiological Features and Bioactivity of a Fermented Manure Product (Preparation 500) Used in Biodynamic Agriculture
Matteo Giannattasio, Elena Vendramin, Flavio Fornasier, Sara Alberghini, Marina Zanardo, Fabio Stellin, Giuseppe Concheri, Piergiorgio Stevanato, Andrea Ertani, Serenella Nardi, Valeria Rizzi, Pietro Piffanelli, Riccardo Spaccini, Pierluigi Mazzei, Alessandro Piccolo and Andrea Squartini
Abstract
The fermented manure derivative known as Preparation 500 is traditionally used as a field spray in biodynamic agriculture for maintaining and increasing soil fertility. This work aimed at characterizing the product from a microbiological standpoint and at assaying its bioactive properties. The approach involved molecular taxonomical characterization of the culturable microbial community; ARISA fingerprints of the total bacteria and fungal communities; chemical elemental macronutrient analysis via a combustion analyzer; activity assays for six key enzymes; bioassays for bacterial quorum sensing and chitolipooligosaccharide production; and plant hormonelike activity. The material was found to harbor a bacterial community of 2.38 × 108 CFU/g dw dominated by Grampositives with minor instances of Actinobacteria and Gammaproteobacteria. ARISA showed a coherence of bacterial assemblages in different preparation lots of the same year in spite of geographic origin. Enzymatic activities showed elevated values of β-glucosidase, alkaline phosphatase, chitinase, and esterase. The preparation had no quorum sensing-detectable signal, and no rhizobial nod gene-inducing properties, but displayed a strong auxin-like effect on plants. Enzymatic analyses indicated a bioactive potential in the fertility and nutrient cycling contexts. The IAA activity and microbial degradation products qualify for a possible activity as soil biostimulants. Quantitative details and possible modes of action are discussed.
Keywords
Preparation 500, biodynamic agriculture, auxin-like activity, hornmanure, biostimulants