Effects of vermicomposted spent mushroom compost on growing medium characteristics, plant growth, yield and abiotic stress tolerance

Treatment of agricultural biodegradable wastes and by-products can be carried out using composting or vermicomposting, or a combination of both treatment methods, to create a growing medium amendment suitable for horticultural use. When compared to traditional compost-maturation, vermicompost-maturation resulted in a more mature growing medium amendment i.e. lower C/N and pH, with increased nutrient content and improved plant growth response, increasing lettuce shoot fresh and dry weight by an average of 15% and 14%, respectively. Vermicomposted horse manure compost was used as a growing medium amendment for lettuce and was found to significantly increase lettuce shoot and root growth, and chlorophyll content. When used as a growing medium amendment for tomato fruit production, vermicomposted spent mushroom compost increased shoot growth and marketable yield, and reduced blossom end rot in two independent studies. Vermicompost addition to peat-based growing media increased marketable yield by an average of 21%. Vermicompost also improved tomato fruit quality parameters such as acidity and sweetness. Fruit sweetness, as measured using Brix value, was significantly increased in fruits grown with 10% or 20% vermicompost addition by 0.2 in truss one and 0.3 in truss two. Fruit acidity (% citric acid) was significantly increased in plants grown with vermicompost by an average of 0.65% in truss one and 0.68% in truss two. These changes in fruit chemical parameters resulted in a higher tomato fruit overall acceptability rating as determined by a consumer acceptance panel. When incorporated into soil, vermicomposted spent mushroom compost increased plant growth and reduced plant stress under conditions of cold stress, but not salinity or heat stress. The addition of 20% vermicompost to cold-stressed plants increased plant growth by an average of 30% and increased chlorophyll fluorescence by an average of 21%. Compared to peat-based growing medium, vermicompost had consistently higher nutrient content, pH, electrical conductivity and bulk density, and when added to a peat-based growing medium, vermicomposted spent mushroom compost altered the microbial community. Vermicompost amendment increased the microbial activity of the growing medium when incorporated initially, and this increased microbial activity was observed for up to four months after incorporation when plants were grown in it. Vermicomposting was shown to be a suitable treatment method for agricultural biodegradable wastes and by-products, with the resulting vermicompost having suitable physical, chemical and biological properties, and resulting in increased plant growth, marketable yield and yield quality, when used as an amendment in peat-based growing medium.

Archaea appear to dominate the microbiome of Inflatella pellicula deep sea sponges

Microbes associated with marine sponges play significant roles in host physiology. Remarkable levels of microbial diversity have been observed in sponges worldwide through both culture-dependent and culture-independent studies. Most studies have focused on the structure of the bacterial communities in sponges and have involved sponges sampled from shallow waters. Here, we used pyrosequencing of 16S rRNA genes to compare the bacterial and archaeal communities associated with two individuals of the marine sponge Inflatella pellicula from the deep-sea, sampled from a depth of 2,900 m, a depth which far exceeds any previous sequence-based report of sponge-associated microbial communities. Sponge-microbial communities were also compared to the microbial community in the surrounding seawater. Sponge-associated microbial communities were dominated by archaeal sequencing reads with a single archaeal OTU, comprising similar to ∼60% and similar to ∼72% of sequences, being observed from Inflatella pellicula. Archaeal sequencing reads were less abundant in seawater (similar to ∼11% of sequences). Sponge-associated microbial communities were less diverse and less even than any other sponge-microbial community investigated to date with just 210 and 273 OTUs (97% sequence identity) identified in sponges, with 4 and 6 dominant OTUs comprising similar to ∼88% and similar to ∼89% of sequences, respectively. Members of the candidate phyla, SAR406, NC10 and ZB3 are reported here from sponges for the first time, increasing the number of bacterial phyla or candidate divisions associated with sponges to 43. A minor cohort from both sponge samples (similar to ∼0.2% and similar to ∼0.3% of sequences) were not classified to phylum level. A single OTU, common to both sponge individuals, dominates these unclassified reads and shares sequence homology with a sponge associated clone which itself has no known close relative and may represent a novel taxon.

Interactions between nematodes, potato and soil-borne micro-organisms and their effect on the management of potato cyst nematodes

Potato cyst nematodes (PCN) cause significant damage to the potato crop worldwide and growers experience economic losses related to yield loss and the cost of control measures. Experiments were set up to further elucidate the complex tritrophic PCNpotato-soil bacteria relationship. Bacterial strains isolated from the sugar beet rhizosphere were shown to be hatch active towards Globodera pallida and to be capable of successfully colonising the sugar beet rhizosphere when applied exogenously. A trap-crop system, based on these isolates, was proposed. Ridge and bulk soil taken from a commercial potato field were incubated with sterile potato root leachate (sPRL) and subsequent in vitro hatching assays showed that PCN hatch was influenced by microorganisms present in the ridge, but not in the bulk soil. Community level physiological profiling (CLPP) of ridge and bulk soil, using BIOLOG EcoplatesTM, demonstrated differences in bacterial functional diversity between the two soil types. An investigation of the inter-species competition between G. pallida and G. rostochiensis showed that G. pallida performed significantly better, in terms of multiplication rate, in competition with G. rostochiensis compared to its multiplication rate in single-species populations. Effectively removing the early hatch of G. rostochiensis in pot trials led to the removal of this competitive advantage of G. pallida suggesting that this advantage was due, at least in part, to morphological changes to the root caused by the early hatching of G. rostochiensis.