Enhancement of Agro-Industrial Waste Composting Process via the Microbial Inoculation: A Brief Review

Composting is an important technology used to treat and convert organic waste into value-added products. Recently, several studies have been done to investigate the effects of microbial supplementation on the composting of agro-industrial waste. According to these studies, microbial inoculation is considered to be one of the suitable methods for enhancing the biotransformation of organic materials during the composting process. This review provides up-to-date research findings on microbial inoculation strategies and their role and functions in enhancing the composting process and the improvement of compost quality. Based on this review, the addition of microorganisms could enhance the composting process such as accelerating the organic matter degradation, mineralization and microbial enzymes activities, and the quality of the end-products such as high germination index. It is important to notice in this strategy that sludge’s microbial consortium is feasible to enhance the composting process in pilot-scale and industrial-scale productions. Besides, it also reduces the cost of compost production. The findings of this review show the various positive impact of microbial inoculation on agro-industrial waste composting which in turn might be useful as a reference for selecting a suitable inoculum based on the type of waste materials.

Development of a consortium-based microbial agent beneficial to composting of distilled grain waste for Pleurotus ostreatus cultivation

Background Pleurotus ostreatus is an edible mushroom popularly cultivated worldwide. Distilled grain waste (DGW) is a potential substrate for P. ostreatus cultivation. However, components in DGW restrict P. ostreatus mycelial growth. Therefore, a cost-effective approach to facilitate rapid P. ostreatus colonization on DGW substrate will benefit P. ostreatus cultivation and DGW recycling. Results Five dominant indigenous bacteria, Sphingobacterium sp. X1, Ureibacillus sp. X2, Pseudoxanthomonas sp. X3, Geobacillus sp. X4, and Aeribacillus sp. X5, were isolated from DGW and selected to develop a consortium-based microbial agent to compost DGW for P. ostreatus cultivation. Microbial agent inoculation led to faster carbohydrate metabolism, a higher temperature (73.2 vs. 71.2 °C), a longer thermophilic phase (5 vs. 3 days), and significant dynamic changes in microbial community composition and diversity in composts than those of the controls. Metagenomic analysis showed the enhanced microbial metabolisms, such as xenobiotic biodegradation and metabolism and terpenoid and polyketide metabolism, during the mesophilic phase after microbial agent inoculation, which may facilitate the fungal colonization on the substrate. In accordance with the bioinformatic analysis, a faster colonization of P. ostreatus was observed in the composts with microbial inoculation than in control after composting for 48 h, as indicated from substantially higher fungal ergosterol content, faster lignocellulose degradation, and higher lignocellulase activities in the former than in the latter. The final mushroom yield shared no significant difference between composts with microbial inoculation and control, with 0.67 ± 0.05 and 0.60 ± 0.04 kg fresh mushroom/kg DGW, respectively (p > 0.05). Conclusion The consortium-based microbial agent comprised indigenous microorganisms showing application potential in composting DGW for providing substrate for P. ostreatus cultivation and will provide an alternative to facilitate DGW recycling.

Deciphering the Mechanisms of Microbe Mediated Drought Stress Alleviation in Wheat

Drought stress adversely influences the crop plants. Herein, present research was designed to elucidate the role of plant growth promoting microbes for amelioration of water stress in wheat. A pot experiment was conducted for screening the microorganisms on the basis of plant growth, chlorophyll and proline content under water stress. Bacillus sp. BT3 and Klebsiella sp. HA9 were found more promising strains that positively influenced the plant growth, chlorophyll and proline status of seedlings under water stress condition. Further, Bacillus sp. BT-3 and Klebsiella sp. HA9 along with check strain (BioNPK) were used for elucidating their detailed effect on morphological, biochemical, physiological and molecular traits to mitigate drought stress in wheat. Microbial inoculation significantly enhanced plant growth, biomass, relative water content, chlorophyll content and root morphological parameters over the uninoculated water stressed (30% FC) control. Likewise, sugar content, protein content and antioxidant enzymes were also significantly enhanced due to microbial inoculation under water stress (30% FC). Microbial inoculation significantly decreased proline, glycine betaine, lipid peroxidation, peroxide and superoxide radicals in wheat over the uninoculated water stressed (30%FC) control. Quantitative real-time (qRT)- PCR analysis revealed that Bacillus sp. BT-3, Klebsiella sp. HA9 and BioNPK inoculation significantly upregulated stress responsive genes (DHN, DREB, L15 and TaABA-8OH) over the uninoculated water stressed (30% F.C.) control. The study reports the potential of Bacillus sp. BT3 and Klebsiella sp. HA9 along with BioNPK in water stress alleviation in wheat which could be recommended as effective biofertilizers.

The Effect of Microbial Inoculation under Various Nitrogen Regimes on the Uptake of Nutrients by Apple Trees

The European Green Deal strategy currently implemented in the EU aims to, among others, reduce the negative impact of fertilization on the environment. One of the solutions influencing the nutritional status of plants and the improvement of soil quality is the use of plant symbiosis with microorganisms. Thus, in this study we investigated the effect of arbuscular mycorrhizal fungi (AMFs) and plant-growth-promoting rhizobacteria (PGPR) colonization on the nutritional status of apple leaves and fruit, depending on the nitrogen treatment. In a fully factorial experiment, trees were grown for nine years with or without AMFs and PGPR. We compared several ammonium nitrate treatments as well as growth without fertilization as a control. The interactions between inoculation and doses of nitrogen fertilization were observed. AMF + PGPR significantly increased the concentration of nitrogen (N), phosphorus (P), and potassium (K) in leaves up to 5%, 23%, and 19%, respectively, depending on the N dosage. Conversely, in uninoculated trees, the nitrogen treatment had a negative impact on the leaf P mineral status. On the other hand, under microbial inoculation conditions, the dose of 100 kg N∙ha−1 diminished the leaf phosphorus content in comparison to other N doses, by a maximum of 9.6%. AMF + PGPR, depending on the N treatment, either did not influence or it decreased the Mg and Ca concentrations in the leaves by maximums of 8% and 15%, respectively. Microbial inoculation had no effect on the acquisition of Ca and Mg by fruits, except for the coupled negative influence of the 100 kg N∙ha−1 treatment. Symbiosis positively conditioned the K in fruits under a specific N regime—100 kg N∙ha−1 divided into two applications during the season and 50 kg N∙ha−1 applied to the herbicide strip, increasing the concentration by approximately 4% and 8%, respectively. This study greatly contributes to our understanding of the benefits of AMF and PGPR on perennials and encourages the future exploration of their effects on apple yield and fruit quality.

Application of Trichoderma viride and Bacillus subtilis Leads to Changes in Antioxidant Enzymes, Proline, and Lipid Peroxidation under Salinity Stress in Chickpea (Cicer arietinum L.)

The study was carried out to evaluate the influence of application of Trichoderma viride and Bacillus subtilis on antioxidant enzymes, proline and lipid peroxidation to decrease the impact of salinity stress on chickpea (Cicer arietinum L.), a salinity sensitive crop. A pot experiment was conducted with contrasting set of genotypes (tolerant vs. sensitive) under salinity stress compared to control soil conditions in completely randomized design with three replications. Microbial inoculation was done through seed priming and application to soil at 20 days after sowing (DAS). Content of antioxidant enzymes, proline, and lipid peroxidation were assessed in leaves at flowering stage. Results showed that antioxidant enzymes viz., catalase, peroxidase, and superoxide dismutase were significantly increased under salinity stress compared to control condition and they were further increased with application of microbes either as seed priming alone or in combination with soil application at 20 DAS in both the genotypes under saline as well as control conditions. The content of lipid peroxidation increased significantly under salinity stress, and it was stronger pronounced in sensitive genotype while the lipid peroxidation content was decreased by application of microbes. Proline content increased under salinity stress, and it was further enhanced by the microbial inoculation. The study thus conclusively proved that Bacillus subtilis and Trichoderma viride positively increased content of antioxidant enzymes, proline, and lipid peroxidation in leaves of chickpea grown under salinity stress conditions. The best microbe species was Trichoderma viride as seed priming plus soil application. This can be an important additional approach to decrease the impact of salinity stress on chickpea crop.

Malus Antioxidant Metabolism Following Bacterial–Fungal Inoculation in Organic Farming: From Root to Fruit

This study investigated the antioxidant status of roots, leaves, and fruit upon microbial inoculation (AMF+PGPR, arbuscular mycorrhizal fungi, and plant growth-promoting rhizobacteria, respectively) of young organically farmed apple trees over two growing seasons. Three cultivars—‘Topaz’, ‘Chopin’, and ‘Odra’—were selected to test the relationship between inoculation and enzymatic and non-enzymatic antioxidant components. The antioxidant metabolism was highly dependent on tissue type and growing season. The greatest effect on antioxidant status following application of the inoculum was found in roots, then leaves, but it was almost negligible in fruit. Roots were influenced most by application of the inoculum in the first growing season, while leaves were influenced most in the second season. Considerable differences between the inoculated and control plants were found for root glutathione reductase (GR) and catalase (CAT) activity, as well as glutathione and ascorbate contents; root phenolics were not influenced by inoculation. In the case of leaves, effect of microbial inoculation on GR activity was revealed in the first growing season, while for global phenolics in the second season, and only the concentration of glutathione was significantly higher in the leaves of inoculated trees in both growing seasons. Leaf ascorbate content and CAT activity were not influenced by the microbial inoculation. The control and inoculated trees expressed a similar total antioxidant capacity, irrespective of the tissue type tested. Furthermore, the response of the cultivars to inoculation varied and also changed in consecutive growing seasons. Based on this study, it is likely that the effect of microbial inoculum as a tool for enhancing health-promoting properties in the fruit of perennial plants is weaker than that described for vegetables where different plant organs are edible.

133 The Potential for Maternal Nutrition to Influence, Health, Development and Subsequent Lifetime Performance of the Pig

The global population is continuing to grow at a rapid rate leading to increased need for meat and milk products. The pig industry will need to adapt and expand to meet this demand. Improving the productivity of the pig industry is therefore vital in ensuring sustainable growth in the future. The use of dietary additives is a means to improve this animal productivity, however, the most appropriate time to provide dietary additives to ensure maximum benefit with the lowest cost is an area that warrants further exploration. The early-life period is a vital time of physiological, transcriptional, and microbial changes that have a stark impact on lifetime productivity. This early lifetime point provides an opportunity to aid development and impart lifetime alterations and improve animal productivity and health. These changes can be applied by dietary and management interventions to the pig itself or to the dam. The dam is a key influence on the development of the progeny as the primary site of microbial inoculation and is therefore, an interesting target for dietary intervention. With increased legislative and environmental constraints through the ban on antibiotics and the phasing out of zinc-oxide in the EU, there is a need to identify viable natural alternatives to increase productivity particularly in the post weaning period. A wealth of chemodiversity exists in nature in plants and animals developing protective molecules to survive in varying complex biosystems. Our research has established the potential of feeding naturally sustainable bioactives to improve animal performance and health. This talk will explore the strategy of feeding these natural bioactives to the dam to improve lifetime performance of the progeny.