RESUMEN
Salinity is a serious environmental factor that impedes crop growth and drastically reduces yield. This study aimed to investigate the potential of halophilic archaea isolated from the Rann of Kutch to alleviate the negative impact of salinity on crop growth and yield. The halophilic archaea, which demonstrated high tolerance to salinity levels up to 4.5 M, were evaluated for their ability to promote plant growth in both salt-tolerant and salt-susceptible wheat cultivars. Our assessment focused on their capacity to solubilize essential nutrients, including phosphorus (14-61 mg L-1), potassium (37-78 mg L-1), and zinc (8-17 mg L-1), as well as their production of the phytohormone IAA (17.30 to 49.3 µg ml-1). To conduct the experiments, five wheat cultivars (two salt-tolerant and three salt-susceptible) were grown in triplicates using soft MS agar tubes (50 ml) and pots containing 10 kg of soil with an electrical conductivity (EC) of 8 dSm-1. Data were collected at specific time points: 21 days after sowing (DAS) for the MS agar experiment, 45 DAS for the pot experiment, and at the time of harvest. In the presence of haloarchaea, the inoculated treatments exhibited significant increases in total protein (46%), sugar (27%), and chlorophyll (31%) levels compared to the un-inoculated control. Furthermore, the inoculation led to an elevated accumulation of osmolyte proline (31.51%) and total carbohydrates (27.85%) while substantially reducing the activity of antioxidant enzymes such as SOD, catalase, and peroxidase by 57-76%, respectively. Notably, the inoculated treatments also showed improved plant vegetative growth parameters compared to the un-inoculated treatments. Interestingly, the positive effects of the halophilic archaea were more pronounced in the susceptible wheat cultivars than in the tolerant cultivars. These findings highlight the growth-promoting abilities of the halophilic archaeon Halolamina pelagica CDK2 and its potential to mitigate the detrimental effects of salinity. Consequently, further evaluation of this halophilic archaeon under field conditions is warranted to explore its potential use in the development of microbial inoculants.
RESUMEN
Modern agriculture is primarily focused on the massive production of cereals and other food-based crops in a sustainable manner in order to fulfill the food demands of an ever-increasing global population. However, intensive agricultural practices, rampant use of agrochemicals, and other environmental factors result in soil fertility degradation, environmental pollution, disruption of soil biodiversity, pest resistance, and a decline in crop yields. Thus, experts are shifting their focus to other eco-friendly and safer methods of fertilization in order to ensure agricultural sustainability. Indeed, the importance of plant growth-promoting microorganisms, also determined as "plant probiotics (PPs)," has gained widespread recognition, and their usage as biofertilizers is being actively promoted as a means of mitigating the harmful effects of agrochemicals. As bio-elicitors, PPs promote plant growth and colonize soil or plant tissues when administered in soil, seeds, or plant surface and are used as an alternative means to avoid heavy use of agrochemicals. In the past few years, the use of nanotechnology has also brought a revolution in agriculture due to the application of various nanomaterials (NMs) or nano-based fertilizers to increase crop productivity. Given the beneficial properties of PPs and NMs, these two can be used in tandem to maximize benefits. However, the use of combinations of NMs and PPs, or their synergistic use, is in its infancy but has exhibited better crop-modulating effects in terms of improvement in crop productivity, mitigation of environmental stress (drought, salinity, etc.), restoration of soil fertility, and strengthening of the bioeconomy. In addition, a proper assessment of nanomaterials is necessary before their application, and a safer dose of NMs should be applicable without showing any toxic impact on the environment and soil microbial communities. The combo of NMs and PPs can also be encapsulated within a suitable carrier, and this method aids in the controlled and targeted delivery of entrapped components and also increases the shelf life of PPs. However, this review highlights the functional annotation of the combined impact of NMs and PPs on sustainable agricultural production in an eco-friendly manner.
RESUMEN
The production of petroleum-based plastics increased dramatically following industrialization. Because of multifaceted properties such as durability, thermostability, water resistance, and many others, these plastics have become an indispensable part of daily life. However, while improving people's quality of life, indiscriminate use of plastics has caused pollution and raised environmental concerns. To address this situation and reduce environmental risks, microbially produced biopolymers such as poly-3-hydroxyalkanoates can be used to make bioplastics that are completely biodegradable under normal environmental conditions. At the moment, the cost of bioplastic production is high when compared to petroleum-based plastics, so alternate strategies for making the bioplastic process economical are urgently needed. Agricultural waste is abundant around the world and can be efficiently used as a low-cost renewable feedstock after pretreatment and enzymatic hydrolysis. Fungi are well known as primary degraders of lignocellulosic waste, and this property was used in the current study to enzymatically hydrolyze the pretreated paddy straw for the production of reducing sugars, which were then used in the microbial fermentation for the production of PHB. In this study, Aspergillus nidulans was used to advance a low-cost and efficient enzyme hydrolysis system for the generation of reducing sugars from lignocellulosic biomass. For the production of the holocellulosic enzyme complex, the fungus was grown on wheat straw with Reese mineral medium as a wetting agent. After 216 h of solid-state fermentation at 30 °C, pH 6.0, the enzyme extract from A. nidulans demonstrated the highest activity, CMCase 68.58 (± 0.55), FPase 12.0 (± 0.06), Xylanase 27.17 (± 0.83), and ß-glucosidase 1.89 (± 0.037). The initial pH, incubation temperature, and time all had a significant impact on final enzyme activity. Enzymatic hydrolysis of pretreated paddy straw produced reducing sugars (8.484 to 30.91 gL-1) that were then used to produce poly(3-hydroxybutyrate) using halophilic bacterial isolates. Burkholderia gladioli 2S4R1 and Bacillus cereus LB7 accumulated 26.80% and 20.47% PHB of the cell dry weight, respectively. This suggests that the holocellulosic enzyme cocktail could play a role in the enzymatic hydrolysis of lignocellulosic materials and the production of PHA from less expensive feedstocks such as agricultural waste.
RESUMEN
Microorganisms inhabiting bulk soil and rhizosphere play an important role in soil biogeochemical cycles leading to enhanced plant growth and productivity. In this context, the role of bacteria is well established, however, not much reports are available about the role archaea plays in this regard. Literature suggests that archaea also play a greater role in nutrient cycling of carbon, nitrogen, sulfur, and other minerals, possess various plant growth promoting attributes, and can impart tolerance to various abiotic stresses (especially osmotic and oxidative) in areas of high salinity, low and high temperatures and hydrogen ion concentrations. Thermoacidophilic archaea have been found to potentially involve in bioleaching of mineral ores and bioremediation of chemical pollutants and aromatic compounds. Looking at immense potential of archaea in promoting plant growth, alleviating abiotic stresses, and remediating contaminated sites, detailed studies are required to establish their role in different ecological processes, and their interactions in rhizosphere with plant and other microflora (bacteria and fungi) in different ecosystems. In this review, a brief discussion on archaea from the agro-ecological point of view is presented.