Microbial Biostimulants for Sustainable Agriculture and Environmental Bioremediation

Inamuddin, Charles Oluwaseun Adetunji, Mohd Imran Ahamed, Tariq Altalhi, Inamuddin, Charles Oluwaseun Adetunji, Mohd Imran Ahamed, Tariq Altalhi

• Editore: CRC Press
• Anno: 2022
• ISBN:
  9781000600520
• Edizione: 1
• Argomento: Tecnologia e ingegneria
• Categoria: Agricoltura sostenibile

Today, the agriculture industry is confronted with simultaneous issues of how to fully embrace mass production of safer food in terms of both quality and quantity. Most industries are concerned with avoiding significant levels of soil pollution and environmental threats as a result of the excessive and harmful use of synthetic products on crops. Therefore, there is a need to adopt sustainable technological innovations that can ensure the sustainability of agricultural production systems.

Microbial Biostimulants for Sustainable Agriculture and Environmental Bioremediation discusses the benefits, challenges, and practical applications of eco-friendly biotechnological techniques using biostimulants derived from beneficial microorganisms. The chapters cover the use of these organisms to increase crop production, enhance soil fertility and maintain soil health, create crop and plant tolerance to different abiotic stressors, release required nutrients to the soil, increase resistance to plant pathogens/pests, improve nutrient use efficiency of crops, and rejuvenate polluted environments.

FEATURES

• 
  
  

• Explores the physiological, morpho-anatomical, and biochemical molecular plant rejoinders involved in stimulating crop productivity

• 
  
  

• Provides information on the physiological, cellular, and molecular modes of action underlying microbial biostimulant interfaces

• 
  
  

• Summarizes methods and approaches for executing microbial stimulant technology

• 
  
  

• Outlines numerous environmental management and remediation strategies

This book is an ideal resource for researchers, engineers, and academics working in soil science, crop science, water remediation, microbiology, and biotechnology.

1 Microbial Biostimulants for Tolerance to Abiotic and Biotic Stresses in Mushrooms

Olga Tsivileva

Institute of Biochemistry and Physiology of Plants and Microorganisms, Saratov Scientific Centre of the Russian Academy of Sciences

DOI: 10.1201/9781003188032-1

Contents

• 1.1 Introduction
• 1.2 PGPR Interactions with Mycorrhizal Fungi
• 1.3 PGPR Interactions with Cultivable Mushrooms
• 1.4 Fungi–Azospirillum Interactions
• 1.5 Conclusions
• Acknowledgments
• References

1.1 Introduction

Mushrooms, the macromycete flora representatives, play a significant role as food and biological subjects capable of producing many physiologically active compounds. Numerous scientific works are dedicated to the investigation of mushrooms’ physiology, ecology, biochemistry and biotechnology. Owing to their commercialization, many edible mushrooms are readily available [1] and provide a precious source of nutritive food ingredients. Broad spectrum and diversity of mushrooms have led to an exciting pharmacological potentiality of bioactive preparations from their cultivation. The discovery that a lot of mushrooms produce a broad range of medicinally useful metabolites [2] was followed by the intense development of biomedicinal area of fungi exploitation [3]. For instance, various chemical agents entering the composition of mycelia exhibit antiviral activity against many viruses pathogenic for humans [4], which currently presents a great pharmaceutical challenge. Thus, in view of the great biotechnological interest in wide-scale cultivation of basidiomycetes, the factors of biological origin that promote their growth, including microbial biostimulants, are of major importance.

One of the preferential lines in the current mushroom science is decoding the ways of inducement of biochemical processes of the basidiomycetes’ ontogenesis. Complex physiological and biochemical processes that occur at growth and development of fungus organisms are determined largely by the biotic factors of environment, which must be studied in detail. That provides the necessity of studying the joint cultivation with bacteria in relation to the processes of cytodifferentiation and morphogenesis of mushrooms, and of revealing the role of these factors in the vital activity of fungal cultures. The research of such kind is useful for the directive selection of effective inducers enhancing the stress resistivity of edible cultivable mushrooms, as it is true for plants. Understanding the mechanisms and peculiarities of associative interactions at the bacterial–fungal communities could assist in developing more efficient and productive methods of growing the cultivable edible and medicinal mushrooms.

Hence, the challenging problem is the development of ecologically safe ways of applying the growth-promoting bacteria and bioactive substances of bacterial origin to the technologies of enhancing the resistivity of cultivable basidiomycetes against the pathogenic bacterial and lower-fungal contamination, and to the technologies of controlling the abundance of the contaminating microflora representatives in the industrial mushroom growing.

Analyzing the current literature in respect of works on xylotrophic basidiomycetes and bacteria co-cultivation shows the absolute insufficiency of these problems under consideration, in spite of the high potentiality of fundamental and applied research in this area. Bacteria from the genus Azospirillum are rhizospheric microorganisms that enhance plant growth and development via nitrogen fixation and hormone production [5]. Worthy to mention is the bactericidal and fungicidal activity of azospirilla against several bacteria and lower micromycetes [6,7]. Systemic research into the basidiomycetes joint culture with bacteria from the genus Azospirillum under the artificial conditions was scarce in the literature until studies were initiated at the Lab. of Microbiology of IBPPM RAS in relation to the double culture of Lentinula edodes (shiitake mushroom) strain F-249 and Azospirillum brasilense Sp7 [8,9]. The effect of A. brasilense Sp7 on growth and morphological peculiarities of L. edodes F-249 was studied [10,11]; therewith, the reasons for enhanced development of mycelium remain unclear. Currently, the search for appropriate, effective strains of azospirilla in respect of mushrooms from different systematic groups becomes a necessity.

1.2 PGPR Interactions with Mycorrhizal Fungi

Bacteria involved in the associative and symbiotic relations with plant roots are known to contribute positively to plant metabolism and growth parameters. Such bacteria are called “plant growth-promoting rhizobacteria” (PGPR), i.e., rhizobacteria facilitating plant growth [12–15]. Phytostimulating properties of such PGPR representatives as Azospirillum are well studied [16].

PGPR capable of influencing positively the development of mycorrhizal structures or the mycorrhizal fungi, on the formation of mycorrhizal symbiosis, constitute the group “mycorrhization helper bacteria” (MHB) [17–19]. The intense citation of works dealt with mycorrhizal fungi is out of the scope of this review. That is, follow only few representative examples. Pseudomonas fluorescens could exert a positive effect on the mycelium development of the ectomycorrhizal fungus Laccaria bicolor in vitro by means of production of thiamine assimilated by the fungus. At the same time, L. bicolor is capable of accumulating trehalose in hyphae, which promotes the growth of colony of P. fluorescens. Both organisms demonstrate synergetic interactions important for their vital activity [20]. Endophytic bacteria Pseudomonas aeruginosa and Burkholderia cepacia form associations with the mycorrhizal fungi Glomus intraradices and Glomus clarum and are capable of influencing positively the mycelium of these fungi [21]. Even in the absence of host plant, the mutual positive effects of mycorrhizal fungi and MHB are manifested [22]. МНВ could be non-specific and promote the mycorrhiza formation by various fungi [23].

Reasonability of studying different aspects of favorable MHB action on the mycorrhizal basidiomycetes is commonly recognized; however, the mechanisms responsible for the favorable effect of soil bacteria on the mycorrhizal fungi are investigated insufficiently [24,25].

1.3 PGPR Interactions with Cultivable Mushrooms

Putting into practice the biological techniques of mycelium growth stimulation, and its protection from the interfering microflora, would allow one to improve the growing technology via the less prolonged cultivation period and concurrent suppression of the contaminating microflora. The research into the microbial populations isolated from the surface of mycelium during the fruit body formation of Pleurotus ostreatus was performed. Dominating in bacterial community, Pseudomonas spp. appear to facilitate fruiting when being used as inoculum for pure cultures of the basidiomycete in vitro [26]. In double culture of the same basidiomycete with P. fluorescens, the formation of a bacterial biofilm was observed. The biofilm was successfully applied by the authors [27] in their experiments with tomato plants. In the joint cultivation of P. ostreatus with the strain of diazotroph Bradyrhizobium elkanii, not only the dense colonization of mycelium by bacteria, but also the active process of nitrogen fixation within the biofilm on hyphae was observed. More recently, the same mushroom has attracted the attention of Febriansyah and co-authors [28]. They presented a work on the impact of the bacterial cell-free extract on P. ostreatus mycelium development. Nineteen bacteria strains were involved, leading to an increase in mycelial growth; nevertheless, there was no significant influence statistically. Indole-3-acetic acid content was assayed with three chosen bacterial isolates: Bacillus cereus, Bacillus aryabhattai and Acinetobacter pittii [28], the highest content being produced by Bacillus aryabhattai strain B8W22.

Agaricus bisporus (champignon) is an edible mushroom cultivated for food worldwide. A. bisporus vegetative growth should be done at compost, and the presence of bacteria in the casing layer greatly influences the fruit body initiation of this mushroom [29]. In the latter work, greenhouse experiments were conducted using numerous bacterial isolates; 60 rhizobia and 30 pseudomonades strains were tested to estimate the effect of these plant growth-promoting bacteria (PGPB) on mushroom fruit body formation. Rhizobial bacteria were Sinorhizobium meliloti and Rhizobium leguminosarum biovar phaseoli, and pseudomonades belonged to Pseudomonas fluorescens species. The results obtained testified to the increased yield and quality of A. bisporus fruit bodies provided that the growth-promoting bacteria were implemented in this edible mushroom cultivation at compost. Thus, PGPR occurred beneficial in the production of healthy food [29].

Zarenejad and co-workers [30] evaluated the prospective bacteria with mushroom growth-promoting features from soils sampled at the bisporic champignon farms. Casing layers used for A. bisporus fruit body production contained two strains as potent MGPB, which were isolated and both assigned to genus Pseudomonas [30]. It seems obvious that the bacteria inhabiting the casing soil and compost should move onto fungal mycelium and subsequently occur within the basidiomes of Agaricus species mushrooms. That is why the microbes in the mushroom fruit bodies have received a little attention. Xiang and co-authors reported [31] on the diversity of bacterial isolates sampled in basidiomes of bisporic champignon. Among 55 strains of bacteria belonging to seven biological families, Bacillus spp. was a dominant genus in this mushroom. But only further studies could clarify whether these isolates are capable of serving as a growth-promoting factor for A. bisporus.

Fifty-six specimens were obtained from the culture substrate of another species of Agaricus, A. blazei, in order to estimate the impact of the isolated bacteria on the development of fungal mycelium and the yield of fruit bodies [32]. Few isolates were selected and shortlisted on the grounds of the effect on this mushroom productivity: Agaricicola taiwanensis, Advenella incenata, Curtobacterium citreum, Gordonia hydrophobica, Streptomyces violaceorubidus and Microbacterium humi. Several of the tested species promoted A. bla...