Preface

The genus *Aspergillus* consists of a diverse group of airborne species with environmental and public health impacts. The members of this genus are cosmopolitan fungi frequently found in soil as the main reservoir and they are responsible for food spoilage, mycotoxin contamination, and various types of human and animal mycoses. Moreover, they are rich sources of beneficial metabolites such as antibiotics, organic acids, enzymes, and additives. At present, there are more than 350 identified species in the genus, of which around 20 species are known to be involved in the etiology of *Aspergillus*-related diseases under the common name "aspergillosis." Mode of infection is the inhalation of airborne conidia, exposure to contaminated water, and nosocomial infections. This book, which includes six chapters over two sections, discusses different aspects of the genus *Aspergillus*, including *Aspergillus–*host interactions to immunopathogenesis of aspergillosis, mycotoxin production, and industrial applications of the beneficial species.

Chapter 1 is an introductory chapter that contains useful information about all sections and chapters of the book. Chapter 2 discusses the environmental and clinical importance of *Aspergillus–*human interactions with a special focus on host immune status and previous underlying diseases as important determinants of clinical outcomes and disease spectra of aspergillosis. Chapter 3 examines the immunopathogenesis of aspergillosis with emphasis on the route of entry of etiologic *Aspergillus* species, and the function of pulmonary host defense in the clearance of infective conidia. In this context and in conditions of poor host immune response, where the neutrophils and macrophages fail to recognize the etiologic fungus, *Aspergillus* conidia attack and destroy airway epithelium. Chapter 4 reviews the role of aflatoxin in *A. flavus* resilience to stress with special attention to *Aspergillus* section *Flavi* in relation to producing the aflatoxins, secondary metabolites toxic to humans and animals. Chapter 5 examines why these fungi produce aflatoxins and the role of this mycotoxin in pathogenicity or in niche competition of producing fungus. The chapter also addresses another amazing aspect of *Aspergillus* research, the relationship between mycovirus-containing *A. flavus* and acute lymphoblastic leukemia as carcinogenesis beyond mycotoxin production. Finally, Chapter 6 discusses the industrial importance of members belonging to the genus *Aspergillus* with a focus on the ability of important species to green synthesis of functional nanomaterials with potential application in agriculture and medicine.

We would like to thank all authors for their invaluable contributions. We are also grateful to the staff at IntechOpen, especially Ms. Karmen Ðaleta, who kindly assisted us in the arrangement of the book and scheduling of our activities. MR is thankful to the Polish National Agency for Academic Exchange (NAWA) for

financial support (Project No. PPN/ULM/2019/1/00117/A/DRAFT/00001) to visit the Department of Microbiology, Nicolaus Copernicus University, Toruń, Poland.

#### **Mehdi Razzaghi-Abyaneh**

Department of Mycology, Pasteur Institute of Iran, Tehran, Iran

#### **Mahendra Rai**

Department of Microbiology, Nicolaus Copernicus University, Torun, Poland
