Meet the editors

Dr. Jianqiang Lin has been a professor at the State Key Laboratory of Microbial Technology (SKLMT), Shandong University, China, since 2003. He obtained a Ph.D. in 1998 under a China-Japan government cooperation program on Ph.D. education and completed his thesis research at Osaka University, Japan. In 2000, he was a visiting researcher at Inha University, Korea. His research interests include molecular biology of acidophiles,

microbial technology, and bioprocess bioengineering.

Dr. Linxu Chen has a Ph.D. in Microbiology from the State Key Laboratory of Microbial Technology (SKLMT), Shandong University, China. He completed his postdoctoral research at Louisiana State University, USA. His research interests include gene transfer systems and gene-editing technology of chemoautotrophic acidophilic bacteria, metabolic and adaptive mechanisms of bioleaching bacteria, and genetic engineering and synthetic

biology of bioleaching bacteria.

Dr. Jianqun Lin is Director of the Shandong Society for Microbiology, China. He obtained a Ph.D. from the Chinese Academy of Sciences in 1997. He was a visiting researcher at Osaka University, Japan, in 1997–1998, and completed his postdoctoral research at the Uniformed Services University of Health Science, USA. His research interests include biological resources development of acidophiles in acid mine environments, bacteria–mineral interac-

tion and the sulfide ore bioleaching process, and the development of high-efficiency bioleaching techniques.

Contents

**Preface XI**

**Chapter 1 1**

**Chapter 2 9**

**Chapter 3 21**

**Chapter 4 37**

**Chapter 5 51**

**Chapter 6 63**

Introductory Chapter: The Important Physiological Characteristics

Two-Component Systems in the Regulation of Sulfur and Ferrous

Thriving at Low pH: Adaptation Mechanisms of Acidophiles

Quorum Sensing of Acidophiles: A Communication System

*Acidithiobacillus* Its Application in Biomining Using a Quorum

Immunomodulatory Potential of *Lactobacillus acidophilus*:

*by Asha Bhardwaj, Leena Sapra, Bhupendra Verma* 

*by Xueyan Gao, Jianqiang Lin, Linxu Chen, Jianqun Lin* 

and Industrial Applications of Acidophiles *by Linxu Chen, Jianqun Lin and Jianqiang Lin*

Iron Oxidation in Acidophilic Bacteria

*by Lifeng Li and Zhaobao Wang*

Sensing Modulation Approach

Implications in Bone Health

*and Rupesh K. Srivastava*

*by Juan Carlos Caicedo and Sonia Villamizar*

*by Xianke Chen*

in Microorganisms

*and Xin Pang*

## Contents


Preface

Acidophiles, as an important class of extremophiles, have attracted attention for their scientific significance and application value. Acidophiles are microorganisms that thrive in acidic conditions and can be found in Bacteria, Archaea, and Eukarya. Acidophiles can be identified in both terrestrial and marine environments, including acid mine drainage (AMD) from metal and coal mines, iron-sulfur mineral mines, hot springs, and sediments. In these acidic ecosystems, acidophiles could participate in the element cycles (sulfur, iron, etc.) and promote the generation of the acid environment and formation of the acid micro-ecosystem. Acidophiles can also be found in the human body. Research on acidophiles can help us understand the diversity, adaptation, and functions of these microorganisms and contribute to the development and application of new biotechnologies for resolving problems of resource exploitation, pollution, and human disease. This book provides breakthroughs and insights into the research on acidophiles. Chapter 1 introduces acidophiles and their important physiological characteristics and industrial applications. Chapter 2 discusses the two-component signal systems in the regulation of sulfur and ferrous iron oxidation in acidophilic bacteria. Chapter 3 focuses on the acid-resistance adaptation mechanisms in acidophiles. Chapter 4 introduces the quorum sensing system (QS)-mediated communication mode in chemoautotrophic acidophilic bacteria and the function of QS in the regulation of bacterial sulfur oxidation, ferrous iron oxidation, and mineral oxidation. Chapter 5 discusses the application of QS and QS signals on bioleaching industries. The final chapter deals with acidophiles in human health, including the immunomodulatory potential of *Lactobacillus acidophilus* and its potential role as a therapeutic for the management

> **Jianqiang Lin, Linxu Chen and Jianqun Lin** State Key Laboratory of Microbial Technology,

> > Shandong University, Qingdao, China

of inflammation-induced bone disorders.
