Editorial Microbial Enzymes and Their Applications in Industries and Medicine 2016 Periasamy Anbu, 1 Subash C. B. Gopinath, 2,3 Bidur Prasad Chaulagain, 4 and Thangavel Lakshmipriya 1,2 1 Department of Biological Engineering, College of Engineering, Inha University, Incheon 402-751, Republic of Korea 2 Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, 01000 Kangar, Perlis, Malaysia 3 School of Bioprocess Engineering, Universiti Malaysia Perlis, 02600 Arau, Perlis, Malaysia 4 Directorate of Research and Training, Himalayan College of Agricultural Sciences and Technology (HICAST), P.O. Box 25535, Kalanki, Kathmandu, Nepal Correspondence should be addressed to Periasamy Anbu; anbu25@yahoo.com and Subash C. B. Gopinath; subash@unimap.edu.my Received 14 December 2016; Accepted 4 January 2017; Published 28 March 2017 Copyright © 2017 Periasamy Anbu et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Enzymes are biocatalysts that play an important role in metabolic and biochemical reactions [1]. Microorganisms are the primary source of enzymes, because they are cultured in large quantities in short span of time and genetic manipula- tions can be done on bacterial cells to enhance the enzyme production [2–4]. In addition, the microbial enzymes have been paid more attention due to their active and stable nature than enzymes from plant and animal [2–4]. Most of the microorganisms are unable to grow and produce enzyme under harsh environments that cause toxicity to microor- ganisms. However, some microorganisms have undergone various adaptations enabling them to grow and produce enzymes under harsh conditions [5, 6]. Recently several lines of study have been initiated to isolate new bacterial and fungal strains from harsh environments such as extreme pH, temperature, salinity, heavy metal, and organic solvent for the production of diferent enzymes having the properties to yield higher [6–9]. Tis special issue covers six articles including one review article, highlighting the importance and applications of biotechnologically and industrially valuable microbial enzymes. Tere are redundancies in genetic code that amino acid might be encoded by multiple synonymous codons. Tis scenario gives an opportunity to choose a codon other than the naturally occurring one in the genome to optimize the production with heterologous expression system. Codon optimization in another sense is a guided mutagenesis in the gene expression system which can be utilized for the benefts of human kind, ranging from industrial agricul- ture to medicine. J. Wang et al. have applied a series of strategies to improve the expression level of recombinant endo--1,4-xylanase from Aspergillus usamii in Pichia pas- toris. Te endo--1,4-xylanase gene (xynB) from A. usamii was optimized for expression in P. pastoris. Teir analysis showed the codon for amino acid residues in P. pastoris is diferent from the original codon of A. usamii. Tus they replaced the codons in endo--1,4-xylanase gene to ft to the cellular environment of P. pastoris. Similarly they optimized the codons of Vitreoscilla hemoglobin gene (vhb) to ft to heterologous expression system in P. pastoris cell system. While optimizing codons they replaced the AT-rich stretches with GC-rich stretches, because G+C content afects the secondary structure of mRNA and infuences the expression level of heterologous gene. Totally, 105 and 57 amino acids were optimized in native xynB and vhb, respectively. Besides optimizing the genetic system, J. Wang et al. have also opti- mized the environment to express those recombinant genes. Te codon optimized vhb gene has signifcantly improved the oxygen availability for host P. pastoris since oxygen supply is one of most critical factors for the cell growth and heterologous protein expression in recombinant P. pastoris. By optimizing the temperature efect on the system they increased the xylanase production combined with higher cell viability. Overall, this work has supported the notion of Hindawi BioMed Research International Volume 2017, Article ID 2195808, 3 pages https://doi.org/10.1155/2017/2195808