Total protease sales represent more than 60% of all industrial enzyme sales in the world. In modern society, the proteases are widely used. Proteases are used in the detergent industry, leather industry, and also for pharmaceutical applications, such as digestive drugs and anti-inflammatory drugs [13–18]. In 1960, Dane first isolated alkaline protease from Bacillus licheniformis. So far, it is still found that microorganisms are the most suitable resources for protease production. In 1972, Nobou Kato isolated a new type of alkaline protease from marine Psychrobacter, and since then quite a few proteases have been continually obtained from marine microorganisms. An alkaline protease, previously isolated from a symbiotic bacterium found in the Gland of Deshayes of a marine shipworm, was evaluated as a cleansing additive [19]. Qiu et al. selected 30 kinds of marine bacteria from the sea water, mud, fish and other samples; after UV mutagenesis they isolated the N1–35 strain, this strain produced protease that had significant advantages compared with the terrestrial ones [20]. A yeast strain (Aureobasidium pullulans) with a high yield of alkaline protease was isolated from sea saltern of the China Yellow Sea by Chi et al. in 2007, and the maximum production of enzyme was 623.1 U/mg protein (7.2 U/mL) [21]. In 2009, Bacillus mojavensis A21 producing alkaline proteases was isolated from seawater by Haddar et al., and they purified two detergent-stable alkaline serine-proteases (BM1 and BM2) from this strain. Both proteases showed high stability towards non-ionic surfactants. In addition, both of them showed excellent stability and compatibility with a wide range of commercial liquid and solid detergents[22].

Lipases are ubiquitous enzymes that catalyze the breakdown of fats and oils with subsequent release of free fatty acids, diacylglycerols, monoglycerols and glycerol. Besides this, lipases are also efficient in various reactions such as esterification, transesterification and aminolysis [23]. Lipases have received increased attention recently, as evidenced by the increasing amount of information about lipases in the current literature. Also, many microbial lipases are available as commercial products, the majority of which are used in detergents, paper production, cosmetic production, food flavoring, organic synthesis and some other industrial applications [24–26]. The enzyme detergent market share has currently reached 90% in Europe, and in Japan around 80%. Lipases are valuable biocatalysts, because they act under mild conditions and are highly stable in organic solvents, show broad substrate specificity[27–29].

With the exploitation of marine resources, the pelagic fishes have become the primary target of fishery: these species are resourceful and potential. However, the fat content is high in these species; people have to face the certain difficulties for fish preservation, processing, marketing. Currently, the traditional methods for fish degreasing include expression method, extraction method and alkaline processing, while compared with these traditional methods, using lipases has incomparable advantages. Therefore, applications of lipases in the fish processing field are causing growing concern[30,31].

Microbial lipase was first found from Penicillium Oxalicum and Aspergillus flavus in 1935 by Kirsh [32]. Feller et al. (1990) screened four cold-adapted lipases secreted by Moraxella. These Moraxella were obtained from the Antarctic seawater with the optimum growth temperature of 25 ºC, and the maximum secretion of lipases was supposed to occur at lower temperature conditions, the lowest secretion temperature can reach 3 ºC [33]. Wang et al. screened out nine lipase producing strains from a total of 427 yeast strains. They belonged to Candida intermedia YA01a, Pichia guilliermondii N12c, Candida parapsilosis 3eA2, Lodderomyces elongisporus YF12c, Candida quercitrusa JHSb, Candia rugosa wl8, Yarrowia lipolytica N9a, Rhodotorula mucilaginosa L10-2 and Aureobasidium pullulans HN2.3. Some lipases could actively hydrolyze different oils, indicating that they may have potential applications in industry [34]. In 2009, a novel extracellular phospholipase C was purified from a marine streptomycete, which was selected from approximately 400 marine bacteria by Mo et al. Its enzyme activity was optimal at pH 8.0 at 45 ºC, and it hydrolyzed only phosphatidylcholine[35].

The marine environment is extremely complex, including low-temperature, high-temperature, high hydrostatic pressure, strong acid, strong alkali, and very poor nutritional conditions. An extremophilic microorganism is a microorganism that thrives in, and may even require, physically or geochemically extreme conditions that are detrimental to the majority of life on Earth. Extremophilic microorganisms are adapted to survive in ecological niches, they must adaptively change their physiological structure and metabolism, in order to adapt to the extreme environmental conditions. (Table 1) Therefore, extremophilic microorganisms screened from these environments, may have some specific physiological principles, which can produce unique biocatalysts that function under extreme conditions comparable to those prevailing in various industrial enzymes. Because of this reason, in recent years, research programs investigating extremophilic microorganisms became a new area of interest in microbial research and are very popular[91–94].

Algoriphagus, psychrotrophs and other low-temperature microorganisms have obvious advantages in the ecology. The low-temperature microorganisms cannot readily be involved in contamination. Their culture condition is simple, and the enzymes from these microorganisms have advantages of high activity and high catalytic efficiency. Hence, with the assistance of low-temperature microbial enzymes, it can greatly shorten the processing time and save expensive heating/cooling systems, thus save considerable energy. Cold-adapted enzymes from marine microorganisms, especially, the lipases and proteases, have considerable potential, particularly in the cleaning industry. Many studies have shown that about 77% of Antarctic marine bacteria are resistant to cold environments and 23% are addicted to a cold environment. The unique geography and climate characteristics in Antarctica forms a dry, bitterly cold, strong radiation environment, in which microorganisms have to survive with corresponding unique molecular mechanism, physiological and biochemical characteristics. For these reasons, the Antarctic marine bacteria are thought to produce new bioactive substances with significant potential [95]. In 1994, Feller screened α-amylase-generating bacteria Alteromonas haloplanktis from the Antarctic, which can grow well at 4 ºC, however cell proliferation and enzyme secretion is suppressed at 18 ºC; mean while, at 0 ~30 ºC the activity of this α-amylase is seven-times higher than α-amylases from homeothermic animals [96]. Kolenc transferred TOL plasmid pWWO of mesophilie Psychrotrophs putida PaW1 to the psychrotroph Psychrotrophs putida Q5. From expression of the genes, it was shown that the transconjugant had the capacity to degrade and utilize toluate (1,000 mg/liter) as a sole source of carbon at temperatures as low as 0 °C [97]. Transferring the useful gene from mesophilic microorganisms to psychrophilic ones was established to promote low-temperature microbial biological features, which may have enormous potential in removing pollution in cold environments.

Near the deep sea volcanoes, some microorganisms can survive in extreme conditions, even over temperatures of 100 ºC. Therefore, these microorganisms are supposed to have unique enzyme systems, which can work in these high temperature conditions. For example, the nucleic acid enzymes, such as DNA polymerase, ligase and restriction endonuclease, have a significant applicational value in molecular biology research. Iundberg’s group purified a thermostable DNA polymerase from thermophilic archaea (Pyrococcus furiosus), which has polymerizing and proofreading double functions, and has high activity even at 100 ºC. Hence, this polymerase can be applied in high fidelity PCR experiments [98,99]. In 2008 a novel thermostable non-specific nuclease from thermophilic bacteriophage GBSV1 was isolated by Song’s group, this non-specific nuclease can degrade various nucleic acids, including RNA, single-stranded DNA and double-stranded DNA[100].

Studies have shown hydrostatic pressure can obviously promote enzyme thermal stability. Generally, enzymes have a good three-dimensional specificity under hydrostatic pressure, but when pressure exceeds a certain range, the enzyme’s weak bond can be easily destroyed, thereby leading to the disintegration of the enzyme conformation. The deep-sea is regarded as an extreme environment with conditions of high hydrostatic pressure, Enzymes from deep-sea microorganisms are thought to have characteristic pressure-adaptation mechanisms in structure and function, and they can be utilized in high hydrostatic pressure environments without disintegration. Microorganisms obtained from deep-sea environments appear to be an important source of modern enzyme industries. In 1979, the first barophilic bacteria was isolated from a deep-sea sample and has been found to grow optimally at about 500 bars and 2–4 ºC. Japanese scientists isolated multiple strains of bacteria addicted to pressure from the marine environment, and found that the in vivo genes, proteins and enzymes in the deep-sea still have a high ability. The discovery and research of the marine barophilic microorganisms provide a good foundation for further development on extreme enzymes[92,93].

There are some regions in oceans, where microorganisms from these locales are commonly highly acidophilic or alkalophilic: they can live in conditions of pH 5, even below pH 1, or alternatively over pH 9 conditions. Extracellular enzymes secreted by these microorganisms are commonly acidophilic enzymes (optimum pH < 3.0) or alkalophilic enzymes (optimum pH > 9.0). Compared with the neutral enzymes, the extreme pH enzymes show good stability in the environment, due to the particular enzyme molecule containinghigh proportion of acidic or basic amino acids. The enzymes, produced by acidophilic or alkalophilic microorganisms, could have wide applications for compound synthesis in extreme pH conditions [101–103]. In the ocean, the average seawater salinity is about 3.5%, but in some regions it could be higher. A large number of salt-tolerant or halophilic microorganisms will survive in these high salinity areas, and enzymes from halophilic microorganisms can maintain the stability at high salt concentrations [94,103].

The 21st century is the century of the ocean, and the ocean is a vast treasure of human life. Recently, most countries face similar problems such as high population, resource consumption and pollution. Meanwhile, the marine biological progress and development gives a new source and options to humans. Marine microbial enzymes, especially marine extreme microbial enzymes, have become more and more important in applications.

Because enzymes have unequalled advantages, many industries are keenly interested in adapting enzymatic methods to the requirements of their processes. Clinical application of enzymes has been developing also. For example, surgeons used proteolytic enzymes for debridement of wounds, and promising clinical results have been reported by injection of certain enzymes such as streptokinase, crystallinetrypsin, and chymotrypsin. Since the increased therapeutic use of enzymes, presently unpredictable, rapid advances in this field may be expected[104].

Uses of enzymes have increased greatly during the past few years. Prospects are excellent for continuing to increase the usage of presently available enzymes in present applications, and in new uses, and also in the use of new enzymes for many purposes. also In addition, some new fields, like metagenomics, offer a powerful lens for viewing the microbial world that may have the potential to revolutionize our understanding of the marine microbial enzymes. Japan constantly increases its support to marine microbial enzymes research, and from 1992, the Japanese government made a series of marine microorganisms, planned to discover and clone proteins or enzymes with some special activity. In addition, Canada, Spain, Finland and Russia and other countries have also stepped up on marine bio-enzyme research.

Collectively, due to marine biological diversity and the specificity of biological metabolism, the study on a global scale is still just beginning, but it has huge potential for development and applications with industrial benefits.