Microbial Enzymes and Their Applications in Food Industry: A Mini-Review

The use of enzymes is replacing chemicals in many industrial production processes because of the eco-friendly nature of enzymes which do not generate greenhouse gases and have reduced the demand for energy in industries. To meet the ever-increasing demand for enzymes in many industries and survive the harsh production conditions, microbial sources of enzyme production are the most preferred source for industrial enzyme production because the microbes are readily available, they grow at a very fast rate, and they can be genetically manipulated to produce enzymes which can perform optimally at different industrial production conditions. Microbial enzymes have found so many applications in various industries (textiles, leather, paper and pulp, research and development, pharmaceutical, agriculture, detergent, waste, biorefineries, photography and food industries), thus making them very essential in several industrial production processes. Here in this review, the application of some important microbial enzymes in food industry and the microbial sources for the enzymes are discussed.

Mechanisms by which microbial enzymes degrade four mycotoxins and application in animal production:A review

Mycotoxins are toxic compounds that pose a serious threat to animal health and food safety.Therefore,there is an urgent need for safe and efficient methods of detoxifying mycotoxins.As biotechnology has continued to develop,methods involving biological enzymes have shown great promise.Biological enzymatic methods,which can fundamentally destroy the structures of mycotoxins and produce degradation products whose toxicity is greatly reduced,are generally more specific,efficient,and environmentally friendly.Mycotoxin-degrading enzymes can thus facilitate the safe and effective detoxification of mycotoxins which gives them a huge advantage over other methods.This article summarizes the newly discovered degrading enzymes that can degrade four common mycotoxins(aflatoxins,zearalenone,deoxynivalenol,and ochratoxin A)in the past five years,and reveals the degradation mechanism of degrading enzymes on four mycotoxins,as well as their positive effects on animal production.This review will provide a theoretical basis for the safe treatment of mycotoxins by using biological enzyme technology.

Effects of butachlor on microbial enzyme activities in paddy soil

This paper reports the influences of the herbicide butachlor( n butoxymethl chloro 2', 6' diethylacetnilide) on microbial respiration, nitrogen fixation and nitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that after application of butachlor with concentrations of 5.5 μg/g dried soil, 11.0 μg/g dried soil and 22.0 μg/g dried soil, the application of butachlor enhanced the activity of dehydrogenase at increasing concentrations. The soil dehydrogenase showed the highest activity on the 16th day after application of 22.0 μg/g dried soil of butachlor. The hydrogen peroxidase could be stimulated by butachlor. The soil respiration was depressed within a period from several days to more than 20 days, depending on concentrations of butachlor applied. Both the nitrogen fixation and nitrification were stimulated in the beginning but reduced greatly afterwards in paddy soil.

Effects of different forms of nitrogen addition on microbial extracellular enzyme activity in temperate grassland soil

Background:Nitrogen(N)deposition alters litter decomposition and soil carbon(C)sequestration by influencing the microbial community and its enzyme activity.Natural atmospheric N deposition comprises of inorganic N(IN)and organic N(ON)compounds.However,most studies have focused on IN and its effect on soil C cycling,whereas the effect of ON on microbial enzyme activity is poorly understood.Here we studied the effects of different forms of externally supplied N on soil enzyme activities related to decomposition in a temperate steppe.Ammonium nitrate was chosen as IN source,whereas urea and glycine were chosen as ON sources.Different ratios of IN to ON(Control,10:0,7:3,5:5,3:7,and 0:10)were mixed with equal total amounts of N and then used to fertilize the grassland soils for 6 years.Results:Our results show that IN deposition inhibited lignin-degrading enzyme activity,such as phenol oxidase(POX)and peroxidase(PER),which may restrain decomposition and thus induce accumulation of recalcitrant organic C in grassland soils.By contrast,deposition of ON and mixed ON and IN enhanced most of the C-degrading enzyme activities,which may promote the organic matter decomposition in grassland soils.In addition,theβ-N-acetyl-glucosaminidase(NAG)activity was remarkably stimulated by fertilization with both IN and ON,maybe because of the elevated N availability and the lack of N limitation after long-term N fertilization at the grassland site.Meanwhile,differences in soil pH,soil dissolved organic carbon(DOC),and microbial biomass partially explained the differential effects on soil enzyme activity under different forms of N treatments.Conclusions:Our results emphasize the importance of organic N deposition in controlling soil processes,which are regulated by microbial enzyme activities,and may consequently change the ecological effect of N deposition.Thus,more ON deposition may promote the decomposition of soil organic matter thus converting C sequestration in grassland soils into a C source.

Shifts in microbial community structure and diversity in a MBR combined with worm reactors treating synthetic wastewater

The chemical oxygen demand（COD） and NH3-N removal, membrane fouling, sludge characteristics and microbial community structure in a membrane bioreactor（MBR） coupled with worm reactors（SSBWR） were evaluated for 210 days. The obtained results were compared to those from a conventional MBR（C-MBR） operated in parallel. The results indicated that the combined MBR（S-MBR） achieved higher COD and NH3-N removal efficiency,slower increase in membrane fouling, better sludge settleability and higher activities of the related enzymes in the activated sludge. Denaturing gradient gel electrophoresis was used to analyze the microbial community structures in the C-MBR and the S-MBR. The microbial community structure in the S-MBR was more diverse than that in the C-MBR. Additionally, the slow-growing microbes such as Saprospiraceae, Actinomyces, Frankia, Clostridium, Comamonas,Pseudomonas, Dechloromonas and Flavobacterium were enriched in the S-MBR, further accounting for the sludge reduction, membrane fouling alleviation and wastewater treatment.