Statistical Design, a Powerful Tool for Optimizing Biosurfactant Production: A Review <s> Modified Gompertz Equation <s> The Gompertz model is well known and widely used in many aspects of biology. It has been frequently used to describe the growth of animals and plants, as well as the number or volume of bacteria and cancer cells. Numerous parametrisations and re-parametrisations of varying usefulness are found in the literature, whereof the Gompertz-Laird is one of the more commonly used. Here, we review, present, and discuss the many re-parametrisations and some parameterisations of the Gompertz model, which we divide into Ti (type I)- and W0 (type II)-forms. In the W0-form a starting-point parameter, meaning birth or hatching value (W0), replaces the inflection-time parameter (Ti). We also propose new "unified" versions (U-versions) of both the traditional Ti -form and a simplified W0-form. In these, the growth-rate constant represents the relative growth rate instead of merely an unspecified growth coefficient. We also present U-versions where the growth-rate parameters return absolute growth rate (instead of relative). The new U-Gompertz models are special cases of the Unified-Richards (U-Richards) model and thus belong to the Richards family of U-models. As U-models, they have a set of parameters, which are comparable across models in the family, without conversion equations. The improvements are simple, and may seem trivial, but are of great importance to those who study organismal growth, as the two new U-Gompertz forms give easy and fast access to all shape parameters needed for describing most types of growth following the shape of the Gompertz model. <s> BIB001 </s> Statistical Design, a Powerful Tool for Optimizing Biosurfactant Production: A Review <s> Modified Gompertz Equation <s> Background: Surfactant is one of the most important raw materials used in various industrial fields, such as emulsifiers, corrosion inhibitors, foaming agent and detergent products. However, the commercial surfactant production is still costly and its demand is steadily increasing. This study aims to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through a fermentation process. It also included the investigation of effect of initial glucose concentration and the ratio of carbon to nitrogen. Results: The biosurfactant was produced in the range of 1-2.46 g/L at initial glucose concentrations of 10-70 g/L. The optimum condition was achieved at a carbon to nitrogen ratio of 12.4 with the decrease in surface tension up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation was proposed to predict the cell mass and biosurfactant production as the goodness of fitting was obtained. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ ::: table.MsoNormalTable ::: {mso-style-name:"Tabla normal"; ::: mso-tstyle-rowband-size:0; ::: mso-tstyle-colband-size:0; ::: mso-style-noshow:yes; ::: mso-style-priority:99; ::: mso-style-parent:""; ::: mso-padding-alt:0cm 5.4pt 0cm 5.4pt; ::: mso-para-margin:0cm; ::: mso-para-margin-bottom:.0001pt; ::: mso-pagination:widow-orphan; ::: font-size:10.0pt; ::: font-family:"Times New Roman",serif; ::: mso-ansi-language:EN-GB; ::: mso-fareast-language:EN-GB;} <s> BIB002
The Gompertz model is well known and widely used in many aspects of biology. It has been frequently used to describe the growth of animals and plants, as well as the number or volume of bacteria and cancer cells BIB001 . However, an interesting study with a very different and novel approach was carried out by Heryani and Putra BIB002 . For the first time, a modified version of the Gompertz model was used to predict the cell mass and Bs production by Bacillus sp. strains. This model was also demonstrated to precisely predict ST. The results showed that glucose had a negative effect on surfactin production (high concentrations of glucose inhibited Bs production). The optimum C/N ratio was also determined using this method. Maximum Bs production reached 2.46 gL −1 with the lowest ST recorded at 27.05 mNm −1 .