TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Fusion Protein: The membrane-active peptide comprises an antimicrobial peptide. The membrane-active peptide is magainin 2, protegrin, protegrin-1, melittin, 11-37, dermaseptin, cecropin, caerin, ovispirin, alamethicin, or their homologs, or variants. The second polypeptide comprises maltose binding protein, green fluorescence protein (GFP), chloramphenicol acetyltransferase (CAT), thioredoxin (Trx), or their homologs, or fragment. The membrane-active peptide comprises 10-200 amino acid residues, preferably 15-50 amino acid residues. The second peptide increases solubility of the fusion membrane in the cell expressing the fusion protein, where the fusion protein forms a pore in the membrane, and where the membrane-active peptide forms an alpha-helical structure or a beta-pleated sheet structure in a membrane that increases membrane permeability. The fusion protein increases cellular membrane permeability to an extracellular reactant. The fusion protein increases cellular membrane permeability to an intracellular component or polypeptide.Preferred Vector: The vector further comprises an inducible promoter. The vector comprises a plasmid.Preferred Composition: The composition further comprises a physiologically buffered carrier solution.Preferred Cell: The cell is selected from prokaryotic or eukaryotic cells. The cell is mammalian, bacterial, fungal, or plant. The membrane-active peptide comprises a net positive charge. The membrane-active peptide or their fusion proteins, form a porous multimeric complex in the cell membrane. The membrane-active peptide or its fusion protein, forms a pore in the cell membrane. The membrane-active peptide or its fusion protein, increases membrane permeability to an extracellular reactant. The membrane-active peptide or its fusion protein, increases membrane permeability to an intracellular enzymatic reaction product. The membrane-active peptide or its fusion protein, increases membrane permeability to a protein produced by the cell. The protein produced by the cell is a natural or recombinant protein.Preferred Method: Increasing the recovery of a recombinant polypeptide from a cell comprises expressing in the cell a nucleic acid encoding membrane-active peptide or its fusion protein, where the membrane-active peptide or its fusion protein, increases membrane permeability of the cell and allows the recombinant protein produced by the cell to translocate one or more cellular membranes thus increasing recovery of the recombinant polypeptide compared to a control cell. Increasing the yield of an enzymatic product from a cell comprises expressing in the cell a nucleic acid encoding a membrane-active peptide or its fusion protein, where the membrane-active peptide or its fusion protein, increases membrane permeability of the cell allowing extracellular reactants to translocate cellular membranes of the cell at a higher rate and thus the conversion rate of the reactants to products is much higher compared to a control cell. Bioremediation comprises contacting a cell comprising an enzyme capable of converting a toxic reactant into a non-toxic product with the membrane-active peptide or its fusion protein, and contacting the cell with the toxic reactant under conditions that favor the conversion of the toxic reactant into a non-toxic product, where the toxic reactant is converted into the non-toxic product. Controlling membrane permeability of a cell, comprises expressing one or more vectors in the cell, where membrane permeability increases with an increase in number of vectors in the cell, an increase in amount of inducer in contact with the cell, or an increase in strength of the promoter of the one or more vectors or other genetic elements within the vector.Preferred Cellular Array: The detectable phenotypic change is a change in color, shape, number of cells, apoptosis, or production or a detectable label. EXAMPLE - A codon-optimized gene corresponding to the pore-forming peptide Mag II was synthesized along with two restriction sites BamHI and SalI, and cloned into a cytoplasmic expression vector, c2x, as a fusion to the maltose binding protein (MaIE). The fusion strategy was chosen as short peptides are particularly susceptible to proteases. The expression was under the control of the Tac promoter, inducible with isopropyl-beta-D-thiogalactopyranoside (IPTG). One clone, referred as cM13, was one of many clones obtained that had the correct sequence and was in frame with MalE, and was chosen for further study. The successful expression of MagII in Escherichia coli was evident from the sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The fusion protein appeared as a strong band with the correct size. The expression apparently was dependent on the inducer concentration and increased with time. However, there was only a limited increase in expression at IPTG concentrations greater than 0.3 mM, and at time points beyond four hours after the induction. The Western blot analysis using an antibody against MalE showed two bands in all induced samples but not in uninduced ones, a strong band corresponding to the molecular size of the MalE-MagII fusion and a weak band corresponding to MalE, suggesting that a small fraction of the fusion was degraded. But a majority of the fusion was intact and the degraded fraction did not seem to significantly increase with the time and with the inducer concentration.