Abstract: Disclosed embodiments concern concentrated compositions comprising a microbial suspension and a preservative system, such as a paraben preservative, an isothiazolinone preservative, and a quaternary ammonium preservative. Microbes used to form the compositions generally are spore-forming microbes, such as bacteria or fungi, with representative embodiments concerning compositions comprising Bacillus. Concentrated compositions may be formulated by combining a Prep A composition comprising a microbial suspension with a Prep B composition comprising a preservative system. Preserved concentrated microbial compositions may be formulated at any of various concentrations relative to diluted, ready-to-use compositions, such as 40×, 50×, 80×, 100× and 250× compositions. Diluted microbial suspension compositions can be used as a cleaning product, an odor control aid, as a janitorial product, as an agricultural product, as a product to treat wastewater, as an environmental product, or as a processing aid.