Phenotypic and Genotypic Investigation of Two Representative Strains of Microbacterium Species Isolated From Micro-Filtered Milk: Growth Capacity and Spoilage-Potential Assessment

Abstract

The microbiota that spoil long-life micro-filtered milk generally includes species of the genus Microbacterium. The metabolic properties of this of microorganisms that could potentially modify the quality of micro-filtered milk are still unexplored when compared to better-known microorganisms, such as the spore-forming Bacillus and Paenibacillus spp., and Gram-negative contaminants, such as species of the genera Pseudomonas and Acinetobacter. In this preliminary study, two strains of Microbacterium (M. lacticum 18H and Microbacterium sp. 2C) isolated from micro-filtered milk were characterized in depth, both phenotypically and genotypically, to better understand their role in long-term milk spoilage. The study highlights the ability of these strains to produce high cell numbers and low acidification in micro-filtered milk under storage and shelf-life conditions. Phenotypic analyses of the two Microbacterium sp. isolates revealed that both strains have low proteolytic and lipolytic activity. In addition, they have the ability to form biofilms. This study aims to be a preliminary investigation of milk-adapted strains of the Microbacterium genus, which are able to grow to high cellular levels and perform slight but not negligible acidification that could pose a potential risk to the final quality of microfiltered milk. Furthermore, M. lacticum 18H and Microbacterium sp. 2C were genotypically characterized in relation to the characteristics of interest in the milk environment. Some protein-encoding genes involved in lactose metabolism were found in the genomes, such as β-galactosidase, lactose permease, and L-lactate dehydrogenase. The phenotypically verified proteolytic ability was supported in the genomes by several genes that encode for proteases, peptidases, and peptide transferases.

Microbacterium paulum sp. nov., isolated from microfiltered milk

“…The bacterial strain evaluated in this study (2C T ) is part in a collection of strains belonging to the genus Microbacterium deposited in Università Cattolica del Sacro Cuore under the accession UC4135. Strain 2C T was previously isolated from freshly packaged microfiltered milk on milk plate count agar (Oxoid) supplemented with triphenyl tetrazolium chloride [9]. The working culture of the strain is maintained at 30 and 8 °C in tryptic soy broth (TSB) and skimmed milk.…”

“…The genus was classified into the family Microbacteriaceae , order Microbacteriales , class Actinomycetia , and the type species is Microbacterium lacticum [3]. Microbacterium strains have been isolated from various environments, including air [4], compost [5, 6], faeces [7, 8], food [9], rhizosphere [10–12], seawater [13], sediment [14] and soil [15].…”

Comparative analysis of assembly algorithms to optimize biosynthetic gene cluster identification in novel marine actinomycete genomes

“…The GC-rich nature of actinomycete genomes makes sequencing and assembly very challenging (Benjamini and Speed, 2012;Rajwani et al, 2021). To optimize the success of this genome mining strategy, three assembly pipelines were compared for their particular ability to efficiently assemble reads and minimize gaps in actinomycete genomes.…”

“…To optimize the success of this genome mining strategy, three assembly pipelines were compared for their particular ability to efficiently assemble reads and minimize gaps in actinomycete genomes. Based on successful strategies described in the literature, the following pipelines were evaluated: SPAdes (SPAdes, RRID : SCR_000131) (Bankevich et al, 2012), Shovill (shovill, RRID : SCR_017077) (Seemann, 2020) and A5-miSeq (A5-miseq, RRID : SCR_012148) (Tritt et al, 2012;Coil et al, 2015) (Klein et al, 2016;Koenigsaecker et al, 2016;Schorn et al, 2016;Durrell et al, 2017;Egidi et al, 2017;Kincheloe et al, 2017;Bellassi et al, 2020;Blackwell et al, 2021;Soldatou et al, 2021;Tarlachkov et al, 2021). All three pipelines assemble raw Illumina data with slightly different processing steps.…”

Auxin production and plant growth promotion by Microbacterium albopurpureum sp. nov. from the rhizoplane of leafless Chiloschista parishii Seidenf. orchid

“…a 1, Microbacterium aurantiacum GX14001(Gao et al, 2022); 2, Microbacterium caowuchunii ST-M6 T(Tian et al, 2021); 3, Microbacterium fluvii IDR2; 4, Microbacterium hatanonis JCM14558 T(Bakir et al, 2008); 5, Microbacterium invictum DSM 19600T (Vaz-Moreira et al, 2009); 6, Microbacterium kunmingense JXJ CY 27-2(Xiao et al, 2022) T ; 7, Microbacterium lacticum DSM20427 T(Bellassi et al, 2020); 8, Microbacterium mitrae M4-8 T(Kim et al, 2011); 9, Microbacterium paulum 2C T(Bellassi et al, 2021); 10, Microbacterium saccharophilum K-1 T(Ohta et al, 2013); 11, Microbacterium telephonicum S2T63 T(Rahi et al, 2018); 12, Microbacterium wangchenii dk512 T(Dong et al, 2020). T, type strain of the species.…”