Cheese, a culinary delight enjoyed worldwide, owes its diverse and distinct characteristics to a complex interplay of microorganisms, particularly the lactic acid bacteria (LAB), that define its microbial ecology. Local cheeses, rooted in traditional practices, showcase a unique blend of flavors, textures, and aromas influenced by the intricate relationships between microorganisms, environmental factors, and cheese-making techniques. Understanding the microbial ecology of local cheese is not only key to preserving time-honored artisanal methods but also crucial for unlocking the potential for innovation in cheese production (Bianca et al., 2023; Beata et al., 2022; Magnólia et al., 2023). This article explores the multifaceted world of the microbial communities in local cheese, with a special focus on the role of lactic acid bacteria. LAB, as the predominant group in cheese ecosystems, contributes significantly to acidification, flavor development, and safety. The microbial diversity in cheese, shaped by indigenous microflora, starter cultures, and ripening agents, results in rich sensory profiles that characterize various local cheese varieties (Muhammed et al., 2022; Silvano, Focardi, 2022). As we delve into the microbial ecology of local cheese, we uncover the influences of geographical locations, animal husbandry practices, and traditional techniques on microbial composition. The journey extends beyond the primary cheese-making process, encompassing the ripening and aging stages, where dynamic microbial communities continue to mold the biochemical and sensory characteristics of the final product. (Benjamin et al., 2013) Cheese is a model for studying microbes in complex communities.

High-throughput sequencing and computational frameworks help understand ecosystem processes. The paper discusses the use of cheese as a model for studying microbial communities.

It proposes the application of an ecosystems biology approach to understand cheese microbiology

Through this exploration, we aim to unravel the intricate world of microorganisms that coalesce to create the flavorsome and culturally significant local cheeses. The knowledge gained not only serves to preserve traditional cheese-making practices but also opens avenues for innovation, ensuring product consistency, and elevating the art of cheese production to new heights. Join us on this journey into the microbial ecology of local cheese, where science meets tradition to craft the myriad delights found in every wheel and wedge. Lactic acid bacteria (LAB) play a crucial role in the microbial ecology of local cheeses. The diversity of LAB species and strains in different types of cheeses has been investigated (Matthew et al., 2023; Beata et al., 2022, Fabrizio et al., 2023; Magnólia et al., 2023). These studies have focused on identifying and characterizing LAB isolates from various cheese samples, including Pecorino Siciliano PDO, ripened and unripened cheeses, and Feta and Kefalograviera cheeses. The analysis of LAB populations has been done using metagenomic and microbiological approaches, as well as genotyping tools and whole-genome sequencing (Markella et al., 2022). The presence of antibiotic resistance genes (ARGs) in LAB isolates from cheese samples has also been investigated, highlighting the potential threat posed by the widespread presence of ARGs in LAB present in regional cheeses. Overall, these studies provide valuable insights into the microbial ecology of local cheeses, with a specific focus on LAB (Jakaria Al-Mujahidy et al., 2024).

Related Work

The microbial ecology of local cheese has been studied in several papers. Nalepa and Markiewicz investigated the microbial diversity of ripened and unripened cheeses produced from cow, ewe, and goat milk in Poland. They identified lactic acid bacteria (LAB) typical for cheeses and microbiota characteristic of the investigated types of cheese. They also assessed the phenotypic antibiotic resistance (AR) and the presence of antibiotic resistance genes (ARG) in LAB (Beata et al., 2022) Murray et al. evaluated the microbial ecology of Pecorino Siciliano PDO cheese using metagenomic and microbiological approaches. They found farm-specific dairy lactococcal and streptococcal isolates with diverse genotypic features, including newly described phage-resistance systems( Matthew et al., 2023)  Ekici et al. measured the microbial counts and biogenic amine concentrations in herby cheese. They found a range of bacterial and fungal loads in the cheese samples and detected various biogenic amines, but concluded that the cheeses were fit for consumption. The bacterial load of herby cheese ranged between 4.0 and 8.90 log CFU/g for total aerobic mesophilic bacteria (TAMB) and The detection levels of biogenic amines in the samples ranged from <0.025 to 1438.22 mg/kg (Kamil et al., 2019) Senbetu assessed the microbial quality and hazards of cheese in local markets in Hawassa. They found high microbial loads, including pathogenic bacteria, in the cheese samples, indicating poor sanitary practices (Demeke et al., 2014) Saliu et al. studied the physicochemical and microbial quality of wara cheese in Nigeria. They found that boiling and salting were effective in preserving the cheese and inhibiting spoilage and pathogenic microorganisms (Bolanle et al., 2014).

Microbial Ecology of Local Cheese

Understanding the microbial ecology of local cheese involves exploring the intricate interactions between microorganisms, environmental factors, and cheese-making practices that collectively shape the characteristics of different cheese varieties. The microbial communities present in local cheeses significantly influence their flavor, texture, and overall quality. This section will delve into the microbial ecology of local cheese, emphasizing the diverse microbial populations and their roles in cheese production. Research has shown that the microbial composition of local cheeses is influenced by various factors, including geographical location, animal husbandry practices, and traditional cheese-making techniques. The microbial diversity in cheese is a result of the complex interactions between indigenous microflora, starter cultures, and ripening agents, all of which contribute to the unique sensory profiles of different cheese varieties.

Furthermore, the microbial ecology of local cheese extends beyond the primary cheese-making process to include the ripening and aging stages, where dynamic microbial communities continue to shape the biochemical and sensory characteristics of the final product. Understanding the microbial ecology of local cheese is essential for preserving traditional cheese-making practices, ensuring product consistency, and exploring the potential for innovation in cheese production (Wolfe BE, Dutton, 2015; Quigley et al., 2012; Uddin et al., 2022; Montel et al., 2014).

Understanding Lactic Acid Bacteria (LAB)

Lactic acid bacteria (LAB) are a group of Gram-positive, low-GC, acid-tolerant, generally non-sporulating, non-respiring rod or cocci that produce lactic acid as the major metabolic end product of carbohydrate fermentation. They are a diverse group of bacteria, encompassing several genera such as Lactobacillus, Lactococcus, Streptococcus, and Pediococcus, among others. LAB are known for their significant contributions to the food industry, particularly in the fermentation of dairy products, vegetables, meats, and beverages. The metabolic processes of LAB are central to their role in food fermentation. They possess the ability to convert sugars into lactic acid through the process of homofermentative or heterofermentative metabolism, depending on the specific species and environmental conditions. This metabolic activity not only contributes to the preservation of food through acidification but also influences the sensory attributes and nutritional quality of the final products. In the context of cheese production, LAB play a pivotal role in the acidification of milk, which is a fundamental step in the coagulation and curd formation processes. Additionally, LAB contribute to the development of desirable flavors and textures in cheese through the production of various compounds, including volatile organic compounds, diacetyl, and exopolysaccharides (Settanni, Moschetti, 2010; Leroy, De Vuyst, 2004; Hugenholtz, 2013).

Diversity of Lactic Acid Bacteria in Local Cheese

The diversity of lactic acid bacteria (LAB) in local cheese is influenced by various factors such as geographical location, milk sources, animal husbandry practices, and traditional cheese-making techniques (Bianca et al., 2023, Luca et al., 2023). Advanced molecular techniques have been used to assess the microbial diversity and dynamics within cheese ecosystems, revealing a wide range of LAB species and strains in different types of local cheeses) Magnólia  et al., 2023). LAB plays functional roles in cheese fermentation, acidification, proteolysis, lipolysis, and the development of flavor and aroma compounds [31]. The metabolic activities of diverse LAB contribute to the sensory attributes, texture, and overall quality of local cheeses. Indigenous microbial communities also contribute to the sensory attributes and quality of local cheeses. Environmental factors, such as ripening conditions, temperature, and humidity, shape the diversity and stability of LAB populations throughout the cheese-making process. Several key factors can influence LAB in cheese, including (Gobbetti et al., 2002; Quigley et al., 2012; Montel MC et al., 2014).

Role of Lactic Acid Bacteria in Cheese Making

The role of lactic acid bacteria (LAB) in cheese making is multifaceted and essential to the transformation of milk into cheese. LAB are pivotal in the acidification process, which is a fundamental step in coagulating milk and forming the curd. Additionally, LAB contributes to the development of desirable flavors, textures, and aromas in cheese through their metabolic activities. Numerous studies have elucidated the specific functions of LAB in cheese making, highlighting their ability to ferment lactose and other sugars present in milk, leading to the production of lactic acid. This acidification process lowers the pH of the milk, which is crucial for the coagulation of milk proteins and the formation of the cheese curd. The acidification also helps to inhibit the growth of undesirable microorganisms, contributing to the preservation and safety of the cheese. Furthermore, LAB play a significant role in the breakdown of proteins and lipids, contributing to the development of complex flavor compounds and the characteristic texture of cheese. The metabolic byproducts of LAB, such as diacetyl, acetoin, and various volatile organic compounds, contribute to the diverse and appealing flavor profiles of different cheese varieties. In addition to their primary role in acidification and flavor development, LAB also contributes to the ripening and maturation of cheese. During the ripening process, LAB continues to metabolize lactose and other nutrients, leading to further changes in the texture, flavor, and aroma of the cheese. (McSweeney PLH, Sousa MJ, 2000; Fox PF et al., 2017; Quigley et al., 2013).

Factors Affecting Lactic Acid Bacteria in Cheese

Factors affecting lactic acid bacteria in cheese include salt tolerance, acidifying activity, proteolytic activity, and the ability to produce exopolysaccharides (EPS) and diacetyl (Fabrizio et al., 2023). Temperature, pH, salt concentration, and the presence of glucose and lactose also influence the growth and biofilm formation of lactic acid bacteria in cheese (Mirjana et al., 2018). The type of media used, such as whole milk, skim milk, cheese whey, or non-fat milk, can affect the growth and lactic acid production patterns of lactic acid bacteria. (Oluwadamilare et al., 2019) Environmental conditions, such as temperature, pH, salt concentration, and glucose and lactose concentrations, can impact the planktonic growth and biofilm formation ability of lactic acid bacteria. (Aylin, Akoğlu, 2020) Nonstarter lactic acid bacteria (NSLAB), including lactobacilli, can have a positive, neutral, or negative effect on cheese flavor development, and controlling the composition and growth of NSLAB communities is important for consistent cheese quality (Islam et al., 2020; Diyora, Abdurah-monova., 2022).

Milk Quality 

The quality of the milk used in cheese production significantly impacts the microbial composition, as well as the growth and activity of LAB. Factors such as the initial microbial load, milk composition, and the presence of inhibitory substances can influence the development of LAB populations.

Environmental Conditions 

The environmental factors within the cheese-making facility, including temperature, humidity, and air quality, can affect the growth and behavior of LAB. Proper environmental control is essential for maintaining the desired microbial ecology during cheese production.

Cheese-Making Practices 

The specific techniques and methods employed during cheese making, such as the use of starter cultures, coagulation conditions, curd handling, and salting, can influence the abundance and diversity of LAB in cheese.

Ripening Conditions 

The conditions during cheese ripening, including temperature, humidity, and oxygen availability, can impact the metabolic activities of LAB and other microorganisms, leading to changes in the flavor, texture, and overall quality of the cheese.

Microbial Interactions 

The interactions between LAB and other micro-organisms present in the cheese, including non-starter lactic acid bacteria, yeasts, and molds, can influence the overall microbial ecology and the development of cheese characteristics.

Importance of Microbial Ecology in Cheese Quality

The importance of microbial ecology in cheese quality is a critical aspect of cheese production, as the complex interactions between microorganisms significantly influence the sensory attributes, safety, and shelf-life of cheese. The microbial ecology of cheese encompasses the diverse populations of lactic acid bacteria, non-starter lactic acid bacteria, yeasts, molds, and other microorganisms that contribute to the ripening and maturation processes. Research has demonstrated that the microbial composition and dynamics within cheese ecosystems play a fundamental role in shaping the flavor, texture, and aroma of cheese. The metabolic activities of lactic acid bacteria and other microorganisms contribute to the development of desirable flavor compounds, the breakdown of proteins and lipids, and the production of volatile organic compounds, all of which are essential for the sensory characteristics of cheese. Furthermore, the microbial ecology of cheese is closely linked to safety and preservation. The acidification and competitive exclusion mechanisms mediated by lactic acid bacteria inhibit the growth of pathogenic and spoilage microorganisms, contributing to the safety and extended shelf-life of cheese.

Microbial Components in Cheese

Cheese production involves various microbial components that play a crucial role in the quality, typicality, and safety of the final product. Microorganisms, such as lactic acid bacteria (LAB), are the majority components of the cheese microbiota and are involved in the fermentation and ripening processes. These microorganisms contribute to the transformation of milk, confer typicity and stability to cheese, and produce antimicrobial compounds that prevent spoilage (Silvano, Focardi, 2022). Other micro-organisms, including starter bacteria, nonstarter lactic acid bacteria, enterococci, micrococci, staphylococci, coryneform, propionic acid bacteria, yeasts, and molds, also play important roles in cheese production. (Mary, Skopec, 2022). The microbiological characteristics of different cheese groups, such as white-brined, hard, blue, surface-ripened, Swiss, Dutch, and pasta-filata types, are influenced by these microorganisms (Baltasar et al., 2021). Understanding the dynamics and interactions between different microbial types in the cheese microbiota is essential for predicting fermentation success and developing functional starters. (Gustavo et al., 2022) Additionally, controlling microbial growth through factors like water activity, salt, pH, and temperature is crucial for ensuring the safety and quality of cheese. 

Impact on Cheese Characteristics (Wolfe BE et al., 2014; Coelho et al., 2022; Nicosia et al., 2023)

Flavor, Texture, and Aroma

Lactic Acid Bacteria (LAB): Produce lactic acid, contributing to acidity and tanginess. Contribute to the formation of various flavor compounds.

Yeasts and Molds: Release enzymes that break down proteins and lipids, influencing texture and contributing to the development of complex flavors.

Safety and Preservation

LAB Acidification 

Creates an acidic environment that inhibits the growth of pathogenic microorganisms, contributing to the safety of cheese.

Competitive Exclusion 

LAB outcompete undesirable microbes for nutrients, further enhancing safety.

Research Findings

Flavor Development

A study (cite source) found that the presence of specific LAB strains correlated with the production of compounds contributing to the fruity and nutty flavors in certain cheese varieties.

Safety Mechanisms

Research (cite source) demonstrated the inhibitory effect of LAB-produced bacteriocins on pathogenic bacteria, enhancing the safety of cheese.

Shelf-Life Extension

Cheese with well-established LAB populations tend to have a longer shelf life due to the inhibitory effects against spoilage microorganisms.

In conclusion, the microbial ecology of local cheese, with a particular emphasis on lactic acid bacteria (LAB), is integral to the intricate processes of cheese production. LAB, as the predominant group, significantly influences acidity, flavor development, and safety, establishing them as key players in shaping the unique characteristics of local cheeses. The collaborative efforts of LAB, yeasts, and molds contribute to the complex flavor profiles and textures that define various cheese varieties. Research findings underscore the practical implications of these microbial interactions, revealing correlations between specific LAB strains and distinct flavors, and demonstrating the inhibitory effects of LAB-produced bacteriocins on pathogenic bacteria, ensuring the safety of cheese. Furthermore, the extended shelf life observed in cheeses with well-established LAB populations emphasizes the economic and quality benefits of understanding and harnessing microbial dynamics. This exploration into the microbial ecology of local cheese highlights its multifaceted nature, encompassing flavor development, safety mechanisms, and preservation. As we unravel the complexities of these microbial interactions, it becomes evident that a comprehensive understanding is not only essential for preserving traditional cheese-making practices but also for fostering innovation in cheese production. In essence, the microbial ecology of local cheese is a cornerstone in the quest for consistent quality, safety, and the preservation of time-honored traditions in the art of cheese making.

We are grateful to all the dear professors for providing their information regarding this research.

The author declared obviously in the manuscript and has no conflict of interest.